Source: AGRICULTURAL RESEARCH SERVICE - US ARID-LAND RESEARCH CENTER submitted to
SURFACE IRRIGATION WATER QUALITY AND MANAGEMENT
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0404898
Grant No.
(N/A)
Project No.
5347-13000-013-00D
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jan 12, 2002
Project End Date
Jan 11, 2007
Grant Year
(N/A)
Project Director
STRELKOFF T
Recipient Organization
AGRICULTURAL RESEARCH SERVICE - US ARID-LAND RESEARCH CENTER
21881 NORTH CARDON LANE
MARICOPA,AZ 85238
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
60%
Research Effort Categories
Basic
40%
Applied
60%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
4050110200020%
4050210202080%
Goals / Objectives
Guide in design/operation of surface irrigation systems, both traditional and innovative with goals of simulating the transport/fate of water sediments, and nutrients such as phosphorus and nitrogen by irrigation in furrows, border strips, and basins of various types along with attendant field studies; fertigation recommendations; software for presenting overviews of simulalations to aid in the search for an optimum; software to assist in evaluating extant field conditions.Was 5344-13000-010-00D (12/01)
Project Methods
As much as technically feasible, the common thread among the various facets of the project is modeling. The aim is to put design of surface irrigation systems and their operation on a par with other engineering disciplines with reliance on multiple analyses (simulations) with trial values of the design variables in the search for an optimum. Modeling is to be based as far as practicable on basic laws of physics and chemistry with necessary empirical relationships held to a minimum. Essential field studies, inhouse and by cooperating laboratories, are intended to calibrate and validate numerical models of the scenarios of interest. Where the modeling effort is insufficient, timely development of management guidelines will be based primarily on field studies. The performance indicators of good design and management range from effective utilization of available water supplies, to reduction of off-site discharges of sediments, phosphorus, and nitrogen. Formerly 5344-13000-013-00D (2/06).

Progress 01/12/02 to 01/11/07

Outputs
Progress Report 1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? Our research supports National Program 201, Water Quality and Management, falling under Component 2, Irrigation and Drainage Management. It deals with both agricultural water conservation, and the effects of irrigated agriculture on the environment. The National Program problem areas and goals addressed are Problem Area 2.3 (Water Conservation Management), Goal 2.3.3 (Agricultural Water Conservation and Environmental Quality) and also Problem Area 2.6 (Erosion on Irrigated Land), Goal 2.6.2 (Irrigation/Erosion Model). Water supplies are under increasing competition, with urban and environmental water needs often taking precedence over agricultural needs. In the American West, it is becoming clear from tree-ring data that the last 100 years have represented an unusually wet era; the region now appears to be returning to normal, harsh desert conditions. Furthermore, nonpoint-source pollution from irrigated agriculture reduces the quality of groundwater and surface water supplies. Water quality concerns and curtailment of irrigation water rights have already reduced the amount of water available for irrigated agriculture, and it is likely that this trend will continue into the foreseeable future. Because such a large portion of agricultural production comes from irrigated agriculture, the quantity and quality of inexpensive food supplies are threatened by losses of water quantity and quality. At the same time, world population predictions suggest that irrigated agriculture will have to maintain or increase production to satisfy future needs for food and fiber. This research project is helping to develop economically viable and environmentally sustainable irrigation systems through improved water and fertilizer management practices and systems. Surface irrigation is the main focus of this research, because it is an economically viable option for many field crops; it is practiced on more than 50% of the irrigated land in the U.S. and more than 80% worldwide. While surface irrigation efficiencies are often low, they can be significantly improved. With such large quantities of water earmarked for irrigation, even small percentage gains in efficiency can make a big difference. Improved water and nitrogen management techniques, including satisfaction of total maximum daily load (TMDL) requirements, will be central to preventing the projected world food crisis, while maintaining a healthy natural environment. Our research program is aimed ultimately at providing guidelines for surface irrigation management and design, including application of agricultural chemicals in the irrigation water. This program is characterized by a strong computer software component for hydraulic simulation and for analysis of practical management and design problems. The software development is supported by field studies that provide data for calibration and verification of computer models, a real-world test for the simulation theory, and empirical bases for generating system recommendations when computer modeling capabilities alone are insufficient. Specific objectives for the 5-year project duration are: Validated software for: - estimation of field parameters; - design and management aids; - simulation of surface-irrigation hydraulics. Validated surface-irrigation models incorporating fate and transport of sediments, phosphorus, and nitrogen on and off site. Guidelines for water and nutrient management in surface irrigation for minimizing introduction of nitrogen into surface and ground waters, while maintaining soil fertility, crop yields, farm profitability and sustainability. Guidelines for design and management of drain-back and other surface- drained level basins for improved water use. We are collaborating with the Northwest Irrigation and Soils Research Laboratory, ARS, Kimberly, ID, on a joint ARS-CSREES NRI-funded project, Simulation and Validation of Phosphorus Loading in Furrow Irrigation Tailwater. Likewise, we are collaborating with the University of Arizona, Yuma Agricultural Center under the reimbursable agreement, Nitrogen and Phosphorus Transport under Surface Irrigation, partially funded by CSREES/NRI, Development of Guidelines for Fertigation in Surface Irrigation Systems. Through specific cooperative agreements, we are collaborating with Oregon State University on Comparison of Surface Irrigation Measurement- Based Infiltration Parameter Estimation Methods, and with Louisiana State University on Evaluation of Level Basin Irrigation in High Rainfall Zones. 2. List by year the currently approved milestones (indicators of research progress) - Platform languages selected for WinSRFR, our Windows-based integrated surface-irrigation hydraulics software - Sediment transport component of WinSRFR completed Year 2 (FY 2003): - Field evaluation component of WinSRFR completed - Phosphorus fate and transport component of WinSRFR completed - Field studies of nitrogen uniformity and efficiency completed - Field studies of surface drained level basins completed Year 3 (FY 2004): - Furrow-design component of WinSRFR completed - Sediment and phosphorus models validated and calibrated - Preliminary guidelines for fertigation with surface irrigation - Guidelines prepared for drainback level basins Year 4 (FY 2005): - Nitrogen transport in the surface stream modeled. Soil-water chemistry model added - Modeling of surface drained level basins completed Year 5 (FY 2006): - WinSRFR released - Nitrogen-transport model validated and calibrated - Final guidelines on nitrogen fertigation with surface irrigation completed - Guidelines for design and management of surface drained level basins completed Our current project plans only extend through mid FY07. 4a List the single most significant research accomplishment during FY 2006. WinSRFR Integrated surface-irrigation software. Supports National Program 201, Problem Area 2 Irrigation Water Management Researchers at the U.S. Arid Land Agricultural Research Center have released a new comprehensive surface irrigation software product, winSRFR. While action agencies such as the NRCS have long recognized the advantages of using science-based software to develop their recommendations, the complexity and limited scope of existing surface irrigation models and design aids have hampered their broad application. WinSRFR consolidates the DOS-based surface irrigation programs SRFR, BORDER and BASIN, and routines for analyzing surface irrigation evaluation data, into a single Windows-based, user-friendly application. The integrated software has been logically organized to allow users to perform structured surface irrigation analyses, and to provide guidance to the users relative to available analytical options. The program takes advantages of services available to Windows applications, including data exchange with standard office applications such as Word and Excel. Intended users of the software include university researchers and extension agents, farm advisors, irrigation consultants, and most of all, NRCS irrigation specialists, with the last group providing extensive input during the development process aimed at providing solid science at the fingertips of practical action personnel. 4b List other significant research accomplishment(s), if any. Parameter Estimation. Supports National Program 201, Problem Area 2 Irrigation Water Management. Researchers at the U.S. Arid-Land Agricultural Research Center have improved the well known two-point method for estimating infiltration parameters from surface irrigation evaluation data. The two-point method is one of the best known estimation procedures, but the method is not always robust or accurate, and therefore, recommendations on how to improve surface irrigation efficiency will sometimes be incorrect. Engineers at the Arid-Land Agricultural Research Center studied the conditions under which infiltration parameters were poorly estimated and provided revised procedures under these conditions. Incorporated into winSRFR, the improvements should increase the reliability of the estimated infiltration parameters and thus will help action agencies, such as the NRCS, to provide better guidance on surface irrigation improvements. Modeling chemical movement in fertigation. Supports National Program 201, Problem Area 2 Irrigation Water Management Engineers at the Arid-Land Agricultural Research Center have developed mathematical models to predict the transport of chemicals injected into an irrigation stream, including fertilizers. A common fertigation practice under surface irrigation, where fertilizers are applied directly into the irrigation water, can potentially lead to the release of fertilizers to the environment through deep percolation or leaching. A simple model of chemical advection was developed as part of the surface irrigation software program, SRFR. A more complete, but more complicated, model of advection and dispersion of chemicals in the water was developed, in cooperation with the University of Arizona, based on water depths and velocities from SRFR. These models will be used in a comprehensive study of surface irrigation fertigation practices to develop better guidelines for action agencies, like NRCS, so that users can save fertilizer and reduce offsite contamination. 