Source: UNIVERSITY OF FLORIDA submitted to
EFFECTIVENESS OF SILVICULTURE BEST MANAGEMENT PRACTICES FOR FOREST FERTILIZATION IN PINE STRAW PRODUCTION TO PROTECT WATER QUALITY IN FLORIDA
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0222955
Grant No.
(N/A)
Project No.
FLA-NFC-005053
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2010
Project End Date
Jun 30, 2015
Grant Year
(N/A)
Project Director
Minogue, P.
Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
North Florida Research and Education Center, Quincy
Non Technical Summary
In 2009 two large-scale, replicated studies were established in mid-rotation slash pine (Pinus elliottii L.) plantations in North Florida at locations with soils having contrasting leaching potential to evaluate and assess the effectiveness of current forest fertilization BMPs in reducing nonpoint source pollution. The effects of straw removal on soil physical and chemical properties, leaching potential and nutrient budgets are being examined in a long term study, with existing and projected funding until June 2014. A secondary integrated objective is to estimate the magnitude and geographic extent of pine straw production, the amount, type, and rates of fertilizer applied in this practice, and to provide training and education programs for practitioners of forest fertilization.
Animal Health Component
20%
Research Effort Categories
Basic
80%
Applied
20%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020110101025%
1120210205025%
1230611107025%
1330680106025%
Goals / Objectives
1. Determine the environmental fate of N and P following annual fertilization for four years using a wide range of applied (DAP) through large-scale, replicated research at each of two locations with contrasting leaching and sorption potential to evaluate and assess the effectiveness of current forest fertilization BMP's to reduce nonpoint source pollution, as is consistent with EPA's "iterative process" for long-term BMP development. 2. Compare leaching potential, soil physical properties, and nutrient budgets for fertilization in raked and non-raked stands to refine forest fertilization BMP's and provide new information regarding the efficient use of fertilizers in pine straw production in the Coastal Plain. 3. Determine tree growth and pine needle yield responses following a wide range of N+P fertilization rates to determine cost-effective fertilization practices for sites representing extremes in potential for soil sorption and leaching of applied nutrients. 4. Develop models to explain nutrient leaching as a function of soil physical and chemical properties, soil and atmospheric hydrology, soil and atmospheric temperature, and forest stand level nutrient dynamics (nutrient cycling), through a balance-sheet approach in raked versus un-raked forest stands. 5. Estimate the extent, location and magnitude of pine straw production as well as the amount, rates and timing of fertilization for this practice within the region. 6. Provide pertinent information in support of training and education programs for fertilization practices associated with pine straw production.
Project Methods
Long-term, replicated research plots were established in 2008-2009 at two locations with contrasting nutrient leaching and soil sorption potential, within the region in Florida where pine straw raking is common place. The Calhoun County site is an ultisol having sandy loam surface soils and an underlying clay B and C horizon; thus representing a site where soil sorption is high, internal drainage is limited and, therefore, leaching potential is low. The potential for groundwater contamination is also low since this site is within the confined aquifer (protected by overlying clay soils). The Suwannee County site is an entisol characterized by excessively drained sandy soils typical of the Florida Sand Ridge; representing a worst case scenario with respect to leaching potential. This area also has a high risk for groundwater contamination as it is within an area of unconfined aquifer, and the depth to groundwater is only 60-70 feet. Experimental Design: At each of the two study locations, twenty four 1/2-acre plots were established in twelve year old slash pine (Pinus elliottii) plantations to examine 8 different treatment combinations using a completely randomized design with 3 replications of treatments. The experiment is designed as a 4 x 2 factorial, with four levels of annual (February) fertilization treatment (0, 128, 256, 641 lb DAP per ac) and two levels of raking treatment (annual rake and no-rake). This design facilitates statistical tests on the interaction of fertilization and pine straw raking. The unfertilized plot for raked and un-raked treatments serves as an experimental control with respect to fertilization. Sampling: To ensure adequate buffers, all measurements and sampling (with the exception of monitoring wells) are made within a 0.20 acre "measurement plot" centered in the 0.5 acre treatment plot. Groundwater samples: To assess potential changes in groundwater quality, one well is installed in the fertilized study area and comparisons are made to one or more distant (~1,000 ft) control wells. Groundwater samples will be taken prior to fertilization and monthly throughout the project period and analyzed for NOx, TKN, NH4, and TP. Nutrient Budgets: periodic samples of nutrient content at various depths in the soil profile are analysed for NOx, TKN, NH4, TP, K, Ca, Mg, and OM. Nutrients in pine folage, litterfall and in harvested pine straw are measured periodically to construct nutrient budgets following various rates of DAP fertilization, with and without pine straw raking. Extension Outreach: To provide forest landowners and pine straw producers with pertinent information concerning cost-effective and environmentally sound fertilization practices for pine straw production we will conduct grower meetings, site tours, and produce technology transfer publications, such as web based "edis" materials. Detailed methods are available from the project manager.

