Source: UNIV OF HAWAII submitted to
AN ECOSYSTEM APPROACH TO RESTORING AND CONSERVING SOIL QUALITY IN DEGRADED LANDS IN THE PACIFIC ISLANDS
Sponsoring Institution
State Agricultural Experiment Station
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0194120
Grant No.
(N/A)
Project No.
HAW00123-1012S
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2002
Project End Date
Sep 30, 2005
Grant Year
(N/A)
Project Director
El-Swaify, S. A.
Recipient Organization
UNIV OF HAWAII
3190 MAILE WAY
HONOLULU,HI 96822
Performing Department
NATURAL RESOURCES & ENVIRONMENTAL MANAGEMENT
Non Technical Summary
Erosion degrades soil quality and promotes sediment-based pollution in Hawaii and the tropics. We will quantify the benefits of residue recycling and conservation tillage for enhancing soil quality and controlling sediment movement from Oxisols
Animal Health Component
55%
Research Effort Categories
Basic
15%
Applied
55%
Developmental
30%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1040199201040%
1045210201010%
1110199201010%
1330199201020%
1332410201010%
1335210201010%
Goals / Objectives
1) Evaluate the effectiveness of alternative tillage methods and organic residue management options for controlling soil erosion and rehabilitating highly eroded tropical soils. 2) Determine the potential benefits of conservation tillage, live ground cover, and organic matter incorporation on physical, chemical, and biological soil qualities.
Project Methods
This is part of a joint project with the University of Guam College of Agriculture. The Hawaii studies under this project will be conducted on the Oxisol of the CTAHR Poamoho Experiment Station in central Oahu. The soil is a highly weathered Tropeptic Haplustox, and the site has been used in earlier studies to quantify erosion effects on soil productivity. Previously imposed erosion levels ranged from zero to 35 cm (El-Swaify, 2001, Journal of Communications in Soil Science and Plant Analysis: 187-1201). Selective replicated field and greenhouse studies will be made to determine or simulate the effects of tillage type and intensity, source and quantity of organic amendments, and methods of applying these amendments.

Progress 10/01/02 to 09/30/05

Outputs
Work on this grant continues under a different project number for which a progress report is provided separately. This phase used greenhouse simulation for rehabilitating eroded Oxisols. Physical soil quality factors were reflected by compaction as measured by bulk density; chemical/nutrient quality factors were reflected by available N, and biological factors were reflected by enrichment in organic amendments. Corn plants were monitored by weekly measurements of plant heights. In this first phase, the dry yields of the corn shoots were not significantly affected by soil bulk density but there was a highly significant difference between the applied nitrogen levels and in response to organic amendments. Yields in amended soils were dramatically increased with nitrogen supplement, except for chicken manure because this material is already highly enriched in nitrogen.

Impacts
Eroded tropical soils possess severe constraints that affect their productivity and contribution to the health of the environment. Restoring productivity and quality to these soils, therefore, requires improvements in soil chemical, physical and biological properties. In this phase of the project, a combination of physical manipulation by appropriate tillage, nutrient restoration by fertilization, and biological enhancement by organic amendments offer a promising strategy for integrated management of soil quality restoration in eroded soils.

Publications

  • No publications reported this period


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

Outputs
Greenhouse simulation of eroded Oxisol rehabilitation continued. Physical soil quality factors were reflected by compaction as measured by bulk density. Densities of 1.0 and 1.3 Mg/m3 were used. Chemical/nutrient quality factors were reflected by available N (0, 0.5 and 1.0%). Biological factors were reflected by enrichment in organic admendments, namely peat moss, redwood, and chicken manure added at levels of 10%, 25% by volume. Leachates were collected weekly and analyzed for nutrient content. The plants were monitored by weekly measurements of plant heights. In the first experiment, the dry yields of the corn shoots were not significantly affected by soil bulk density. In contrast, there was a highly significant difference between the two nitrogen levels and in response to organic amendments. Yields in amended soils were dramatically increased with nitrogen supplement, except for chicken manure because this material is already highly enriched in nitrogen.

Impacts
Eroded tropical soils possess severe constraints that affect their productivity and contribution to the health of the environment. Restoring productivity and quality to these soils, therefore, requires improvements in soil chemical, physical and biological properties. In this phase of the project, a combination of physical manipulation by appropriate tillage, nutrient restoration by fertilization, and biological enhancement by organic amendments seem to be a promising strategy.

Publications

  • No publications reported this period


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

Outputs
The experiments on greenhouse simulation of eroded Oxisol rehabilitation continued. Pioneer Hybrid 1035 field corn is used as an indicator crop. Soil bulk densities of 1.0 and 1.3 Mg/m3 were used to evaluate root penetration resistance in 2 Kg containers. Two levels of supplemental nitrogen (0, 1.8 g per pot) were compared in the presence of three types of organic additives (peat moss, redwood, and chicken manure). The latter were added at levels of 10%, 25% by volume. Thus, there are total of 28 treatments including controls, and each treatment has 3 replications. To ensure that soil quality indicators include the soils ability to regulate water quality, plastic leachate collectors were installed in each soil container. Leachates were collected weekly and analyzed for nutrient content. The plants were monitored closely with weekly measurements of plant heights. The first experiment was concluded at the end of the 5th week after planting. Based on the dry yields of the corn shoots, we found no significant difference between the two bulk densities. However, there was a highly significant difference between the two nitrogen levels. Yield benefits of organic amendments were dramatically increased with nitrogen supplement. The exception was chicken manure for which dry yields decreased after nitrogen was added. This is explained by the fact that this material is already highly enriched in nitrogen. Overall, the two best yields were obtained with 10% of peat moss with nitrogen and chicken manure without nitrogen added.

Impacts
Eroded tropical soils possess severe constraints that affect their productivity and contribution to the health of the environment. Restoring productivity and quality to these soils, therefore, requires improvements in soil chemical, physical and biological properties. In this early phase of the project, a combination of physical manipulation by appropriate tillage, nutrient restoration by fertilization, and biological enhancement by organic amendments seem to be a promising strategy.

Publications

  • No publications reported this period


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

Outputs
No progress to report. This project was initiated on October 1, 2002.

Impacts
(N/A)

Publications

  • No publications reported this period