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United States Department of Agriculture

Agricultural Research Service

Research Project: Strategies to Improve Soil and Pest Management in Organic Vegetable Production Systems

Location: Crop Improvement and Protection Research

2009 Annual Report

1a. Objectives (from AD-416)
Objective 1 Develop ecologically-based soil and pest management strategies that enhance soil quality, nutrient cycling, and profitability, and reduce off-farm inputs in high-value, organic vegetable production systems. Sub-objective 1.A. Evaluate the effects of cover cropping frequency and compost application on soil quality, vegetable yield and quality, and system profitability. Sub-objective 1.B. Evaluate the effects of a legume-rye mix versus non-legume cover crops on vegetable yield. Sub-objective 1.C. Evaluate the effects cover crop seeding rates on weed density and weed management costs in subsequent vegetable crops grown in rotation sequences. Objective 2 Evaluate the energy efficiency, costs, and effectiveness of standard and alternative technologies and strategies for managing cover crop residue in high-value organic vegetable production. Sub-objective 2.A. Compare fuel use, labor costs, and agronomic effectiveness of cover crop residue incorporation with standard primary tillage implements (disc-and-chisel) versus with an alternative implement (spader). Sub-objective 2.B. Evaluate the roller-crimper implement for killing cover crops on beds for no-tillage organic vegetable production.

1b. Approach (from AD-416)
Organic production is increasing in the U.S., a response in part to public concerns about agricultural sustainability, food safety, & environmental quality. While farmers may consider moving to an organic system, continuity of economic viability during the transition from conventional to organic farming systems is a serious challenge. There is little scientific, organic-based information for farmers as they choose among the options available for the build-up of soil organic matter, maintenance of soil fertility, crops and cultivars, and disease and insect pest management practices. Improved understanding of the processes that occur during the transition to mature organic production systems is necessary to ensure the economic success of organic farming systems. Replacing 5305-21620-011-00D (9.08).

3. Progress Report
Research in organic systems is severely lacking despite the recent growth of the organic market. The research in this project occurs on certified organic land at the ARS and on collaborating farms and includes short-term component research and long-term systems research. The research during the past year focused on crop rotations, soil fertility management, weed management, and cover cropping in high-value organic vegetable systems. Preliminary trials were also conducted to evaluate an implement called a roller/crimper for mechanically killing cover crops on beds used for vegetable production. The research is applicable to small, medium and large-scale organic farms, and to conventional farms that are shifting to more sustainable soil management practices. This research involves collaboration on multidisciplinary projects with scientific and extension personnel from other agencies. The sixth year of the long-term, multidisciplinary experiment with eight different organic systems for high-value organic vegetable production was completed in FY 2009. This ongoing study is the major focus of this project and is the longest running systems study in California on high-value organic vegetable production systems. Data were collected on cover crop yield, weed biomass, vegetable production, weed densities, soil quality and profitability. These data demonstrated the importance of high seeding rates for a legume-rye cover crop to maximize weed suppression in subsequent vegetables, and revealed that frequent cover cropping is much more important than compost application for maintaining vegetable yields and improving soil quality.

4. Accomplishments
1. Novel cover crop mixtures of legumes and cereals. Cover crop mixtures of legumes and cereals combine the scavenging abilities of cereals with the nitrogen fixing ability of the legumes. Such mixes can reduce losses of nitrogen to ground and surface water, and reduce the need for expensive supplemental nitrogen fertilizers. Novel mixtures of legumes and cereals were evaluated by ARS scientist in Salinas, CA for biomass production, nitrogen content and weed suppression in on-farm trials in Salinas and Hollister, California over several years. This research provides farmers with critical information that will help them choose more cost effective cover crop mixtures, and improve weed and soil fertility management in vegetable rotations.

Review Publications
Boyd, N.S., Brennan, E.B., Smith, R., Tokota, R. 2009. Effect of Seeding Rate and Planting Arrangement on Rye Cover Crop and Weed Growth. Agronomy Journal 101:47-51.

Brennan, E.B., Boyd, N.S., Smith, R., Foster, P. 2009. Seeding Rate and Planting Arrangement Effects on a Legume-Oat Cover Crop in Organic Vegetable Systems. Agronomy Journal. 101:979-988.

Last Modified: 06/22/2017
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