4d Progress report. Supports National Program 201, Problem Area 2 Irrigation Water management Yuma-basin cutoff criteria. In order to test the concept that the time T50 for the irrigation stream to advance to the midpoint of a basin is the key piece of data on which to base an optimum cutoff time, several thousand SRFR simulations were performed, spanning the range of slopes, roughnesses, infiltration characteristics, and inflow rates encountered on the Yuma Mesa. A database of simulations was thus developed, limited to those in which the cutoff time Tco led to just matching the minimum in the post-irrigation infiltration distribution to the required depth of application. A study of the graphed relationships between T50 and Tco should lead to development of a simple tool for irrigators to use to set cutoff and avoid the gross overwatering with excessive deep percolation currently taking place. Surface Irrigation Design. In the past, surface irrigation design procedures used totally different approaches for each surface irrigation method. A new approach has been developed over a number of years that uses the same approach to all methods, but with slightly different assumptions. The approach assumes continuity and force equilibrium in uniform flow, and then uses empirical corrections to approximate the influence of other parameters. The method will soon be published in Sakias ejournal of Land and Water Management. The method allows the development of design contours with any infiltration function, an advantage over current BORDER and BASIN design approaches. The method will serve as the basis for more straightforward, flexible design procedures in winSRFR, where a limited number of simulations will be used to tune the empirical parameters. The methodology that has been worked out for furrows will be applied to borders, basins, and level furrows. Fertigation guidelines. In the research effort to provide guidelines for efficient injection of fertilizer into irrigation water in surface systems, the advection dispersion model developed and calibrated from data gathered from a field experiment conducted at Maricopa, Arizona was applied to three furrow irrigation conditions. The application of the model which was linked to SRFR for estimation of hydraulics was for bromide which is a non-reactive tracer. Rhodamine which is weakly adsorbed onto the soil surface was also applied during the experiment. Instrumentation which allows the analysis of rhodamine is now available to this project and the soil and water samples are currently being analyzed for rhodamine concentration. Use of the reactive tracer, rhodamine, will provide data allowing current chemical transport models linked to SRFR to be extended to incorporate soil interaction with reactive solutes such as phosphate and ammonium. Surface-drained basins. In a project conducted by the Louisiana State University Ag Center in cooperation with Angelina Plantation, Monterey, LA and the U.S. Arid-Land Agricultural Research Center, seven precision-graded fields were chosen for a study to determine the benefits of level basins (zero grade) with surface drainage on the performance of surface irrigation in humid environments. Three sloped and three level fields planted to soybeans and a level field planted to cotton were selected. Flow meters and rain gauges have been installed for all fields to determine water inputs. Water level sensors were also installed on the outlets of three fields to measure surface drainage. Watermark soil water sensors were used to determine soil moisture depletion, and the Arkansas scheduler was used to determine the need for irrigation, in addition to the Watermark sensors. Watermark sensors on the surface were also used to determine water advance. Plans to measure the influence of spin-ditch spacing proved difficult. Results will be analyzed after completion of the season. BMP Project. Researchers at the U.S. Arid Land Agricultural Research Center (ALARC) have entered into an agreement with the State of Arizona Department of Water Resources (ADWR) to conduct an independent evaluation of ADWRs Best Management Practices (BMP) program for agricultural water conservation. ADWR currently has an agricultural water conservation program in place based on a fixed water volume allocation per year, but is expecting the BMP program will provide growers with greater flexibility to respond to changing market conditions while encouraging them at the same time to use water judiciously. The evaluation will be conducted in cooperation with Dr. Peter Waller of the University of Arizona (UofA), and thus a collaborative agreement has established with the UofA. Initial research activities are underway, focusing on collection of published data and ADWR records to establish baseline conditions that will enable future comparisons of BMP program participating and non-participants. Results of this research will be used by ADWR to guide future policy development. 5. Describe the major accomplishments to date and their predicted or actual impact. Many producers in the western United States who use surface irrigation apply fertilizer, dissolving it in the irrigation water (fertigation), without adequate guidelines, because it is an inexpensive method of fertilizer application, and fertilizer can be applied regardless of the size of the plants in the crop. A fertigation experiment, conducted by U. S Water Conservation Laboratory scientists on narrow sloping closed-end border strips planted to date palms, compared different strategies for the timing of the injection of a bromide tracer. It was found for the conditions of the experiment that injection during the entire irrigation produced the most uniform distribution of fertilizer across the field. In modeling the phenomenon, ditches formed when the border dikes were created, transmitted water to the end to the end of the field more quickly than predicted by commonly used one-dimensional (1-D) models. As a result, a 1-D model did not predict the fate of the bromide accurately. The results of this field study indicate that more complete 2-D models are necessary to predict the fate of fertilizer injected into surface irrigation systems. These results will be of value in the development of guidelines for effective and efficient fertigation that both saves on fertilizer costs and protects ground and surface waters from contamination. Supports National Program 201, Water Resources Management, Problem Area 2 Irrigation Water Management A key factor in the desorption of phosphorus from entrained sediments into the surrounding irrigation stream is the residence time of each sediment size fraction in the water. By following the fate of entrained and deposited fractions along characteristic curves, representing the trajectories of individual cross sections of the flow as they are swept along, gaining and losing sediment, it proves possible to capture the residence time for each fraction. With desorption rates provided by collaborators in Kimberly, ID (Northwest Irrigation and Soils Research Laboratory, ARS), engineers at the U. S. Water Conservation Laboratory calculate the total desorption from a cross section as it traverses the length of a furrow. When incorporated into a complete model of phosphorus transport in irrigation water, this can be used to predict results for what-if scenarios and so lead to management strategies for minimizing agricultural phosphorus tailwater runoff into receiving streams. Supports National Program 201, Water Resources Management, Problem Area 6 Integrated Soil Erosion and Sedimentation Technologies Prediction equations for soil erosion in overland flow, originally developed for rivers and streams where transport of sand and gravel are the main concern, do not properly predict sediment transport for furrows and overland flow where small sand and silt particles are the primary concern. Research engineers at the U.S. Water Conservation laboratory discovered that Laursen's sediment transport capacity equation predicted negative transport capacities for small particle sizes -- a physical impossibility. It was shown that if one calculated the shear on the very small sediments in accord with the principles of modern fluid mechanics, which account for zones of laminar and turbulent flow adjacent to the boundary, then transport capacities would remain positive for all particle sizes. This method will provide more reasonable predictions of soil erosion for agricultural soil subjected to furrow irrigation or rainfall-induced overland flow. Supports National Program 201, Water Resources Management, Problem Area 6 Integrated Soil Erosion and Sedimentation Technologies Alfalfa is a profitable crop for farmers throughout the U.S., widely used in dairy production and as feed for horses, but in arid and semiarid areas the water use by alfalfa is high. A study aimed at improved water management was conducted in Arizona by the U.S. Water Conservation Laboratory (USWCL). Results show that irrigation water applications to alfalfa can be reduced by as much as 10% from the current irrigation scheduling-software-generated recommendations without significant loss of yield and resulting, also, in less contamination and irrigation water leached below the root zone. These results will be useful to producers, consultants, other researchers, and policy makers. Supports National Program 201, Water Resources Management, Problem Area 2 Irrigation Water Management Natural Resources Conservation Service (NRCS) engineers applying USWCL border-irrigation design-aid software have occasionally been frustrated by hardwired limits on trial values of design variables, intended to steer inexperienced users away from potentially troublesome combinations of values. USWCL engineers have re-examined these limits and the penalties for selecting inappropriate values. A two-tiered system was introduced into the software allowing experienced designers to select their own limits on input variables, while guiding the less experienced toward "safer" values. The adjustments make application of the design aid software more attractive to action agencies and thus help to put more science into the design and management of surface irrigation systems aimed at increasing uniformity and efficiency. Supports National Program 201, Water Resources Management, Problem Area 2 Irrigation Water Management Field evaluations of surface-irrigation performance depend upon measurements of advance and recession, which are often difficult to obtain under field conditions. USWCL engineers designed a remotely operated device for measuring when the water arrived (advance) and when it disappeared from the surface (recession), which would make it unnecessary to enter the wet field. Development has been completed on a new fiber-optic advance and opportunity time sensor with no moving parts. The device can be used by action agencies and state-funded mobile irrigation laboratories for irrigation evaluations and infiltration parameter estimates, with the ultimate goal of improving irrigation management in surface systems. Supports National Program 201, Water Resources Management, Problem Area 2 Irrigation Water Management 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? The first major ALARC software release, winSRFR, Version 1 occurred in FY2006. Subsequent releases are expected almost annually. Adoption of our released products is dependent on the convenience of their use. Their durability depends on their flexibility in accommodating new surface- irrigation practices as these arise in the field. Supports National Program 201, Problem Area 2 Irrigation Water Management In a significant transfer of technology, the source code for SRFR was shared with University of Melbourne, Victoria, Australia for inclusion in their dairy-production model (irrigated pasture) Customary responses to inquiries about our software, especially from abroad, continued in FY 2006. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Bjorneberg, D.L., Westermann, D.T., Aase, J.K., Clemmens, A.J., and Strelkoff, T.S. 2006. Sediment and phosphorus transport in irrigation furrows. Ag Professional Weekly, July, 50(7):40-42.

Impacts
(N/A)

Publications

  • Bautista, E., Schlegel, J.L., Strelkoff, T., Clemmens, A.J., Strand, R.J. 2006. An integrated software package for simulation, design, and evaluation of surface irrigation systems. Proceedings of the World Water and Environmental Resources Congress. 10 pp. (CD unpagenated)
  • Strelkoff, T., Clemmens, A.J. 2005. Transport capacity for eroded silts in irrigation furrows. Journal of Hydraulic Engineering. 13(10):921-926.


Progress 10/01/04 to 09/30/05

Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Water supplies are under increasing competition, with urban and environmental water needs often taking precedence over agricultural needs. In the American West, it is becoming clear from tree-ring data that the last 100 years have represented an unusually wet era; the region now appears to be returning to normal, harsh desert conditions. Furthermore, nonpoint-source pollution from irrigated agriculture reduces the quality of groundwater and surface water supplies. Water quality concerns and curtailment of irrigation water rights have already reduced the amount of water available for irrigated agriculture, and it is likely that this trend will continue into the foreseeable future. Because such a large portion of agricultural production comes from irrigated agriculture, the quantity and quality of inexpensive food supplies are threatened by losses of water quantity and quality. At the same time, world population predictions suggest that irrigated agriculture will have to maintain or increase production to satisfy future needs for food and fiber. This research project is helping to develop economically viable and environmentally sustainable irrigation systems through improved water and fertilizer management practices and systems. Surface irrigation is the main focus of this research, because it is an economically viable option for many field crops; it is practiced on more than 50% of the irrigated land in the U.S. and more than 80% worldwide. While surface irrigation efficiencies are often low, they can be significantly improved. With such large quantities of water earmarked for irrigation, even small percentage gains in efficiency can make a big difference. Improved water and nitrogen management techniques, including satisfaction of total maximum daily load (TMDL) requirements, will be central to preventing the projected world food crisis, while maintaining a healthy natural environment. Our research program is aimed ultimately at providing guidelines for surface irrigation management and design, including application of agricultural chemicals in the irrigation water. This program is characterized by a strong computer software component, for what-if event simulations and as aids in management and design. Complementary field studies provide real-world bases for simulation theory, as well as calibration and verification of computer models. They also provide empirical bases for system recommendations in advance of complete computer modeling capability. Specific objectives for the 5-year project duration are: - Develop validated software for: - estimation of field parameters; - design and management aids; - simulation of surface-irrigation hydraulics. Validated surface-irrigation models incorporating fate and transport of sediments, phosphorus, and nitrogen on and off site. Guidelines for water and nutrient management in surface irrigation for minimizing introduction of nitrogen into surface and ground waters, while maintaining soil fertility, crop yields, farm profitability and sustainability. Develop guidelines for design and management of drain-back and other surface-drained level basins for improved water use. Our research supports National Program 201, Water Quality and Management, falling under Component 2, Irrigation and Drainage Management. It deals with both agricultural water conservation, and the effects of irrigated agriculture on the environment. The National Program problem areas and goals addressed are Problem Area 2.3 (Water Conservation Management), Goal 2.3.3 (Agricultural Water Conservation and Environmental Quality) and also Problem Area 2.6 (Erosion on Irrigated Land), Goal 2.6.2 (Irrigation/Erosion Model). We are collaborating with the Northwest Irrigation and Soils Research Laboratory, ARS, Kimberly, ID, on a joint ARS-CSREES NRI-funded project, Simulation and Validation of Phosphorus Loading in Furrow Irrigation Tailwater. Likewise, we are collaborating with the University of Arizona, Yuma Agricultural Center under the reimbursable agreement, Nitrogen and Phosphorus Transport under Surface Irrigation, partially funded by CSREES/NRI, Development of Guidelines for Fertigation in Surface Irrigation Systems. Through specific cooperative agreements, we are collaborating with Oregon State University on Comparison of Surface Irrigation Measurement- Based Infiltration Parameter Estimation Methods, and with Louisiana State University on Evaluation of Level Basin Irrigation in High Rainfall Zones. 2. List the milestones (indicators of progress) from your Project Plan. Year 1 (FY 2002): - Platform languages selected for WinSRFR, our Windows-based integrated surface-irrigation hydraulics software - Sediment transport component of WinSRFR completed Year 2 (FY 2003): - Field evaluation component of WinSRFR completed - Phosphorus fate and transport component of WinSRFR completed - Field studies of nitrogen uniformity and efficiency completed - Field studies of surface drained level basins completed Year 3 (FY 2004): - Furrow-design component of WinSRFR completed - Sediment and phosphorus models validated and calibrated - Preliminary guidelines for fertigation with surface irrigation - Guidelines prepared for drainback level basins Year 4 (FY 2005): - Nitrogen transport in the surface stream modeled. Soil-water chemistry model added - Modeling of surface drained level basins completed Year 5 (FY 2006): - WinSRFR released - Nitrogen-transport model validated and calibrated - Final guidelines on nitrogen fertigation with surface irrigation completed - Guidelines for design and management of surface drained level basins completed Our current project plans only extend through mid FY07. 3a List the milestones that were scheduled to be addressed in FY 2005. For each milestone, indicate the status: fully met, substantially met, or not met. If not met, why. 1. Furrow-design component of WinSRFR completed. Theory and application strategy completed 2005, along with a stand-alone spread sheet and expositional papers. Programming into WinSRFR is pending restructuring of our old stand-alone surface-irrigation software into the new, integrated WinSRFR curently underway. Milestone Substantially Met 2. Complete modeling of fate and transport of nitrogen in the irrigation stream. An advective fertigation module added to SRFR, the USWCL surface- irrigation simulation program. A stand-alone advection-diffusion model based on SRFR hydraulic output completed; described in a doctoral thesis. Milestone Substantially Met 3. Couple SRFR nitrogen component to soil-water/chemistry model (HYDRUS, UNSATCHEM). Progress slowed by resource limitations. The modeling of the fate of nitrogen in the surface stream needed to be completed first. Preliminary work on linking SRFR output to HYDRUS has been done but not for both SRFR and nitrogen transport. Unless proposed joint research with University of California at Riverside is funded, present staffing levels will not allow this project to go forward until the project plan is updated in FY2007/8 Milestone Not Met Progress slowed by resource limitation (human,fiscal,equipment, etc. 4. Complete modeling of surface-drained level basins. Progress slowed by resource limitations. At current staffing levels, this project is postponed to an updated project plan beginning 2007. Milestone Not Met Progress slowed by resource limitation (human,fiscal,equipment, etc. 3b List the milestones that you expect to address over the next 3 years (FY 2006, 2007, and 2008). What do you expect to accomplish, year by year, over the next 3 years under each milestone? Our current project plans extend only through the beginning of FY07. Several of the milestones in the current project plans have not been met, so a discussion of additional research plans for FY06 is included as well as future research into FY07 and 08. Year 5 (FY2006) Validate and calibrate nitrogen model -- furrows. Results from experiments conducted in FY2004 will be used to calibrate the nitrogen transport model for furrows in FY2006. Guidelines on nitrogen fertigation in furrows completed. By mid FY 2006 data analysis of all experiments conducted prior to that time should be completed, allowing development of guidelines for furrows with and without tailwater runoff. Guidelines will be made available to action agencies. Complete field-evaluation component. We are planning to refine, extend, and convert the stand-alone spreadsheet application for field-parameter evaluation stemming from a collaborative study with Oregon State University to a module in our integrated software package, WinSRFR. Initial versions of the estimation procedures will be incorporated in a beta release of WinSRFR, late in calendar 2005, with a formal release in 2006 Complete WinSRFR. A release is planned in FY2006, with capabilities comparable to the current stand alone SRFR, BASIN, and BORDER software as well as the rudimentary versions of field evaluation (parameter estimation). The convenience of the integrated software, especially in guiding the user through the difficult prerequisite of estimating infiltration and roughness, should greatly encourage the application of its science to solving problems of inefficient use of water for irrigation. Complete sediment transport component of SRFR. Planned for FY06. With this model, it will be possible to run what-if scenarios permitting comparisons of tentative management protocols to better control sediment movement on and off site in furrow-irrigated fields in erodible soils. Simplified management strategy for basin irrigation. In a new study requested by the U.S. Bureau of Reclamation (Yuma, AZ) USWCL engineers will develop a simple slide-card for irrigators delineating the relationship between (measured) time that a stream advances to the midpoint in a basin and the appropriate time to cut off the inflow stream to just provide for the crop needs everywhere with as little excess as possible. With irrigators cutting off on such a schedule, the most efficient application for the extant field and inflow conditions will be realized. Completion is expected in FY2006. Assuming that the subsequent project plan continues the research along its present course, we anticipate accomplishing in: Year 6 (FY2007): Guidelines for the design and management of surface-drained level basins. Intensive field experiments will be undertaken in Louisiana in FY06 under a cooperative agreement with Louisiana State University. We expect preliminary guidelines to result from that and earlier studies in FY07. We expect that effort to provide useful results for drainback level basins also. Complete phosphorus fate and transport. Completion of a model of phosphorus entrainment from non-eroding soil and its transport by advection and diffusion in the irrigation stream is planned for FY07, as is desorption from sediments entrained into an erosive stream. The model will allow calculation of phosphorus concentrations in furrow tailwater under a variety of what-if scenarios for selection of management protocols minimizing offsite discharges of nutrients into receiving water bodies. New release of WinSRFR expected in FY 2007, reflecting advances in SRFR since its current release in 2001. In addition, the new release will reflect a USWCL program of enhancements to accommodate whole fields, and even farms, and over all the irrigations expected in a season, rather than a single irrigation in a single furrow, border, or basin. In FY2007, we plan to accommodate sets of furrows, irrigated at one time, and responding differently, because of spatial variability in a field. This more realistic view will allow action agencies equipped with the software to do a better job recommending design and management options to their clients for achieving effective and efficient irrigation. Chemical database prepared from field and laboratory experiments for application to modeling the decomposition of unstable compounds such as urea in the surface stream and interaction of reactive solutes such as ammonium and phosphate with the soil surface. The model is intended for application to fertigation management with surface irrigation. Model of border strips with side ditches completed. Simulation of the 2-dimensional flow patterns in a border strip fed both from its upstream end, uniformly across its width, and from the sides, laterally, from water advancing rapidly down shallow side channels, ahead of the stream in the border strip. This is a prerequisite to modeling the post- irrigation distribution of fertilizer injected into the inflow stream. Year 7 (FY2008) Model of surface-drained level basins completed. Design and management guidelines for growers prepared. Calibration and validation of phosphorus fate and transport model completed with field data collected by cooperating researchers at Northwest Irrigation and Soils Research Laboratory. Complete validated and calibrated nitrogen model -- borders. Early efforts to calibrate and validate the model failed because side ditches in the experimental border -- a common feature in border irrigation -- constituting a two-dimensional feature not addressed in the one- dimensional model, proved of greater significance than contemplated. With the two-dimensional aspects modeled in FY 2007, the validation and calibration of the nitrogen module can go forward. Modules that predict the hydrolysis of urea in irrigation water and the interaction of ammonium and phosphate added to the chemical transport model, FY 2008. 