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United States Department of Agriculture

Agricultural Research Service

Research Project: Effect of Cover Crops, Soil Amendments, and Reduced Tillage on Carbon Sequestration and Soil Health in a Long-Term Organic Vegetable System
2013 Annual Report


1a.Objectives (from AD-416):
1. Encourage organic transition by developing organic vegetable cropping systems that improve carbon sequestration and soil health through cover crops, composting, and reduced tillage.

2. Enhance ecosystem services on organic farms by increasing biological management leading to suppression of pests (weeds, pest insects, nematodes, diseases) in cover crop-intensive systems.

3. Develop recommendations for methods to improve soil quality on organic farms based on results derived from horticultural and soil data and simulation models:

a. Develop nitrogen and carbon budgets; b. Develop relationships between individual/integrative indicators of soil quality and environmental/productivity endpoints; and c. Calibrate and validate the EU-ROTATE_N model for organic horticultural cropping systems in Iowa and Florida.

4. Determine how product quality and shelf life are affected by different management practices in organic systems and identify linkages between soil properties, crop health, and postharvest quality.


1b.Approach (from AD-416):
This project is driven by two broad research hypotheses. They will be tested using a comprehensive approach including the collaboration of researchers and growers over two distinct environmental conditions.

Hypothesis 1: Organic vegetable systems with integrated management strategies, including composted animal manure, cover crops, and reduced tillage, will lead to increased C sequestration, improved soil quality and crop health, and greater economic viability, by reducing production costs and increasing carbon sequestration rates for potential economic value.

Hypothesis 2: Different management practices within organic or conventional systems, fundamentally linked to soil conditions and crop health, will exhibit differential effects on postharvest quality attributes of vegetables. Research will begin in 2011 on University Experiment Station sites in Iowa and Florida, and on grower-cooperator fields in each state. An equivalent experiment will be established in each state to investigate the effect of different vegetable cropping systems on carbon sequestration, soil quality, environmental quality endpoints, crop health, weed, insect pest and nematode populations, yield, food quality attributes of crops, and economic performance. The experiment will evaluate three-year vegetable cropping rotations consisting of tomato(spring)-lettuce(fall)-yellow squash(spring)-broccoli(fall)-onions(spring)-beans(fall). Treatment combinations will evaluate the effect of reduced tillage, black plastic mulch, fall-planted cover crops, and animal manure compost on agroecosystem parameters.


3.Progress Report:

A rye/hairy vetch cover crop planted last week of September 2012. Lysimeter water nitrate and soil carbon dioxide (CO2) flux data collection stopped for the 2012 growing season on October 30, 2012. Lysimeter water nitrate data collection began for the 2013 growing season on April 8, 2013. Soil CO2 flux data collection began for the 2013 growing season on April 22, 2013. (No CO2 flux data collected between June 30 and July 8, 2013.) Above-ground cover crop biomass samples collected on May 30, 2013, prior to tilling (June 8, 2013) or roller/crimping (June 19, 2013) to kill cover crops. Tomatoes transplanted and sweet corn planted June 26-27, 2013. Analysis of soil, plant, and water samples is in progress.


Last Modified: 8/30/2014
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