Progress 07/01/10 to 06/30/15

Outputs
Target Audience:This program targets non-industrial private forest landowners (NIPFL), forest industry, the emerging biofuels industry, county extension faculty, and the Florida Forest Service, but is primarily directed towards NIPFL to sustain forest land ownership by providing new income opportunities. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?1. Post-doctoral Associate: Dr. Masato Miwa, 2009-2013. Evaluation of the effectiveness of silviculture BMPs for fertilization in pine straw production to protect water quality in Florida. 2. DoctoralResearch Assistant: Dr. Elsa Daniela Chevasco, 2010-2014. Pine straw harvesting and fertilization effects on aspects of nitrogen and phosphorus nutrition in slash pine (Pinus elliottii Engelm.) plantations. Ph.D. Awarded May, 2014. 3. Master of Science Research Assistant: Ms. Alexandria Whann, 2014-2016. Monitoring the environmental fate of nitrogen from polymer coated urea and conventional mineral fertilizers used in pine straw production in the lower Suwannee Valley of Florida. MS expected May 2016. How have the results been disseminated to communities of interest?We conducted 14 IFAS Extension workshops regarding forest fertilization in pine straw production with 699 growers attending. Post workshop surveys (8) indicated 100% of respondents (54% of attendees responded) learned something new and 51% changed fertilization practices as the result of something they learned. The two most common changes were avoidance of fertilization for potentially non-responsive pine stands and the use of the appropriate rates of nitrogen and phosphorus fertilizers (following Long and Jokela, 2012). Of those surveyed, 56% said they learned something to either reduce their input costs or increase the profitability of their pine straw operation. The most common changes among respondents included: (1) not fertilizing pine stands with high pine stem density and closed canopies (because they are not responsive), and (2) not fertilizing sites with excessively drained soils and no clay micelles, because they are not responsive and leaching of applied N and P is a potential concern. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Research Accomplishments: These studies evaluated the effectiveness of silvicultural BMPs for a wide range of diammonium phosphate (DAP) rates, which is among the most widely used fertilizers in southern forestry, largely because it conveniently provides both nitrogen (N) and phosphorus (P). As expected, the fate of applied nitrogen differed at the clayey, somewhat poorly drained Blountstown site versus the excessively drained, deep sandy Live Oak site, illustrating the need for site-specific recommendations. Fertilization resulted in poor or negative slash pine stand responses at both sites. Except for increased four-year pine diameter growth at Blountstown and increased four-year dominant and co-dominant pine height growth at Live Oak, all pine stand attributes either showed no response to fertilization or responded negatively to increasing fertilization rate.Fertilization caused significant pine mortality at both sites. These results of induced pine mortality are consistent with other reports for N+P fertilization of non-thinned, mid-rotation pine plantations with stand basal area greater than 100 sq ft ac-1 (436 sq m ha-1) (Ogden and Morris, 2004). Our user surveys indicated that about half of Florida pine straw growers are fertilizing to increase pine straw yield (Chevasco and Minogue, 2012), which can double with fertilization on some sites (Morris et al. 1992). Even though we observed a trend of increased yield with the medium (384 lb/acre) and high (641 lb/acre) DAP fertilization rates, the effect was significant only at Blountstown at three years after the first application and for the four-year average, when the high and medium DAP rates resulted in greater pine straw dry weight and bale count than the low rate or non-fertilized control. However, the increased yield at that site appears to be due in part to increased pine mortality and resultant needle cast observed with the medium and high rates. Mean pine straw dry weights and bale counts at Live Oak did not show significant differences between DAP fertilization treatments. However, at the sandy Live Oak site we observed a weak trend of increased pine straw yield with the medium and high fertilization rate. Poor responses to fertilization are not unusual during mid-rotation when pine straw harvesting occurs. In a region-wide study of fertilization and vegetation control in mid-rotation slash and loblolly pines at 13 sites in the southeast, only 54% responded positively in volume growth (Albaugh et al., 2012). The current BMPs address this point "it should be understood that not all silvicultural strategies require or can benefit from forest fertilization". Pine Straw Harvesting: Pine straw raking had no effect on pine stand growth parameters except for greater dominant and co-dominant pine height for non-raked treatments at the sandy Live Oak site.The effect of pine straw raking on foliar nutrients was only observed in 2011 and 2012 for K concentration at Blountstown, when mean foliar K concentration was greater for non-raked than for raked treatments. Annual pine straw removal had no meaningful effect on the concentration of any soil nutrient.Pine straw harvesting was not shown to have the potential to adversely affect water quality based on measures of soil nutrient leaching, but may have adverse effects on soil productivity over extended periods. Nitrogen Fertilization BMPs: Applied NH4-N in the form of DAP moved to the lowest monitored depth (60-72") at the sandy Live Oak site, but remained within 0-12" at Blountstown where a somewhat poorly drained clayey soil with high cation exchange capacity occurred.Nitrate concentrations increased following fertilization as nitrification of the supplied ammoniacal nitrogen occurred. Nitrate leaching through the soil profile was observed at both sites following each of the two sequential annual fertilizations, but was greatest following the second fertilization. This study demonstrated the potential for rapid leaching in saturated soil conditions at the Blountstown site, where soil NOx-N concentrations were greater than the non-fertilized control at two months after the first fertilization at all depths and for all DAP rates.However, mean NOx-N concentrations below 12 inch depth during this initial flux were always less than half the PQL (2.5 mg/kg), and ranged from 1.06 to 0.16 mg/kg. During the year after the first fertilization at Blountstown, mean NOx-N concentrations below 12 inch depth exceeded the PQL value only once, and ranged from 0.04 to 2.99 mg/kg. Following the second fertilization, nitrate leaching was clearly evident for the high (641 lb/acre) DAP rate to the deepest monitored depth at both sites.The medium rate (384 lb/acre) resulted in NOx-N concentrations greater than the non-fertilized control to the 36-48" depth 12 months after fertilization (MAF) at Blountstown and to 60-72" depth 9 MAF at Live Oak.The low rate (128 lb/acre) resulted in NOx-N concentrations greater than the non-fertilized control at 0-6" depth at 6 and 36 MAF at Blountstown, but was never different from the control at any depth at Live Oak. These results demonstrate greater potential leaching for repeated sequential applications of rates within the 250 lb/acre N three year BMP limit. In their review of water quality aspects, Binkley et al. (1999) emphasized the need for further studies examining effects of repeated fertilizer applications in larger scale studies. Peak NOx-N concentrations at the deepest monitored depth (60-72") were observed at six to nine months after the second application of the high DAP rate (641 lb/acre), and concentrations were significantly greater than the non-fertilized control.During that period, peak NOx-N concentrations in the deepest monitored depth were 2.75 mg/kg at Live Oak (LO) 6 MAF and 1.29 mg/kg at Blountstown (BT) 9 MAF.Concentrations remained significantly greater than the non-fertilized control (0.40 LO vs 0.07 BT) at that depth until one year after the second fertilization at Live Oak (1.04 mg/kg NOx-N) and two years after the second fertilization at Blountstown (0.55 mg/kg NOx-N).The greater sorption capacity and lesser hydraulic conductivity at Blountstown would explain the longer retention observed. Surficial groundwater NOx-N concentrations were elevated by fertilization at the clayey Blountstown site where groundwater was close to the surface (3.0-13.5 ft), but not at the sandy Live Oak site where groundwater was deeper (32.9-42.4 ft). However, during the 52 month monitoring period at Blountstown treatment well NOx-N concentrations were never greater than the reference well concentrations by more than 1.4 mg/L.This is not excessive in terms of groundwater quality and does not exceed state water quality standards. Phosphorus Fertilization BMPs: Because the DAP fertilizer rates applied were selected to provide various N amounts up to the near maximum BMP limit of 250 lb/acre N for a three year period, two applications of the high DAP rate provided 230 lb of N and 260 lb/acre elemental P, which exceeded the BMP limit of 80 lb/acre elemental P for a three year period by 180 lb, or 225%.Soil TP concentrations in the surface soil began to increase two months after the first fertilization and remained above baseline levels by two fold at Live Oak and three fold at Blountstown at three years after the second fertilization.However, no increase in soil TP concentration, as compared to the non-fertilized control, was observed below 12 inch depth during four years following the first fertilization at either site. No increase in groundwater TP concentration occurred due to fertilization.Phosphorus is not a highly mobile nutrient, but P fertilization may increase soluble organic phosphorus (SOP), which is more prone to leach.Continued monitoring for several years would be needed to ascertain the fate of applied P in this study.

