Cover crop mulches for no-till organic onion production

Cover crop mulches for no-till organic onion production

Summary

The purpose of this project is to expand the knowledge base informing sustainable agricultural practices. This project addresses three key challenges for organic, reduced-tillage vegetable production. First, selecting summer cover crops that winter kill eliminates the challenge of mechanically killing the cover crop. Second, we are evaluating quantity and timing of nitrogen release from both the cover crops and organic amendment nitrogen during over-wintered vegetable production. Third, we are evaluating the weed control potential of the different cover crop residues. This is a systems-level experiment that will demonstrate the interactions of many aspects of sustainable vegetable production in the southeast.

Objectives/Performance Targets

1. Evaluate monocultures and mixtures of summer cover crops appropriate for conservation tillage in organic fall planted vegetable production systems as a way to reduce soil erosion and agrochemical use.
2. Evaluate rates of soybean meal in combination with cover crop mixtures for optimum nitrogen management in over-wintering onions.
3. Evaluate onion growth and development under cover crop conservation tillage systems.

Accomplishments/Milestones

To date the first year of this trial was completed in May 2007 and the second year will conclude with onion harvest in May 2008. The following data collection was conducted during the first year and is currently being replicated: Soil sampling to determine mineral nitrogen at two depths for all treatment plots was conducted at three different times relative to onion transplanting: pre-plant (Oct. ‘06), bulb initiation (March ‘07), post harvest (May ‘07). The split treatment of broadcast applied soybean meal was monitored every two weeks with soil sampling two depths. Weed density, percent cover, species composition and weeding-times was evaluated twice during onion growth. Onion harvest was taken from 30 row feet of the weeded section and 6 row feet of the un-weeded section of each plot. Onions were graded, counted and weighed. Onion mortality, rate of bolting and bulb nitrogen content was also determined.

Impacts and Contributions/Outcomes

Preliminary findings were presented to growers at a Seasons of Sustainable Agriculture workshop at the Center for Environmental Farming Systems in Goldsboro, NC on May 10, 2007. Results of the first field season were shared as part of a session at the 22nd Annual Sustainable Agriculture Conference in Durham, NC on November 10 2007.
We provided producers with specific information about summer cover crop selection and rotation strategies as well as examples of the weed pressure and availability of organic amendment nitrogen during the winter growing season following grass or leguminous cover crops.

Collaborators: