Weeds, Nitrogen, and Yield: Measuring the Effectiveness of an Organic No-Till System

Project Overview

Project Type: Graduate Student
Funds awarded in 2013: $10,927.00
Projected End Date: 12/31/2015
Grant Recipient: Clemson University
Region: Southern
State: South Carolina
Graduate Student:
Major Professor:
Dr. Geoff Zehnder
Clemson University

Annual Reports


  • Vegetables: cucurbits, tomatoes


  • Crop Production: application rate management, conservation tillage, cover crops, no-till, organic fertilizers, tissue analysis
  • Production Systems: general crop production
  • Soil Management: organic matter, soil analysis

    Proposal abstract:

    Weeds are one of the biggest production hindrances in organic agriculture. Unlike conventional producers who rely on chemical herbicide sprays, herbicide-coated seeds, and genetically modified plants, organic growers must use a control regimen consisting of manual and mechanical weeding. Mechanical weeding or tilling the soil to eradicate weeds is effective but costly to the soil. No-till agriculture, which diminishes or eliminates tillage and instead relies on a dense, high-biomass stand of terminated cover crop to suppress weeds conserves both soil and off-farm nutrient inputs and thus can be especially advantageous to organic farmers. The objective of our experiment is to assess two tillage treatments (no-till and conventional tillage) and three fertilization treatments for organic tomato and summer squash production. Data will be collected on cover crop dieback, cover crop biomass production, weed management inputs, soil nitrogen, crop yield, and system inputs over two years.

    Project objectives from proposal:

    The objectives of our experiment are: 1. To assess two tillage treatments (no-till and tilled) of a rye and crimson clover cover crop for organic tomato and summer squash production; 2. To determine the interactions between two tillage treatments and three fertilization treatments (no nitrogen fertilizer, half the recommended rate of nitrogen fertilizer, and full recommended rate of nitrogen fertilizer) as they correspond to tomato and squash yields; and 3. To evaluate the management costs of a no-till system compared to that of a tilled system.
    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.