4a What was the single most significant accomplishment this past year? Many producers in the western United States who use surface irrigation apply fertilizer, dissolving it in the irrigation water (fertigation), without adequate guidelines, because it is an inexpensive method of fertilizer application, and fertilizer can be applied regardless of the size of the plants in the crop. A fertigation experiment, conducted by U. S Water Conservation Laboratory scientists on narrow sloping closed-end border strips planted to date palms, compared different strategies for the timing of the injection of a bromide tracer. It was found for the conditions of the experiment that injection during the entire irrigation produced the most uniform distribution of fertilizer across the field. In modeling the phenomenon, ditches formed when the border dikes were created, transmitted water to the end to the end of the field more quickly than predicted by commonly used one-dimensional (1-D) models. As a result, a 1-D model did not predict the fate of the bromide accurately, indicating that more complete 2-D models are necessary to predict the fate of fertilizer injected into surface irrigation systems. These results will be of value in the development of guidelines for effective and efficient fertigation that both saves on fertilizer costs and protects ground and surface waters from contamination. 4d Progress report. A collaborative study with Oregon State University compared existing methods for determining infiltration parameters from surface irrigation observations. Several procedures, modified for spreadsheet application were programmed and tested with field data sets collected by OSU. Initial results are documented in a Masters thesis completed in June 2005. Although the results revealed important differences among the methods tested, uncertainties in the data made interpretation of some results difficult. The integrated surface-irrigation software, WinSRFR, is approaching a state suitable for beta testing. It has been provided with capabilities comparable to the current stand alone SRFR, BASIN, and BORDER software, while rudimentary versions of field- parameter estimation are being converted from the current spreadsheet format for the beta testing. An advection-dispersion model that uses hydraulic-simulation output from SRFR has been developed for predicting the transport of chemicals injected into the water stream during irrigation. The new model accounts for variable water velocity, surface roughness, and infiltration. An initial calibration of the model has been completed using data from a field experiment with closed and open ended furrows. Changes in peak shapes of pulses injected into the water along the length of the furrow agree well with the field data once the hydraulics of the irrigation are calibrated. In the research effort to provide guidelines for efficient injection of fertilizer into irrigation water in surface systems, a field experiment was conducted at Maricopa, Arizona in which pulses of bromide and rhodamine dye were injected. Bromide is a non-reactive tracer and rhodamine is weakly absorbed onto the soil surface. Soil moisture readings were made before and after the irrigation and soil samples were taken before and after the experiment for bromide analysis. Bromide concentrations of the irrigation water were also made during the experiment using bromide sensitive electrodes. Water samples and soil samples have been analyzed for bromide but have not yet been analyzed for rhodamine. The bromide results have been used to calibrate an advection- dispersion model linked to SRFR. Use of the reactive tracer, rhodamine, will provide data allowing current chemical transport models linked to SRFR to be extended to incorporate soil interaction with reactive solutes such as phosphate and ammonium. Progress was made on a simulation model for entrainment and transport of phosphorus in surface-irrigation streams from bed materials that remain in place. The heart of the model consists in tracking cross sections of water that take up phosphorus as they sweep down a furrow with the velocities of those cross sections provided by the existing hydraulic model, SRFR. The advection and diffusion components of the chemical simulation are treated separately, but both are applied to the moving cross sections. The advection part has been completed, while the diffusion part, it is expected, will be treated by the end of calendar year 2005. A project is being conducted by Louisiana State University in cooperation with Angelina Plantation, Monterey, LA and the U.S. Water Conservation Lab. A series of fields, both sloped and level, with cotton, rice and soybeans, have been selected for comparing conventional sloping fields with precision-graded (level and sloping) fields prepared with surface drainage systems. The fields, their internal ditches, drainage outlets, water supplies, tensiometers, etc. are being mapped with GPS coordinates for entry into a GIS system. Flow meters have been installed on all water supply wells for these fields. Several fields have also been instrumented with a variety of sensors, including: soil moisture sensors (tensiometers, Water Marks, Echo soil moisture loggers), sensors for evaporation and evapotransiration (EasyPans, ET gages), rain gauges (automatic and manual recording), and weather stations. The Arkansas Scheduler is being used to schedule irrigations on cotton and soybeans. Advance and recession measurement during irrigation were made on several fields, but data collection proved difficult, and few irrigation events occurred due to high rainfall. Automatic advance and recession timers did not perform as well as expected. Attempts are being made to measure surface drainage from these fields, but this has proven to be more difficult than expected. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. A key factor in the desorption of phosphorus from entrained sediments into the surrounding irrigation stream is the residence time of each sediment size fraction in the water. By following the fate of entrained and deposited fractions along characteristic curves, representing the trajectories of individual cross sections of the flow as they are swept along, gaining and losing sediment, it proves possible to capture the residence time for each fraction. With desorption rates provided by collaborators in Kimberly, ID (Northwest Irrigation and Soils Research Laboratory, ARS), engineers at the U. S. Water Conservation Laboratory calculate the total desorption from a cross section as it traverses the length of a furrow. When incorporated into a complete model of phosphorus transport in irrigation water, this can be used to predict results for what-if scenarios and so lead to management strategies for minimizing agricultural phosphorus tailwater runoff into receiving streams. Prediction equations for soil erosion in overland flow, originally developed for rivers and streams where transport of sand and gravel are the main concern, do not properly predict sediment transport for furrows and overland flow where small sand and silt particles are the primary concern. Research engineers at the U.S. Water Conservation laboratory discovered that Laursen's sediment transport capacity equation predicted negative transport capacities for small particle sizes -- a physical impossibility. It was shown that if one calculated the shear on the very small sediments in accord with the principles of modern fluid mechanics, which account for zones of laminar and turbulent flow adjacent to the boundary, then transport capacities would remain positive for all particle sizes. This method will provide more reasonable predictions of soil erosion for agricultural soil subjected to furrow irrigation or rainfall-induced overland flow. Alfalfa is a profitable crop for farmers throughout the U.S., widely used in dairy production and as feed for horses, but in arid and semiarid areas the water use by alfalfa is high. A study, aimed at improved water management was conducted in Arizona by the U.S. Water Conservation Laboratory (USWCL). Results show that irrigation water applications to alfalfa can be reduced by as much as 10% from the current irrigation scheduling-software-generated recommendations without significant loss of yield and resulting, also, in less contamination and irrigation water leached below the root zone. These results will be useful to producers, consultants, other researchers, and policy makers. Natural Resources Conservation Service (NRCS) engineers applying USWCL border-irrigation design-aid software have occasionally been frustrated by hardwired limits on trial values of design variables, intended to steer inexperienced users away from potentially troublesome combinations of values. USWCL engineers have re-examined these limits and the penalties for selecting inappropriate values. A two-tiered system was introduced into the software allowing experienced designers to select their own limits on input variables, while guiding the less experienced toward "safer" values. The adjustments make application of the design aid software more attractive to action agencies and thus help to put more science into the design and management of surface irrigation systems aimed at increasing uniformity and efficiency. Field evaluations of surface-irrigation performance depend upon measurements of advance and recession, which are often difficult to obtain under field conditions. USWCL engineers designed a remotely operated device for measuring when the water arrives (advance) and when it disappears from the surface (recession), which would make it unnecessary to enter the wet field. Development has been completed on a new fiber-optic advance and opportunity time sensor with no moving parts. The device can be used by action agencies and state-funded mobile irrigation laboratories for irrigation evaluations and infiltration parameter estimates, with the ultimate goal of improving irrigation management in surface systems. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Beyond the customary responses to inquiries about our software, especially from abroad, no specific instances of tech transfer are noted for FY 2005. Software releases are expected in FY2006 and 2007. Adoption of our released products is dependent on the convenience of their use. Their durability depends on their flexibility in accommodating new surface-irrigation practices as these arise in the field. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Elstein, D., Suszkiv, J., and Wood, M. 2004. The best of both worlds? Fertigation is an efficient way for many farmers to grow crops crops. Agricultural Research, 52(11):18-19. November Unsigned article. 2004 .Research aims to improve fertigation. AG Weekly, Twin Falls, Idaho, November 13, pg. 17

