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United States Department of Agriculture

Agricultural Research Service



2009 Annual Report

1a. Objectives (from AD-416)
(i) Estimate biomass production and nutrient reserve in leguminous cover crops, i.e. sunn hemp, and velvetbean, under an arid temperate vs. humid tropical climatic condition in vegetable production systems. (ii) Estimate mineralization rates of the above cover crops and carbon sequestration rates under the above agroclimatic vegetable production systems. (iii) Trace gas emissions and ammonia volatilization with different nutrient and residue management practices in a vegetable rotation system. (iv) Estimate nutrient transformation, trace gas emissions, and carbon sequestration during decomposition and residue turnover from biofuel coproducts and other agricultural wastes.

1b. Approach (from AD-416)
Field studies will be conducted in Columbia Basin irrigated production region in WA (arid, temperate) and near Homestead, FL (humid, subtropical). Sunn hemp and velvetbean cover crops will be grown following the standard production practices for each of the above production regions. Total biomass production and nutrient reserves in each of the cover crops will be estimated. Following the incorporation of the cover crops, the decomposition of the residue, rate of mineralization, and carbon sequestration rate will be estimated. Trace gas emissions and ammonia volatilization will be evaluated under different fertilizers and residue management for potatoes, including fertigation, controlled resease fertilizer, and during decomposition and mineralization of organic amendments including biofuel coproducts and animal manures. Formerly 5354-21660-001-06S (10/08).

3. Progress Report
The main objectives were to test different cover crops in various agroclimatic zones for their efficacy in sequestering carbon in order to reduce the release of carbon dioxide. Results of these studies have shown that legume and non-legume mixture of cover crops can improve the quantity of biomass accumulated. Sorghum sudangrass plus sunn hemp cover crops had the greatest quanity of biomass associated with high amount of nitrogen (N) accumulated in the plant tissue. Legume cover crop had faster mineralization rate and contributed more N to the soil than did the non-legume cover crops. This research provides sound information to local growers for cover crop species selection and management to obtain the optimum amount of biomass for carbon sequestration and improved soil quality. This project was monitored via emails and phone calls between ADODR and project leader.

4. Accomplishments

Last Modified: 10/20/2017
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