Cover crop mulches for no-till organic onion production

Project Overview

Project Type: Graduate Student
Funds awarded in 2007: $10,000.00
Projected End Date: 12/31/2008
Grant Recipient: North Carolina State University
Region: Southern
State: North Carolina
Graduate Student:
Major Professor:
Dr. Nancy Creamer
North Carolina State University

Annual Reports


  • Agronomic: millet
  • Vegetables: onions


  • Crop Production: conservation tillage
  • Farm Business Management: whole farm planning
  • Pest Management: flame, mulches - killed, mulching - vegetative, physical control
  • Production Systems: holistic management
  • Soil Management: green manures, nutrient mineralization, soil analysis

    Proposal abstract:

    The environmental and sustainable production benefits of conservation tillage and cover cropping are well documented respectively. More research is needed to further integrate these practices into organic vegetable production systems. Key challenges for organic no-till include 1. Effective termination of cover crop 2. Coordinating quantity and timing of cover crop and amendment nitrogen release with subsequent crop demand 3. Weed management. In the southeastern US there is a potentially effective niche for summer annual cover crops that will frost-kill preceding a fall planted cash crop. We will evaluate the impact on weeds and crop yield by in-situ mulches of summer annual cover crops for fall planted organic onions. Cover crop treatments include foxtail millet (Setaria italica (L.) Beauv.), cowpea ‘Iron & Clay’ (Vigna unguiculata (L.) Walp.), three different mixtures approximating 70/30, 50/50, 30/70 ratios of percentage final biomass of millet/cowpea, and bare ground controls. Onion transplants will be no-till planted into the rolled cover crop residues. Soybean meal (SBM) will be assessed as an organic supplemental nitrogen source for onion growth. Cover crop treatments will be split for SBM application at zero, 1X and 2X rates. Soil mineral nitrogen will be assessed on a bi-weekly basis during onion growth (Nov. – June). Weed pressure will be evaluated at two weeding dates and at onion harvest. We hypothesize that grass/legume mixtures will be the most effective mulch for optimizing onion yield because they will be combining the benefits of the grass (maximum weed suppression) and the legume (maximum nitrogen contribution).

    Project objectives from proposal:

    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.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.