Impacts
(N/A)

Publications

  • Adamsen, F.J., Hunsaker, D.J., Perea, H. 2005. Border strip fertigation: distribution of water and bromide. Transactions of the ASAE. 48(2):529-540
  • Clemmens, A.J., Bjorneberg, D.L. 2005. New furrow flume for high sediment loads. Applied Engineering in Agriculture, 21(2)227-236.


Progress 10/01/03 to 09/30/04

Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Water supplies are under increasing competition, with urban and environmental water needs often taking precedence over agricultural needs. In the American West, it is becoming clear from tree-ring data that the last 100 years have represented an unusually wet era; the region now appears to be returning to normal, harsh desert conditions. Furthermore, nonpoint-source pollution from irrigated agriculture reduces the quality of groundwater and surface water supplies. Water quality concerns and curtailment of irrigation water rights have already reduced the amount of water available for irrigated agriculture, and it is likely that this trend will continue into the foreseeable future. Because such a large portion of agricultural production comes from irrigated agriculture, the quantity and quality of inexpensive food supplies are threatened by losses of water quantity and quality. At the same time, world population predictions suggest that irrigated agriculture will have to maintain or increase production to satisfy future needs for food and fiber. This research project is helping to develop economically viable and environmentally sustainable irrigation systems through improved water and fertilizer management practices and systems. Surface irrigation is the main focus of this research, because it is an economically viable option for many field crops; it is practiced on more than 50% of the irrigated land in the U.S. and more than 80% worldwide. While surface irrigation efficiencies are often low, they can be significantly improved. With such large quantities of water earmarked for irrigation, even small percentage gains in efficiency can make a big difference. Improved water and nitrogen management techniques, including satisfaction of total maximum daily load (TMDL) requirements, will be central to preventing the projected world food crisis, while maintaining a healthy natural environment. Our research program is aimed ultimately at providing guidelines for surface irrigation management and design, including application of agricultural chemicals in the irrigation water. This program is characterized by a strong computer software component, for what-if event simulations and as aids in management and design. Complementary field studies provide real-world bases for simulation theory, as well as calibration and verification of computer models. They also provide empirical bases for system recommendations in advance of complete computer modeling capability. Specific objectives for the 5-year project duration are: - develop validated software for: - estimation of field parameters; - design and management aids; - simulation of surface-irrigation hydraulics. Validated surface-irrigation models incorporating fate and transport of sediments, phosphorus, and nitrogen on and off site. Guidelines for water and nutrient management in surface irrigation for minimizing introduction of nitrogen into surface and ground waters, while maintaining soil fertility, crop yields, farm profitability and sustainability. Develop guidelines for design and management of drain-back and other surface-drained level basins for improved water use. Our research supports National Program 201, Water Quality and Management, falling under Component 2, Irrigation and Drainage Management. It deals with both agricultural water conservation, and the effects of irrigated agriculture on the environment. The National Program problem areas and goals addressed are Problem Area 2.3 (Water Conservation Management), Goal 2.3.3 (Agricultural Water Conservation and Environmental Quality) and also Problem Area 2.6 (Erosion on Irrigated Land), Goal 2.6.2 (Irrigation/Erosion Model). We are collaborating with the Northwest Irrigation and Soils Research Laboratory, ARS, Kimberly, ID, on a joint ARS-CSREES NRI-funded project, Simulation and Validation of Phosphorus Loading in Furrow Irrigation Tailwater. Likewise, we are collaborating with the University of Arizona, Yuma Agricultural Center under the reimbursable agreement. Nitrogen and Phosphorus Transport under Surface Irrigation, partially funded by CSREES/NRI, Development of Guidelines for Fertigation in Surface Irrigation Systems. Through specific cooperative agreements, we are collaborating with Oregon State University on Comparison of Surface Irrigation Measurement- Based Infiltration Parameter Estimation Methods, and with Louisiana State University on Evaluation of Level Basin Irrigation in High Rainfall Zones. 2. List the milestones (indicators of progress) from your Project Plan. Year 1 (FY 2002): - Platform languages selected for WinSRFR, our Windows-based integrated surface-irrigation hydraulics software - Sediment transport component of WinSRFR completed Year 2 (FY 2003): - Field evaluation component of WinSRFR completed - Phosphorus fate and transport component of WinSRFR completed - Field studies of nitrogen uniformity and efficiency completed - Field studies of surface drained level basins completed Year 3 (FY 2004): - Furrow-design component of WinSRFR completed - Sediment and phosphorus models validated and calibrated - Preliminary guidelines for fertigation with surface irrigation issued - Guidelines prepared for drainback level basins Year 4 (FY 2005): - Nitrogen transport in the surface stream modeled. Soil-water chemistry model added - Modeling of surface drained level basins completed Year 5 (FY 2006): - WinSRFR released - Nitrogen-transport model validated and calibrated - Final guidelines on nitrogen fertigation with surface irrigation completed - Guidelines for design and management of surface drained level basins completed 3. Milestones: A. List the milestones that were scheduled to be addressed in FY 2004. How many milestones did you fully or substantially meet in FY 2004, and indicate which ones were not fully or substantially met, briefly explain why not, and your plans to do so. Note: the number of SY on this project has been reduced from what was on the original project plans. Funding levels did not allow us to maintain the same number of SYs over the life of the project. Furrow-design component of WinSRFR completed Theory for this component is in place. Programming is pending restructuring of our old stand-alone surface-irrigation software into the new, integrated WinSRFR curently underway. Sediment and phosphorus models validated and calibrated Transport of sediment with a single representative particle size is completed; extension to a mix of sizes is only partly done -- the programming proved more complicated than foreseen. Completion is foreseen by end of calendar year 2004. Modeling of phosphorus desorption from a non-eroding bed is expected to be completed late in FY2004. Modeling of phosphorus adsorbed to sediment depends on sediment modeling, and completion is not expected before FY 2005. Preliminary guidelines for fertigation with surface irrigation issued Issuance of preliminary fertigation guidelines for surface irrigation systems has been delayed. The effects of geometric complexity of border strip irrigation systems has slowed the analysis of the data and hence the development of fertigation guidelines. Thus far, only analysis of blocked-end borders and furrows has been completed. These analyses have shown a consistent pattern which will lead to guidelines for blocked-end systems. Analysis of data from a system with tailwater runoff will be continued and should lead to preliminary guidelines by the end of FY 2005. Guidelines prepared for drainback level basins Because of collaborative work with cooperators, we have shifted the focus from drainback level basins to surface-drained level basins. See this item under FY 07. We expect that effort to provide useful results for drainback level basins also. B. List the milestones that you expect to address over the next 3 years (FY 2005, 2006, & 2007). What do you expect to accomplish year by year, over the next 3 years under each milestone? Year 4 and 5 milestones are listed below with a description of the anticipated outcomes. The entire project is scheduled to be completed during FY 2006, and a new project will be developed to undergo OSQR review and subsequent implementation beginning FY 2007. Year 4 (FY 2005): Nitrogen transport in the surface stream modeled. Soil-water chemistry model added. A nitrogen transport model for the flow in the surface stream is virtually complete, though calibration and validation is not done yet. The model is capable of modeling multiple nitrogen components but currently only nitrate is modeled We are losing the graduate student involved in this project (graduation); adding the soil-water component depends on the recruitment of a replacement. A projected alternative is to collaborate with University of California Riverside in developing a linkage between SRFR and HYDRUS -- a project has been submitted by UCR for funding a joint effort. Preliminary guidelines on nitrogen fertigation with surface irrigation. Data analysis of field experiments from systems with tailwater runoff should progress sufficiently in FY 2005 for preliminary guidelines for fertigation to be issued. As in previous analyses, it is expected that analysis of field data will lead to model refinements that will expand the applicability of the model results for fertigation analysis. Modeling of surface drained level basins completed We plan to couple 1-dimensional simulation of flows in the grid of spin ditches with 2-dimensional simulations in the checkerboard of level basins supplied and drained by the ditches. Limited funding may result in this being delayed until FY06. Year 5 (FY 2006): WinSRFR released Sufficient IT personnel to complete the project are in place (FY 2004) and programming should be completed as projected. A preliminary release, integrating the functionality which exists at present in USWCL surface- irrigation stand-alone software is planned for FY 2005. Our ability to apply modern engineering principles to the design and management of surface irrigation systems is constrained by our ability to characterize infiltration and hydraulic resistance properties of irrigated fields. A research project was initiated by the U.S. Water Conservation Laboratory, in cooperation with Oregon State University, to compare the robustness and accuracy of various methodologies that have been proposed for estimating such parameters, when applied under a variety of irrigation conditions. The project, which should be completed in 2005, has initially identified and organized field irrigation data sets that will be used in the comparison, and began developing software that will be needed to conduct the analyses. The outputs of the project, mainly recommendations of specific estimation procedures and guidelines for the concomitant capture and processing of data required will lead to incorporation of the best methods into the WinSRFR software, to be completed in 2006. The new software will assist irrigation specialists in their efforts to develop management and design recommendations for improving irrigation performance. Nitrogen-transport model validated and calibrated Early efforts to calibrate and validate the model (in FY 2004) failed because side ditches in the experimental border, constituting a 2- dimensional feature not addressed in the 1-d model, proved of greater significance than contemplated. In addition, the sampling frequency used in the previous field experiments was not sufficient to calibrate the longitudinal dispersion coefficient. New experiments are in the design stage (FY 2004) and should be completed before the end of FY 2004. Final guidelines on nitrogen fertigation with surface irrigation completed. By mid FY 2006 data analysis of all experiments conducted prior to that time should have been completed, which should allow development of final guidelines for blocked furrow and border with or without tailwater runoff. Guidelines will be made available to action agencies. Guidelines for design and management of surface drained level basins completed We have collected some field data in Arkansas and Louisiana and have established a cooperative agreement with Louisiana State University for assistance in the collection of more field data, from which recommendations will be made. Results are not expected until FY 06 or FY 07. Assuming that the subsequent project plan continues the research along its present course, we anticipate accomplishing in: Year 6 (FY 2007): Design, management and simulation software are currently (2004) oriented to a single event -- a single irrigation, in one furrow, border, or basin. This event is tacitly assumed representative of results in a given field. But engineers assisting farmers/irrigators need to think in terms of realistic, whole fields or even farms, and over all of the irrigations expected in a season. We plan to expand WinSRFR to accommodate the broader point of view, starting with sets of furrows, irrigated at one time, and responding differently, because of spatial variability in a field We plan to begin developing procedures that take into account the stochastic nature of infiltration and roughness parameters in FY 2007, with results expected in later years. Fertigation management with surface irrigation: The current and past work with fertigation has used bromide as a surrogate for nitrate because nitrate has the greatest potential for contamination of surface water and groundwater. However, the most common source of fertilizer is urea ammonium nitrate solutions and the current and previous work does not describe the behavior of the ammonium and urea nitrogen components of the fertilizer materials that are commonly in use. Beginning in FY 2007, field and laboratory experiments will be designed and conducted to add interactions of the ammonium and urea components to the irrigation models. In subsequent years, the irrigation model will be linked to a soil chemistry model. 4. What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY 2004 (one per Research Project): A key factor in the desorption of phosphorus from entrained sediments into the surrounding irrigation stream is the residence time of each sediment size fraction in the water. By following the fate of entrained and deposited fractions along characteristic curves, representing the trajectories of individual cross sections of the flow as they are swept along, gaining and losing sediment, it proves possible to capture the residence time for each fraction. With desorption rates provided by collaborators in Kimberly, ID (Northwest Irrigation and Soils Research Laboratory, ARS), engineers at the U. S. Water Conservation Laboratory calculate the total desorption from a cross section as it traverses the length of a furrow. When incorporated into a complete model of phosphorus transport in irrigation water, this can be used to predict results for what-if scenarios and so lead to management strategies for minimizing agricultural phosphorus tailwater runoff into receiving streams. B. Other Significant Accomplishment(s), if any: None C. Significant activities that support special target populations None D. Progress Report: PHOSPHORUS (P) DESORPTION IN SURFACE IRRIGATION Analysis of desorption data from a wide range of laboratory experiments at Kimberly led to an empirical relation quantifying the dependence of desorption rate on time, soil test phosphorus, concentration of sediment in the water, and concentration of phosphorus in the water. Initial analysis of the tests focusing on the effect of P concentration in water on P desorption from suspended sediment showed that P concentrations of 0.05, 0.1 and 0.2 ppm in water had little impact on the amount of P desorbed from suspended sediment. Additional studies quantified the concentration of soil-solution P in simulated irrigation water as a function of soil test P. The information provides input to models of P entrainment into irrigation streams. To investigate phosphorus losses under different management options for surface irrigation with its relatively quiescent conditions, a computer program was written to model the entrainment and transport of phosphorus in a flume with a noneroding soil bed enriched with the chemical. The effects of diffusion were found to be relatively small, with entrainment and advection being the principle mechanisms involved. Calibration in the future, by comparison of measured and calculated phosphorus concentrations in the tailwater, is expected to yield the actual entrainment rate. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Prediction equations for soil erosion in overland flow, originally developed for rivers and streams where transport of sand and gravel are the main concern, do not properly predict sediment transport for furrows and overland flow where small sand and silt particles are the primary concern. Research engineers at the U.S. Water Conservation laboratory discovered that Laursen's sediment transport capacity equation predicted negative transport capacities for small particle sizes -- a physical impossibility. It was shown that if one calculated the shear on the very small sediments in accord with the principles of modern fluid mechanics, which account for zones of laminar and turbulent flow adjacent to the boundary, then transport capacities would remain positive for all particle sizes. This method will provide more reasonable predictions of soil erosion for agricultural soil subjected to furrow irrigation or rainfall-induced overland flow. Alfalfa is a profitable crop for farmers throughout the U.S., widely used in dairy production and as feed for horses, but in arid and semiarid areas the water use by alfalfa is high. A study, aimed at improved water management was conducted in Arizona by the U.S. Water Conservation Laboratory (USWCL). Results show that irrigation water applications to alfalfa can be reduced by as much as 10% from the current irrigation scheduling-software-generated recommendations without significant loss of yield and resulting, also, in less contamination and irrigation water leached below the root zone. These results will be useful to producers, consultants, other researchers, and policy makers. Natural Resources Conservation Service (NRCS) engineers applying USWCL border-irrigation design-aid software have occasionally been frustrated by hardwired limits on trial values of design variables, intended to steer inexperienced users away from potentially troublesome combinations of values. USWCL engineers have re-examined these limits and the penalties for selecting inappropriate values. A two-tiered system was introduced into the software allowing experienced designers to select their own limits on input variables, while guiding the less experienced toward "safer" values. The adjustments make application of the design aid software more attractive to action agencies and thus help to put more science into the design and management of surface irrigation systems aimed at increasing uniformity and efficiency. Field evaluations of surface-irrigation performance depend upon measurements of advance and recession, which are often difficult to obtain under field conditions. USWCL engineers designed a remotely operated device for measuring when the water arrived (advance) and when it disappeared from the surface (recession), which would make it unnecessary to enter the wet field. Development has been completed on a new fiber-optic advance and opportunity time sensor with no moving parts. The device can be used by action agencies and state-funded mobile irrigation laboratories for irrigation evaluations and infiltration parameter estimates, with the ultimate goal of improving irrigation management in surface systems. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Conversations with cooperators suggest that farmers continue to convert from traditional graded (furrow and border) to level-basins (including drainback and grid-supplied-and-drained variations) in various parts of the country. Reasons expressed for this conversion include improved water management and reduced irrigation labor costs. Expansion of this technology in humid areas is hampered by local NRCS rules which do not support surface irrigation systems with zero-grade. Hence, farmers are converting their systems in the humid areas exclusively with their own financial resources. Surface irrigation design and operating guidelines and tools have been transferred to a variety of clients through personal visits (e.g., NRCS, cooperative extension, experiment stations, state mobile irrigation labs), software used world wide (available on USWCL web pages -- with a link from the NRCS Water and Climate Center web page), and through technical presentations at irrigation meetings and conferences. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. "Efficient Irrigation Important to Farmers," LSU Ag Center News, June 2, 2004, LSU AgCenter Communications, Baton Rouge, Louisiana 70894-5100, 4 pp. (ARS contribution p.3)

Impacts
(N/A)

Publications

  • Clemmens, A.J., Westermann, D.T., Strelkoff, T., Bjorneberg, D.L. Phosphorus loading in furrow irrigation tailwater. In: Proceedings of the World Water and Environmental Resources Congress. June 27-July 1, 2004, Salt Lake City, Utah. 2004 CDROM.
  • Strelkoff, T.S., Tamimi, A.J., Clemmens, A.J. Two-dimensional basin flow with irriegular bottom configuration. Journal of Irrigation and Drainage Engineering. ASCE 129(6):391-401. 2003
  • Clemmens, A.J., Strelkoff, T.S., Playan, E. Field verification of two- dimensional surface irrigation model. Journal of Irrigation and Drainage Engineering. ASCE 129(6):402-411. 2003