Publications

  • Type: Journal Articles Status: Published Year Published: 2012 Citation: Susaeta, A.T., C.A. Gonzalez-Benecke, D.R. Carter, E.J. Jokela, T.A. Martin. 2012. Economic sustainability of pinestraw raking in slash pine stands in the southeastern United States. Ecological Economics 80:89-100.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Minogue, P.J., M. Miwa, A. Osiecka, J. Vowell, and R. Lima. 2012. Effectiveness of silvicultural BMPs in pine straw production to protect groundwater - third year results. Third University of Florida Water Institute Symposium. February 15-16, 2012. Gainesville, FL. http://waterinstitute.ufl.edu/symposium2012/abstract_detail.asp?AssignmentID=308
  • Type: Theses/Dissertations Status: Published Year Published: 2014 Citation: Chevasco, Els Daniela. 2014. Pine straw harvesting and fertilization effects on soil and plant phosphorus pools, bioavailability and potential losses in slash pine (Pinus elliotii Engelm.) plantations. Ph.D. Dissertation. University of Florida, Gainesville, FL.
  • Type: Other Status: Published Year Published: 2013 Citation: Minogue, P.J., A. Osiecka, D.K. Lauer, and M. Miwa. 2013. Effectiveness of Silviculture Best Management Practices for Forest Fertilization in Pine Straw Production to Protect Water Quality in Florida: Four Year Monitoring Results and Interpretation. Institute of Food and Agricultural Sciences, North Florida Research and Education Center, Quincy, FL, Research Report 2013-02. 131 p.
  • Type: Other Status: Published Year Published: 2016 Citation: Osiecka, A., P.J. Minogue, and E.D. Dickens. 2015. Guide to Fertilization for Pine Straw Production on Coastal Plain Sites. University of Florida Cooperative Extension Service Circular. 17 p. http://edis.ifas.ufl.edu/fr378
  • Type: Journal Articles Status: Submitted Year Published: 2016 Citation: *Chevasco, E.D., P.J. Minogue, N.B. Comerford, C.L. Mackowiak. (In Preparation). Fertilization and pine straw raking effects on foliar and straw cyclable P, P removals and soil extractable P pools in slash pine (Pinus elliottii Engelm.) plantations. (For submission Forest Ecology and Management, January 2016)


Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: A silvicultural fertilization BMP effectiveness monitoring project is being conducted at two study locations in north Florida having contrasting leaching potential to observe the environmental fate of nitrogen (N) and phosphorus (P) following application of diammonium phosphate (DAP) at various amounts, in the presence or absence of commercial annual pine straw raking. In separate studies at the two locations, a factorial design with three replications is examining the effects of two sequential February-March DAP fertilizations at four levels (providing 0/0, 22/24, 67/72, or 112/120 lb/acre N/P annually), annual raking at two levels (with, without), and the interaction of these factors on a host of soil and plant aspects of nutrient status and tree response. Groundwater monitoring wells are used to measure NOx-N, NH3-N, TKN, and TP concentrations periodically to assess leaching in the fertilized area as compared to a distant control well. An automated monitoring station within the stand is taking 15-minute readings of through-fall (precipitation under the canopy), soil temperatures and moisture contents at 6, 12, 24, 36, 48, and 60 inch depths. An automated weather monitoring station is taking 15-minute readings of precipitation, wind speed, air temperature, relative humidity, and photosynthetic active radiation (PAR) measurements at each study site to support nutrient fate modeling. In March 2013 all monitoring will be completed, which will be three years after the last fertilization event. PARTICIPANTS: (1) Individuals: PI Patrick Minogue, PD Masato Miwa, Co-PD Anna Osiecka, Colaborators - Cheryl Mackowiak, Jeffrey Vowell, Roy Lima; (2) Partner organizations: Florida Department of Environmental Protection, Florida Forest Service, Neil Land and Timber, Burch Family Farms; (3) Training: Daniela Chevasco Ph.D. candidate, School of Natural Resources and Environment, The University of Florida. TARGET AUDIENCES: Pine straw producers (owners of forest land) and State of Florida water quality regulators (BMPs) are the primary target audiences for this research. The research being conducted will also build upon scientific knowledge pertaining to the fate of applied nutrients, effects of pine straw removal on nutrient cycling within pine stands, and quantification of economic benefits and thresholds for fertilization in pine straw production. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Results from this study are supporting refinement of the Florida Silviculture BMPs to refine fertilization recommendations for pine straw production, to better understand the environmental fate of applied N and P, and to protect water quality in Florida and the region. DAP is the most widely used fertilizer in forestry, largely because it conveniently provides both N and P. This study showed that two consecutive annual applications of 128 lb DAP/ac (22 lb/ac N) increased surface soil NOx-N concentration without elevating NOx-N concentration of deeper soils (48-72 in depth), while two consecutive annual applications of 384 lb DAP/ac (67 lb/ac N) slightly increased deeper soil NOx-N concentration, and two consecutive annual applications of 641lb DAP/ac (112 lb/ac N) significantly increased deeper soil NOx-N concentration, particularly after the second annual application. Since NOx-N is a relatively stable and mobile nutrient, any fertilizer rate that significantly increases NOx-N concentration below the primary rooting zone (generally the upper 48 inches) should be avoided to protect groundwater. Nitrate leaching was more pronounced following the second fertilization in both studies. Rather than stipulating limits for a three-year period, BMPs should specify maximum annual amounts to apply, particularly since fertilizer applications in conventional silviculture are typically done every five to ten years. Annual fertilization guidelines would accommodate pine straw production, where annual fertilizations are common. This research suggests that two sequential annual applications of 112 lb N could be a threat to water quality in certain soils. While this level of fertilization is not practiced, it would be permissible under current BMPs. Since DAP fertilizer application rates were determined to provide various N amounts up to the near maximum BMP limit of 250 lb/ac N in three years, two applications of the high DAP rate also provided 120 lb/ac elemental P, which exceeded the BMP limit of 80 lb/ac elemental P in a three year period. Fertilization did not result in movement of P below the primary rooting zone or to groundwater in either study. Phosphorus is not a mobile nutrient, but P fertilization may increase soluble organic phosphorus (SOP), which is more prone to leach. Continued monitoring for several years would be needed to ascertain the fate of applied P in this study.

Publications

  • Minogue, P.J., D.K. Lauer, M. Miwa, and A. Osiecka. 2012. Preliminary results: Effectiveness of silviculture best management practices for forest fertilization in pine straw production to protect water quality in Florida - Analyses of monitoring well nutrient concentrations to three years after fertilization. Institute of Food and Agricultural Sciences, North Florida Research and Education Center, Quincy, FL, Research Report 2012-02. 15 p.
  • Minogue, P.J., M. Miwa, D.K. Lauer, and A. Osiecka. 2011. Preliminary results: Effectiveness of silviculture best management practices for forest fertilization in pine straw production to protect water quality in Florida. Institute of Food and Agricultural Sciences, North Florida Research and Education Center, Quincy, FL, Research Report 2011-02. 76 p.


Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: Research: A silvicultural fertilization BMP effectiveness monitoring project is being conducted at two study locations having contrasting leaching potential to observe the environmental fate of N and P applied at various amounts relative to BMP guidelines. Two sequential annual diammonium phosphate (DAP) fertilizations, providing 22/24, 67/72, or 112/120 lb/ac N/P, were monitored in stands with and without pine straw raking and compared to unfertilized controls. Two fertilizations using the highest DAP rate examined provided the near BMP maximum amount of N for a three year period and also provided 300% of the three year P maximum. Monitoring occurred for two years following the first fertilization and for one year after the second fertilization, which has provided short term results for a long term study. Periodic monitoring included N and P concentrations in surficial groundwater, soil nutrient concentrations at various depths, foliar nutrient concentrations, amounts and nutrient concentrations of pine straw litter, and amounts and nutrient concentrations for harvested pine straw. Tree growth responses and disease incidence were also measured periodically. Soil physical and chemical properties were assessed initially and after three years. Continuous rainfall and other weather monitoring and soil moisture and temperature monitoring at various depths was done to support modeling of applied nutrient fate. Extension: We conducted 13 workshops regarding forest fertilization in pine straw production with 664 growers attending. Post workshop surveys (7) indicated 100% of respondents learned something new, 53% changed fertilization practices as the result of something they learned. The two most common changes were the use of lower rates and more frequent applications. Multimedia Web-based Educational Materials: (1) Minogue, P.J. 2010. Financial returns for integrated pine straw and timber production. University of Florida, Institute of Food and Agricultural Science. http://nfrec.ifas.ufl.edu/contact/PatMinogue.shtml; (2) Minogue, P.J. 2010. Overview of pine straw production in north Florida. University of Florida, Institute of Food and Agricultural Science. http://nfrec.ifas.ufl.edu/contact/PatMinogue.shtml PARTICIPANTS: (1) Individuals: PI Patrick Minogue, PD Masato Miwa, Co-PD Anna Osiecka, Colaborators - Cheryl Mackowiak, Jeffrey Vowell, Roy Lima; (2) Partner organizations: Florida Dept. Environmental Protection, Florida Forest Service, Neil Land and Timber, Burch Family Farms; (3) Training: Daniela Chevasco, Ph.D. student, School of Natural Resources and Environment, The University of Florida. TARGET AUDIENCES: Pine straw producers (owners of forest land) are the primary target audience for this Research and Extension Program. These include forest industry, the Florida Forest Service, and non-industrial private forest landowners (NIPFL). The research being conducted will also build upon the scientific knowledge regarding fate of applied nutrients, effects of pine straw removal on nutrient cycling, and quantification of economic benefits and thresholds for fertilization in pine straw production. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Results from this study are supporting refinement of Florida Silviculture BMPs to protect groundwater quality. Nitrogen fertilization responses: This study showed that two consecutive annual applications of 128 lb DAP/ac (22 lb/ac N) increased surface soil NOx-N concentration without elevating NOx-N concentration of deeper soils (48-72 in depth), while two consecutive annual applications of 384 lb DAP/ac (67 lb/ac N) slightly increased deeper soil NOx-N concentration, and two consecutive annual applications of 641 lb DAP/ac (112 lb/ac N) significantly increased deeper soil NOx-N concentration, particularly after the second annual application. Since NOx-N is a relatively stable and mobile nutrient, any fertilizer rate that significantly increases NOx-N concentration below the primary rooting zone (generally the upper 48 inches) should be avoided to minimize groundwater N contamination. Nitrate leaching was more pronounced following the second fertilization in both studies. Rather than stipulating limits for a three-year period, BMPs should specify maximum annual amounts to apply, particularly since fertilizer applications in conventional silviculture are typically done every five to ten years. Annual fertilization guidelines would accommodate pine straw production, where annual fertilizations are common. This research suggests that two sequential annual applications of 112 lb N could be a threat to water quality in certain soils. While this level of fertilization is not widely practiced, it would be permissible under current BMPs. Fertilizer application guidelines are typically expressed in N equivalent weight. However, BMPs should address specific fertilizer forms, since the various forms applied undergo different transformations in the soil, affecting their availability for plant uptake, volatile losses and potential for leaching. New slow release fertilizers are being introduced for forestry, and research is needed to ascertain appropriate BMPs for their use. Phosphorus fertilization responses: Since DAP fertilizer application rates were determined to provide various N amounts up to the near maximum BMP limit of 250 lb/ac N in three years, two applications of the high DAP rate provided 120 lb/ac elemental P, which exceeded the BMP limit of 80 lb/ac elemental P in a three year period. Fertilization did not result in movement of P below the primary rooting zone or to groundwater in either study. Phosphorus is not a mobile nutrient, but P fertilization may increase soluble organic phosphorus (SOP), which is prone to leach. Continued monitoring for several years would be needed to ascertain the fate of applied P in this study. Pine growth responses: While the 2-year study period was too short to adequately evaluate tree growth and pine straw yield responses to fertilization, thus far these studies show that two consecutive annual applications of 384 lb DAP/ac significantly increased foliar and pine litter TKN content. Whereas, two consecutive applications of 128 lb DAP/ac were not sufficient to increase foliar and litter TKN content, and are likely below the threshold required to produce a growth response.