Progress 10/01/02 to 09/30/03

Outputs
1. What major problem or issue is being resolved and how are you resolving it? There are serious concerns about the sustainability of irrigated agriculture in the United States and in many areas of the world. At the same time, world population predictions suggest that irrigated agriculture will have to maintain or increase production to satisfy future needs for food and fiber. Water supplies are under increasing competition, with urban and environmental water needs often taking precedence over agricultural needs. Further, nonpoint source pollution from irrigated agriculture can reduce the quality of groundwater and surface water supplies. This research project is helping to develop economically viable and environmentally sustainable irrigation systems through improved water and fertilizer management practices and systems. Surface irrigation is the main focus of this research, because surface irrigation is practiced on more than 50% of the irrigated land in the U.S. and more than 80% worldwide, and because surface irrigation efficiencies continue to be low and can be significantly improved. Surface irrigation continues to be an economically viable option for many low-value crops. 2. How serious is the problem? Why does it matter? Water quality concerns and curtailment of irrigation water rights have already reduced the amount of water available for irrigated agriculture, and it is likely that this trend will continue into the foreseeable future. Because such a large portion of agricultural production comes from irrigated agriculture, the quantity and quality of inexpensive food supplies are threatened by losses of water quantity and quality. The problem is nearing critical proportions worldwide. Improved water and nitrogen management techniques, including satisfaction of total maximum daily load (TMDL) requirements, will be central to preventing the projected world food crisis, while maintaining a healthy natural environment. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? The reported research supports National Program 201, Water Quality and Management. The project falls under Component 2, Irrigation and Drainage Management. It deals with both agricultural water conservation, and the effects of irrigated agriculture on the environment. The National Program problem areas and goals addressed are Problem Area 2.3 (Water Conservation Management), Goal 2.3.3 (Agricultural Water Conservation and Environmental Quality) and also Problem Area 2.6 (Erosion on Irrigated Land), Goal 2.6.2 (Irrigation/Erosion Model). We are collaborating with the Northwest Irrigation and Soils Research Laboratory, ARS, Kimberly, ID, on a joint ARS-CSREES NRI-funded project, Simulation and Validation of Phosphorus Loading in Furrow Irrigation tailwater. Likewise, we are collaborating with the University of Arizona, Yuma Agricultural Center. under the reimbursable agreement. Nitrogen and Phosphorus Transport under Surface Irrigation, partially funded by CSREES/NRI, Development of Guidelines for Fertigation in Surface Irrigation Systems. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishment during FY 2003:Prediction equations for soil erosion with overland flow, originally developed for rivers and streams where transport of sand and gravel are the main concern, do not properly predict sediment transport for furrows and overland flow where small sand and silt particles are the primary concern. Research engineers at the U.S. Water Conservation laboratory discovered that Laursen's sediment transport capacity equation predicted negative transport capacities for small particle sizes ? a physical impossibility. It was shown that if one calculated the shear on the very small sediments in accord with the principles of modern fluid mechanics, which account for zones of laminar and turbulent flow adjacent to the boundary, then transport capacities would remain positive for all particle sizes. This method will provide more reasonable predictions of soil erosion for agricultural soil subjected to furrow irrigation or rainfall-induced overland flow. B. Other Significant Accomplishment(s), if any: C. Significant Accomplishments/Activities that Support Special Target Populations None D. Progress Report IRRIGATION SYSTEM EVALUATION The fiber-optic advance and opportunity time sensor, developed in prior years has been upgraded with a sensor to turn off the display to save battery life. We have also discussed commercialization of this device with a CRADA partner. In addition, we have extended this concept of detecting the presence of water to produce a digital depth sensor. A prototype has been constructed for testing in the lab. We are in the process of producing a field prototype version that we can test in the field. The CRADA partner has expressed more interest in this device and may cooperate with us on setting this device up for field testing. Durability and ease of construction are the factors that might limit commercialization and thus will be the focus of the field tests. FERTIGATION Efficient injection of fertilizer into irrigation water in surface systems depends on predicting post-irrigation chemical distribution. Fertigation experiments were conducted in the Coachella Valley Irrigation District in California. Testing of samples from FY02 are complete and data analysis begun. Analysis of water and soil samples from FY03 are under way. Data from FY02 show that application uniformity of the water was 0.7 to 0.8. Application uniformity of bromide tracer ranged from 0.15 to 0.6. Injection over the entire irrigation gave the best application uniformity. Timing refinements are needed to improve performance. MODELING SOIL MOISTURE AND CHEMICAL TRANSPORT WITH SURFACE IRRIGATION Predicting chemical transport under surface irrigation requires linking soil-water flow, chemistry, and surface-flow models. A first step in linking the soil moisture and chemistry model, HYDRUS (ARS, Riverside, CA) , to SRFR (ARS, Phoenix, AZ) was made by using a time dependent hydraulic head from a border strip water-depth hydrograph calculated by SRFR for input to HYDRUS. It proved necessary to modify HYDRUS to account for the cutoff of water supply to the soil as the surface water recedes, while allowing access of soil pores to the atmosphere as moisture is redistributed in the soil following recession. MODELING UNSTEADY INFILTRATION FROM FURROWS A simple and fast alternative to formally linking soil-moisture models (HYDRUS) with furrow-hydraulics models (SRFR) is an algorithm in SRFR designed to approximate infiltration with a variable wetted perimeter. HYDRUS-2D was used to simulate furrow infiltration at various wetted perimeters and furrow spacings through accurate solution of the Richards equation for unsaturated flow in a homogeneous, isotropic soil medium. The results were compared with the SRFR algorithm and also a well known NRCS approximation. In the limited range of cases tested, the SRFR algorithm was found to consistently underpredict infiltration, while the NRCS formula consistently overpredicted it. MODELING SOIL EROSION AND PHOSPHORUS TRANSPORT Coding the sediment transport module in SRFR continues. The anomalous negative transport capacities calculated for very small particles by the Laursen formula have been eliminated by the correction of an inconsistency in its derivation, but, still, the calculated transport capacities are suspiciously low. The problem of extrapolation beyond the range of empirical data remains. The hope is that there is sufficient physical basis for the formula to allow limited extrapolation. Experimental corroboration with the field studies at ARS, Kimberly, ID, will either confirm or condemn this approach. MEASURING SOIL EROSION AND PHOSPHORUS TRANSPORT Laboratory tests at ARS, Kimberly, ID, cooperating with USWCL, showed phosphorus (P) quickly released from suspended sediment to the water. Field tests showed most sediment was transported as small aggregates (<0. 05 mm for a silt loam soil); the P concentrations associated with each sediment size were similar. Diffusion of phosphorus, P, from furrow soil did not appear to be the main mechanism adding dissolved P to furrow flow. Desorption of P from transported sediment seems to contribute the largest portion of dissolved P to furrow water. Most of the P in the tailwater is associated with sediment which may or may not settle out, but any P dissolved in the water typically remains with the tailwater, to flow to the receiving river. PHOSPHORUS DESORPTION IN SURFACE IRRIGATION Two sets of experiments have been performed in a flume with various water depths and velocities over a phosphorus-enriched soil surface and with neither infiltration nor erosion. Analysis of the differing entrainment results in the two sets is under way, with the difference in ambient temperatures (summer and late fall) as a likely cause. Infiltration, controlled by a porous drain at constant negative pressure, will be studied next. Partially complete design for the drain is based on simulations of soil moisture flow from the bulk water on the soil surface to the bulk water in the porous pipe, via solution of the Richards equation (HYDRUS-2D, ARS, Riverside, CA). GRID-SUPPLIED AND DRAINED LEVEL BASINS A study was initiated in collaboration with Louisiana State University to develop design and management recommendations for grid supplied and drained level basin systems. Such systems are being adopted in Louisiana and Arkansas, even though they are not sanctioned in state NRCS guidelines, due to concern over drainage of excess rainfall. Data is being collected on a farm on which many traditional graded furrow systems have been converted to level basins. Such data will help document claims made by the farmers about the production and cost advantages of level basins as compared to graded furrows. SURFACE IRRIGATION PARAMETER ESTIMATION SOFTWARE (SIPES) We have continued the development of software for estimation of surface irrigation field parameters. The software will assist action agencies, such as NRCS, with their parameter-estimation needs and will provide a vehicle for comparing alternative methods. Progress has been made in the development of screens and data-file structures needed to capture the inputs required by the various methods. Only simple volume-balance methods have been programmed so far, and initial studies have been conducted to contrast the effectiveness of those methods and to assess their limitations. ERRORS INHERENT IN SIMPLIFIED INFILTRATION-PARAMETER ESTIMATION METHODS Simple methods for estimating infiltration in surface irrigation from measured stream parameters require estimates of average cross-sectional area of the surface water flows. A simulation study was conducted to determine the degree of error in estimated time to infiltrate a target depth as a consequence of errors in assumed average cross section or measured advance times. For soils well characterized by the Merriam and Clemmens Time Rated Infiltration Families, the errors generated in the corresponding One-Point method proved moderate and well behaved even for infiltration times well in excess of the advance time. And as expected, the larger the field slope, the smaller the error. IMPLICATIONS OF UNCERTAIN FIELD PARAMETERS FOR BORDER IRRIGATION MANAGEMENT A study was performed on the effect of variations in infiltration characteristics (relative to the values assumed in design) on border irrigation performance. The study is part of a broader effort aimed at developing design and management recommendations given uncertain design information. Current results suggest that border systems, if properly designed, have some tolerance for erroneous design information. However, compensating for the effect of such uncertainties requires an in-depth understanding of the hydraulic characteristics of the particular system. MEASURING FURROW FLOW AND EROSION In prior studies of furrow erosion, the flumes used to measure water flow in the furrow restricted flow, so that sediment deposited upstream from the flume. Placing the flume lower caused difficulties in getting downstream water and sediment samples, in addition to causing flume submergence: placing them higher resulted in deposition of sediment upstream. A new flume was designed for furrow erosion studies by engineers at the U.S. Water Conservation Lab, Phoenix, AZ and the Northwest Irrigation and Soils Research Lab, Kimberly, ID, such that changes in upstream depth and velocity are minimized throughout the range of flows. Prototypes were constructed with sheet steel and a commercial version was manufactured in fiberglass by a local manufacturer of flumes. Studies on the performance of these flumes is ongoing. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Alfalfa is a profitable crop for farmers throughout the U.S., widely used in dairy production and as feed for horses, but in arid and semiarid areas the water use by alfalfa is high. A study, aimed at improved water management was conducted in Arizona by the U.S. Water Conservation Laboratory (USWCL). Results show that irrigation water applications to alfalfa can be reduced by as much as 10% from the current irrigation scheduling-software-generated recommendations without significant loss of yield and resulting, also, in less contamination and irrigation water leached below the root zone. These results will be useful to producers, consultants, other researchers, and policy makers. Natural Resources Conservation Service (NRCS) engineers applying USWCL border-irrigation design-aid software have occasionally been frustrated by hardwired limits on trial values of design variables, intended to steer inexperienced users away from potentially troublesome combinations of values. USWCL engineers have re-examined these limits and the penalties for selecting inappropriate values. A two-tiered system was introduced into the software allowing experienced designers to select their own limits on input variables, while guiding the less experienced toward Asafer@ values. The adjustments make application of the design aid software more attractive to action agencies and thus help to put more science into the design and management of surface irrigation systems aimed at increasing uniformity and efficiency. Field evaluations of surface-irrigation performance depend upon measurements of advance and recession, which are often difficult to obtain under field conditions. USWCL engineers designed a remotely operated device for measuring when the water arrived (advance) and when it disappeared from the surface (recession), which would make it unnecessary to enter the wet field. Development has been completed on a new fiber-optic advance and opportunity time sensor with no moving parts. The device can be used by action agencies and state-funded mobile irrigation laboratories for irrigation evaluations and infiltration parameter estimates, with the ultimate goal of improving irrigation management in surface systems. 6. What do you expect to accomplish, year by year, over the next 3 years? In general, in future years, increased coordination between the modeling and field studies is planned. In FY2004 simulations of post-irrigation fertigation-chemical distributions will be extended to basins with no runoff, and compared with field results to discern the role of mixing or diffusion of the fractions, ignored in the present model. A new grower cooperator has allowed progress to accelerate. Analysis of samples from the field studies should be completed by the middle of FY04 and the data used to develop guidelines for producers to use when applying fertilizer in the irrigation water. The development of complete fertigation guidelines will require the addition of a dispersion term to the existing chemical transport model and completion of linkage to a subsurface flow model such as HYDRUS. These tasks will be the focus of the fertigation work in FY04 and FY05. During FY2004, we plan to continue development of an inexpensive sensor for shallow water depths to provide additional data for estimating field values of infiltration and roughness. We plan to seek assistance from a CRADA partner to commercialize the product. Calibration models, which account for the effects of soil salinity on the output of an inexpensive, time domain reflectometer (TDR) soil moisture sensor, will be developed by the end of FY2004, subject to time constraints. This will provide the capability of the sensor to measure more accurately soil water content in fields where high soil salinity decreases the reliability of TDR measurements. During FY2004, programming for an integrated, true Windows version of the surface-irrigation software should be under way, with a conclusion in FY2006. Acquisition of additional IT staff, expected early FY2004, should keep this project on track in accord with the Project Plan. The major part of the programming for the sediment fate and transport component of SRFR should be completed by the end of calendar 2003, with the phosphorus component following in FY2004; calibration and validation should be completed in FY2004-FY2005. In FY2004, our cooperators at ARS, Kimberly will continue to analyze field and laboratory data to develop relationships for modeling transfer of phosphorus from sediment to flowing water. Efforts will be continued during FY 2004 to equip the SRFR program with infiltration models more physically based than the purely empirical formulas now in use. Formal linkage with existing stand-alone software based on solutions of the Richards equations for soil moisture flow is expected in FY2005. Development of SIPES is planned to occur in phases reflecting the different parameter-estimation methods, with periodic releases to cooperators during FY2004 and beyond. A newly developing cooperative agreement with Oregon State University may provide graduate-student help with programming the different phases. The approaches will be assessed and recommendations made also via informal collaborative agreements stemming from scientists' participation in the ASCE Task Committee on surface-irrigation parameter estimation, to which USWCL scientists contribute substantially. We expect to complete a comprehensive report on this work in 2005. We will continue the theoretical studies on field-parameter uncertainty in design and management of level basins and borders through FY2004, with the objective of developing graphical tools that can be used for assessing the effect of uncertain infiltration inputs on irrigation performance. In FY2004 we will also expand the work to include furrow irrigation systems. Beginning in FY2004, we will pursue field studies in collaboration with NRCS to assess performance of actual NRCS surface irrigation designs and the contribution of field-wide and seasonal variation. By the end of FY05, we expect to have sufficient field data on the performance of level basins in Louisiana and Arkansas to provide guidelines for grid-supplied and drained level basins. Field data collection efforts have been hampered by the distance to field sites (>1000 miles). We expect additional data to be collected during FY04 and FY05, with assistance from Louisiana State University, ARS Baton Rouge, and NRCS, Little Rock, AR. These data collections will provide support to efforts to document the performance of these irrigation/drainage systems and help to validate the mathematical models developed. We expect to produce a mathematical model to describe irrigation and drainage from grid-supplied level basins by the end of FY06, in cooperation with Louisiana State University. We are currently investigating alternative formulations of the governing equations to deal with the complexity of the grid-supplied systems, which our current 1- dimensional models cannot describe and which cannot be adequately handled by our existing 2-dimensional formulations either. By the end of FY04, we expect to complete the numerical analyses to provide some preliminary guidelines for drain-back level basins. These will be augmented with further analysis through use of the mathematical models under development by the end of FY06. 7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Conversations with cooperators suggest that farmers continue to convert from traditional graded (furrow and border) to level-basins (including drainback and grid-supplied-and-drained variations) in various parts of the country. Reasons expressed for this conversion include improved water management and reduced irrigation labor costs. Expansion of this technology in humid areas is hampered by local NRCS rules which do not support surface irrigation systems with zero-grade. Hence, farmers are converting their systems in the humid areas exclusively with their own financial resources. Surface irrigation design and operating guidelines and tools have been transferred to a variety of clients through personal visits (e.g., NRCS, cooperative extension, experiment stations, state mobile irrigation labs), software used world wide (available on USWCL web pages -- with a link from the NRCS Water and Climate Center web page), and through technical presentations at irrigation meetings and conferences. 8. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: This does not replace your peer-reviewed publications listed below). "Innovative irrigation technologies promise more crop for the drop," by Jimmy Reed, pp. 12-13, 18, Cotton Farming, Feb. 2003. (p. 18 discusses ARS research).

Impacts
(N/A)

Publications

  • Strelkoff, T., Bautista, E., Clemmens, A.J. 2003. Errors inherent in the simplified infiltration parameter estimation. United States Committee of Irrigation and Drainage Engineering Conference. p. 735-745.
  • Perea, H., Strelkoff, T., Simunek, J., Bautista, E., Clemmens, A.J. 2003. Unsteady furrow infiltration in the light of the richards equation. United States Committee of Irrigation and Drainage Engineering Conference. p.625- 636.
  • Bautista, E., Strelkoff, T., Clemmens, A.J. 2003. Border irrigation management implications of imprecise infiltration parameter estimates. United States Committee On Irrigation And Drainage Conference. 603-614
  • Tamimi, A.H., Clemmens, A.J., Bautista, E., Strelkoff, T. 2003. Sipes - surface irrigation parameter estimation software. United States Committee of Irrigation and Drainage Engineering Conference. p. 615-624.
  • Abbasi, F., Adamsen, F.J., Hunsaker, D.J., Feyen, J., Shouse, P., Van Genuchten, M. Effects of flow depth on water flow and solute transport in furrow irrigation: field data analysis. Journal of Irrigation and Drainage Engineering. 129(4):237-246. July/Aug. 2003.
  • Zerihun, D., Sanchez, C.A., Farrell-Poe, K.L. Adamsen, F.J., Hunsaker, D.J. Performance indices for surface N fertigation. J. Irrig. and Drain. Engineering. 2003. v. 129. p. 173-183.