Publications

  • Minogue, P.J., M. Miwa, D.K. Lauer, and A. Osiecka. 2011. Preliminary results: Effectiveness of Silviculture Best Management Practices for Forest Fertilization in Pine Straw Production to Protect Water Quality in Florida. Institute of Food and Agricultural Sciences, Agricultural Experiment Station, North Florida Research and Education Center, Quincy, FL, Research Report 2011-02. 76 pp.
  • Osiecka, A., P.J. Minogue, and J.T. Wright. 2010. Effect of pine straw removal on pine straw yield and quality, wood volume, and nutrient budgets in fertilized loblolly pine (Pinus taeda), slash pine (Pinus elliottii) and longleaf pine (Pinus palustris) plantations in the Florida Sand Ridge Region. Institute of Food and Agricultural Sciences, Agricultural Experiment Station, North Florida Research and Education Center, Quincy, FL, Research Report 2010-02. 19 pp.


Progress 07/01/10 to 09/30/10

Outputs
OUTPUTS: Activities: (1) Two large-scale (12 acre) replicated studies were established in mid-rotation slash pine (Pinus elliottii L.) plantations in North Florida at locations with soils having contrasting leaching potential to evaluate and assess the effectiveness of current forest fertilization BMP's in reducing non-point source pollution for forest fertilization in pine straw production. (2) A a survey of 63 FL Division of Forestry County Foresters was completed to obtain general information regarding trends in fertilization for pine straw production, to ascertain educational needs, and also to obtain a list of significant pine straw producers (landowners)for a planned subsequent needs survey. Events: A six hour Pine Straw Production Workshop was conducted to disseminate information about sustainable management practices for pine straw production, including appropriate use of of forest fertilizers. PARTICIPANTS: (1)Individuals: PI Patrick Minogue, PD Masato Miwa, Co-PD Anna Osiecka, Colaborator: Cheryl Macowiak, (2) Partner Organizaions: Florida Dept. Environmental Protection, FL Division of Forestry, Neil Land and Timber, Burch Family Farms, (3) Training: Daniela Chevasco, Ph.D. student, School of Natural Resources and Environment, University of Florida TARGET AUDIENCES: Pine straw producers (owners of forest land) are the primary target audience for this research. These include forest industry, the Florida Division of Forestry, and non-industrial private forest landowners (NIPFL). The research will also build upon the scientific knowledge regarding fate of applied fertilizers in stands where straw is removed, thus interrupting nutrient cycling, which will be of interest to forest systems researchers worldwide. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
(1) This new study is providing cornerstone scientific information regarding nutrient fate for fertilization in pine straw production, which is widely practiced by growers who are likely to over-fertilize because of potential yield increases and economic incentives. (2) The 37 participants of our Pine Straw Production Workshop (representing 621,000 acres owned)were surveyed following the meeting and 100% indicated that they had learned something new, 66% said they would change behavior.

Publications

  • Osiecka, A. and P.J. Minogue. 2010. Developing herbicide prescriptions for forest vegetation management. Univ. of Florida Cooperative Extension Service Circular FOR125/FR. 11 pp. http://edis.ifas.ufl.edu/
  • Demers, C., A. Long, and P.J. Minogue. 2010. Longleaf pine regeneration. Univ. of Florida Cooperative Extension Service Circular SS-FOR-13/FR064. 9 pp. http://edis.ifas.ufl.edu/fr064
  • Minogue, P.J. 2010. Control understory vegetation to enhance pine straw yield. North Florida Research and Education Center Newsletter. September, 2010.