Progress 10/01/01 to 09/30/02

Outputs
1. What major problem or issue is being resolved and how are you resolving it? There are serious concerns about the sustainability of irrigated agriculture in the United States and in many areas of the world. At the same time, world population predictions suggest that irrigated agriculture will have to maintain or increase production to satisfy future needs for food and fiber. Water supplies are under increasing competition, with urban and environmental water needs often taking precedence over agricultural needs. Further, nonpoint source pollution from irrigated agriculture can reduce the quality of groundwater and surface water supplies. This research project is helping to develop economically viable and environmentally sustainable irrigation systems through improved water and fertilizer management practices and systems. Surface irrigation is the main focus of this research, because surface irrigation is practiced on more than 50% of the irrigated land in the U.S. and more than 80% worldwide, and because surface irrigation efficiencies continue to be low and can be significantly improved. Surface irrigation continues to be an economically viable option for many low-value crops. 2. How serious is the problem? Why does it matter? Water quality concerns and curtailment of irrigation water rights have already reduced the amount of water available for irrigated agriculture, and it is likely that this trend will continue into the foreseeable future. Because such a large portion of agricultural production comes from irrigated agriculture, the quantity and quality of inexpensive food supplies are threatened by losses of water quantity and quality. The problem is nearing critical proportions worldwide. Improved water and nitrogen management techniques, including satisfaction of total maximum daily load (TMDL) requirements, will be central to preventing the projected world food crisis, while maintaining a healthy natural environment. 3. How does it relate to the national Program(s) and National Program Component(s) to which it has been assigned? The reported research supports National Program 201, Water Quality and Management. The project falls under Component 2, Irrigation and Drainage Management. It deals with both agricultural water conservation, and the effects of irrigated agriculture on the environment. The National Program problem areas and goals addressed are Problem Area 2.3 (Water Conservation Management), Goal 2.3.3 (Agricultural Water Conservation and Environmental Quality) and also Problem Area 2.6 (Erosion on Irrigated Land), Goal 2.6.2 (Irrigation/Erosion Model). We are collaborating with the Northwest Irrigation and Soils Research Laboratory, ARS, Kimberly, ID, on a joint ARS-CSREES NRI-funded project, Simulation and Validation of Phosphorus Loading in Furrow Irrigation tailwater. Likewise, we are collaborating with the University of Arizona, Yuma Agricultural Center. under the reimbursable agreement.Nitrogen and Phosphorus Transport under Surface Irrigation, partially funded by CSREES/NRI, Development of Guidelines for Fertigation in Surface Irrigation Systems. 4. What was your most significant accomplishment this past year? A. Single Most Significant Accomplishment during FY 2002: Alfalfa is a profitable crop for farmers throughout the U.S., widely used in dairy production and as feed for horses, but in arid and semiarid areas the water use by alfalfa is high. A study, aimed at improved water management was conducted in Arizona by the U.S. Water Conservation Laboratory (USWCL). Results show that irrigation water applications to alfalfa can be reduced by as much as 10% from the current irrigation scheduling-software-generated recommendations without significant loss of yield and resulting, also, in less contamination and irrigation water leached below the root zone. These results will be useful to producers, consultants, other researchers, and policy makers. B. Other Significant Accomplishment(s), if any: Natural Resources Conservation Service (NRCS) engineers applying USWCL border-irrigation design-aid software have occasionally been frustrated by hardwired limits on trial values of design variables, intended to steer inexperienced users away from potentially troublesome combinations of values. USWCL engineers have re-examined these limits and the penalties for selecting inappropriate values. A two-tiered system was introduced into the software allowing experienced designers to select their own limits on input variables, while guiding the less experienced toward ?safer? values. The adjustments make application of the design aid software more attractive to action agencies and thus help to put more science into the design and management of surface irrigation systems aimed at increasing uniformity and efficiency. Field evaluations of surface-irrigation performance depend upon measurements of advance and recession, which are often difficult to obtain under field conditions. USWCL engineers designed a remotely operated device for measuring when the water arrived (advance) and when it disappeared from the surface (recession), which would make it unnecessary to enter the wet field. Development has been completed on a new fibre-optic advance and opportunity time sensor with no moving parts. The device can be used by action agencies and state-funded mobile irrigation laboratories for irrigation evaluations and infiltration parameter estimates, with the ultimate goal of improving irrigation management in surface systems. C. Significant Accomplishments/Activities that Support Special Target Populations None D. Progress Report FERTIGATION Efficient injection of fertilizer into irrigation water fertigation) in surface systems has been hampered by the difficulty of predicting post- irrigation distributions of the chemical. An experimental modification was made to the surface-irrigation simulation program, SRFR, to track the successive fractions of applied inflow -- some with injected chemical in accord with the injection schedule -- assuming no mixing of the fractions. A complementary analysis of farm-scale experiments near Phoenix, AZ, was completed; these utilized tracers to determine the fate of chemicals added to the irrigation water. MODELING SOIL MOISTURE AND CHEMICAL TRANSPORT WITH SURFACE IRRIGATION Predicting chemical transport under surface irrigation requires linking soil-water flow, chemistry, and surface-flow models. A first step in linking the soil moisture and chemistry model, HYDRUS (ARS, Riverside, CA) , to SRFR was made by using a time dependent hydraulic head from a furrow water-depth hydrograph calculated by SRFR as input to HYDRUS to test SRFR?s simulation of infiltration. The current focus of the investigation is the application of appropriate boundary conditions to HYDRUS to characterize the influence of variable depth and wetted perimeter in the furrow on infiltration. MODELING SOIL EROSION AND PHOSPHORUS TRANSPORT In tracking very small particle sizes, the Laursen transport-capacity formula , the best available for fine sands and silts, yields negative transport capacities. The anomaly was traced to an inconsistency between calculations of the tractive force on particles at the bed surface, which assume fully turbulent flow all the way to the bed, and the critical tractive force at incipient motion, calculation of which recognizes a laminar sublayer in the flow surrounding the small particles. Allowing a laminar sublayer in the tractive force calculations as well eliminated the negative transport capacities. MEASURING SOIL EROSION AND PHOSPHORUS TRANSPORT ARS, Kimberly, ID, cooperating with USWCL, conducted field studies on particle-size distributions in the furrow bed and flow, soil- erodibility calibration, and total sediment loads for ultimate model verification. Laboratory tests showed phosphorus quickly released from suspended sediment to the water. Field tests showed most sediment was transported as small aggregates (<0.05 mm for a silt loam soil), and phosphorus concentrations associated with each sediment size were similar. Most of the phosphorus in the furrow tailwater is associated with sediment, but any phosphorus dissolved in the water typically persists, to flow to the river. PHOSPHORUS DESORPTION IN SURFACE IRRIGATION To investigate exchanges of soil water and solute with runoff under the relatively quiescent conditions of surface irrigation (no precipitation), a 2.4 m-long instrumented flume 100 mm wide was constructed with a soil bed such that phosphorus desorbed into a non-erosive, initially phosphorus-free inflow could be measured in the runoff. Initial calibration experiments have been performed with local (Avondale) and imported (Portneuf -- Idaho) soil. By placing phosphorus-fertilized soil layers at various depths in the soil bed, the existence of a mixing layer and its dependence on the flow turbulence will be investigated. GRID-SUPPLIED AND DRAINED LEVEL BASINS In Southeast Arkansas, in cooperation with the NRCS, an irrigation event was observed on a large level basin constructed with an internal grid of channels for water supply and drainage. Field soil elevations were measured with a GPS unit mounted on a small 4-wheel all-terrain vehicle. The elevations were recorded while driving through the field and along the network of channels. The advancing front was also measured by driving along the front line with the 4-wheeler. The field was seeded to rice, so no data on drainage have been collected. SURFACE IRRIGATION PARAMETER ESTIMATION SOFTWARE (SIPES) Construction has begun on a menu-driven Windows program with a number of estimation methods for the field parameters required as input to surface- irrigation simulation and management software. The methods requiring less field data generally make up for the lack by a series of assumptions. The purpose of the software, so-far equipped with 4 estimation methods, is two-fold: 1) to provide action agencies such as NRCS with immediate assistance with their parameter-estimation needs, and 2) to provide a vehicle for studying the tradeoffs between expensive data-gathering efforts and inaccuracies engendered by the assumptions. SENSITIVITY OF SURFACE-IRRIGATION MANAGEMENT TO FIELD PARAMETERS A complementary theoretical study was performed for level basins on the effect of variations in infiltration and roughness parameters (relative to the values assumed in design) upon management recommendations. The study showed that when actual advance time is more than assumed, basing inflow cut off on actual advance distance leads to minimal departures from predicted uniformities and efficiencies. But if actual advance time is less than predicted, cutoff based on a given time may be the better approach, independent of variations in infiltration, roughness, and inflow rate. WATER AND NITROGEN MANAGEMENT OF GUAYULE A study was initiated on guayule, a latex and rubber plant native to the southwestern U. S. and Mexico and on the verge of commercialization. A site with two very different background fertility levels was selected to determine the daily water use requirements of the crop and the response of guayule to nitrogen management. The crop has been established and the field instrumented with time domain reflectance (TDR) devices and neutron access tubes to follow soil moisture levels. In addition, soil samples have been taken and analyzed to document fertility. 5. Describe your major accomplishments over the life of the project, including their predicted or actual impact? This project is the replacement project for Irrigated Farm Management, terminated in January, 2002. During the life of that project, the research consisted of both software development -- for simulation, design, and management -- and field studies -- for providing the scientific background for management recommendations. SRFR software, for simulating flow in borders, basins, and furrows in accordance with a wide variety of scenarios and conditions was first released in 1998. Modifications to increase its range of capabilities, including erosion, transport and deposition of bed sediments, facilitation of comparisons between measured and simulated irrigation performance, and tracking fractions of inflow containing various levels of injected fertilizer have appeared in subsequent years. A two- dimensional model of flow in large, imperfectly leveled basins with point inlets has been constructed and validated in a commercial field of the Gila River Indian Community. The design-aid programs, BASIN for traditional level basins, and BORDER for sloping border strips with tail- water runoff, both based on databases of previously run simulations, are also available for downloading on the USWCL web site. BASIN was recently enhanced to allow flow control to be exercised on the basis of stream- advance behavior, as commonly practiced, rather than on the more theoretical and rigid time-based inflow. BORDER features displays of performance contours which show what level of performance is possible, given prevailing field conditions, as well as what combinations of design and management parameters will yield a given performance level. The experimental design-aid software, FURROW, employs the same displays as BORDER, but develops its database of simulations interactively and is therefore far more flexible in permissible scenarios than the latter, with its static database. These software products can be a great asset to action agencies and irrigation specialists seeking optimal solutions to water-conservation and return-flow-quality problems. At the same time, all of the software requires input of extant field conditions -- infiltration and roughness. As a first step in providing needed guidance, existing methods were summarized and organized on the basis of their measured-data requirements. Additional theoretical work clarifying the various components of irrigation water use, describes how these components affect irrigation efficiency through case studies, and describe where and when efficiency improvements provide real water conservation. This information should be useful to individual and regional water project managers, government agencies with water management authority, consultants, extension specialists, and farmers/ irrigators. An important component of the field studies has focused on crop water use in both ambient conditions and also under increased atmospheric CO2 (in anticipation of potential global climate changes). Tests under normal conditions led to the development of yield/water-use relationships in cotton, lesquerella, wheat, and other traditional and new crops. They have also clarified the role of soil evaporation, associated with irrigation and precipitation, in irrigation efficiencies and in leading to better predictions of total crop ET. Tests on a number of small, inexpensive, easily automated TDR (time domain reflectance) soil- moisture sensors showed that moisture readings were affected by soil- salinity levels; relationships were developed for correcting the effects of salinity. It was found that mechanically compacting the surfaces of level furrows was effective in increasing irrigation uniformity and efficiency in soils with high and varied infiltration and roughness. In the area of water-use efficiency, it has long been known from studies in pots, that cotton yields could be increased with less total water applied, if the frequency of irrigation was substantially increased. USWCL researchers were able to confirm this response in the field, when irrigation was accomplished by modern surface-irrigation techniques, e.g., with level basins. Field experiments on spatial variability showed that yield differences within a field are strongly influenced by irrigation water-application uniformity, and that to improve water use efficiency, surface irrigation systems should be designed for separate management zones within the field. Scheduling and water-use research was tempered, however, by a related study of grower practices showing that some opt to schedule irrigations in standard blocks based on physical and labor constraints, rather than strictly on crop water demands. In recent years, an increasing emphasis has been placed on chemical fate and transport in surface irrigation systems. Work in FY2001 showed that runoff of applied irrigation water decreased from an average of 21% under every-furrow irrigation to 13% under every-other-furrow irrigation; however, deep percolation and nitrate leaching below the cotton root zone were increased with every-other-furrow irrigation, which increased the potential for nitrate contamination of ground water. It was concluded that cotton growers using either furrow-irrigation practice, implementing a tailwater recovery system and improving irrigation scheduling would potentially increase the irrigation efficiency significantly and reduce over-irrigation and nitrate leaching. First efforts were aimed at developing guidelines for nitrogen fertilization, in particular, by injection into the irrigation water (fertigation). Field-scale studies in farm-scale surface irrigation systems utilized tracers to determine the fate of chemicals added to irrigation water. Initial results showed that the distribution of chemical within the field can be manipulated by adjusting the onset and duration of fertilizer additions to the irrigation water stream. Furthermore, it was demonstrated that year-round crop rotations can be used to keep nitrogen incorporated in plant material and prevent movement of nitrate to groundwater. Ultimately, this work will develop management practices that will minimize nitrogen off site discharges of nitrogen. 6. What do you expect to accomplish, year by year, over the next 3 years? In general, in future years, increased coordination between the modeling and field studies is planned. In FY2003 simulations of post-irrigation fertigation-chemical distributions will be extended to basins with no runoff, and compared with field results to discern the role of mixing or diffusion of the fractions, ignored in the present model. The field work should be completed by the end of FY2003 and the data used to develop guidelines for producers to use when applying fertilizer in the irrigation water. When work on level basins is completed the work will be expanded to sloping borders over a range of soil conditions and system designs which should yield results in FY2004. During FY2003-FY2004, we plan to add depth-measuring capabilities to the remote advance and opportunity time sensor, to provide additional data for estimating field values of infiltration and roughness. Calibration models, which account for the effects of soil salinity on the output of an inexpensive, time domain reflectometer (TDR) soil moisture sensor, will be developed by the end of FY2004. This will provide the capability of the sensor to more accurately measure soil water content in fields where high soil salinity decreases the reliability of TDR measurements. During FY2003, an integrated, true Windows version of the surface- irrigation software will be undertaken, with a conclusion in FY2006 During FY2002/2003 the erosion and phosphorus fate and transport components of SRFR should be completed, with calibration and validation completed in FY2004 Efforts will be continued during FY 2002-3 to link the SRFR program with infiltration models more physically based than the purely empirical formulas now in use; to be completed in 2004. SIPES should be completed and released in FY2003. Initial runs should lead to the first recommendations for field-parameter estimation. A final report with guidelines is intended for 2005. The impact of parameter-estimation uncertainty on surface irrigation design and management recommendations will be studied in border strips and furrows in FY2002-3. We plan to develop design procedures that incorporate statistical measures of uncertainty. Guidelines for adjusting system operation to account for uncertainty should be completed by 2005. Modeling of grid-supplied and drained level basins is to be undertaken in FY2003 and completed in FY2005, in parallel with field studies in the lower Mississippi Valley. 7. What technologies have been transferred and to whom? When is the technology likely to become available to the end user (industry, farmer other scientist)? What are the constraints, if known, to the adoption durability of the technology? The drain-back level basin system, developed by our research group, continues to expand in acreage. The method has been presented at national irrigation meetings. We continue to provide assistance to consultants on the design and operation of these systems. This technology has recently expanded into Louisiana, where farmers have adapted it to include surface drainage due to high rainfall conditions. Acreage of surface-drained level basins in Louisiana is expanding rapidly. Image processing methods for digital cameras to determine flower counts, etc. have been presented at scientific meetings and requests from other ARS scientists for more information have been answered. Surface irrigation design and operating guidelines and tools have been transferred to a variety of clients through personal visits (e.g., NRCS, cooperative extension, experiment stations, state mobile irrigation labs), software (models were made available on NRCS Water and Climate Center and USWCL web pages and are used world wide) and through technical presentations at irrigation meetings and conferences. The current erosion component has been made available for downloading by cooperating researchers for evaluation and potential contributions.

Impacts
(N/A)

Publications

  • Strelkoff, T.S., Fernandez-Gomez, R., Mateos, L., Giraldez, J.V., Clemmens, A.J. On tracking sediment particle sizes in furrow-irrigation induced erosion for modeling phosphorus transport. Proceedings 2002 USCID/EWRI Conference -- Energy, Climate, Environment and Water, San Luis Obispo, July 10-13, p.423 - 433. 2002.
  • Bautista, E., Strelkoff, T. S., Clemmens, A. J. Sensitivity of surface irrigation to infiltration parameters: implications for management. p.p. 475-485. Proceedings 2002 USCID/EWRI Conference -- Energy, Climate, Environment and Water, San Luis Obispo, CA, July 10-13, 2002. p. 475 - 485.
  • El-Haddad, Z., Clemmens, A. J., El-Ansary, M., Awad, M. Influence of cultural practices on the performance of long level basins in Eygpt. Irrigation and Drainage Systems. 2001. 15(4). p. 327-353.
  • Rice, R. C., Hunsaker, D. J., Adamsen, F. J., Clemmens, A. J. Irrigation and nitrate movement evaluation in conventional and alternate-furrow irrigated cotton. Transactions of the ASAE. 44(3):555-568. 2001.