By Heather Darby and Lindsey Ruhl et.al
Cover crops can offer many benefits, including improved soil health, weed suppression, and erosion control. They can also contribute nitrogen to cash crops, reduce the need for herbicides, and conserve soil moisture. These benefits can contribute to higher yield and quality of cash crops. However, a cover crop’s biomass (quantity of plant material) and growth stage impact these benefits.
In the UVM Extension Northwest Crops and Soils Program (NWCS) 2024 report “Impact of Cover Crop Termination Timing on Grain Corn Productivity,” we describe our research to assess the impact of cover crop termination timing on weed biomass, corn seedling populations, vigor, pest damage, and grain corn yield. From 2020 through 2022 at Borderview Research Farm in Alburgh, VT, we assessed four cover crop management practices:
- no cover crop (Bare),
- planting Brown (cover crop terminated 3 to 4 weeks before corn planting),
- planting Green/Brown (cover crop terminated 2 to 8 days before corn planting), and
- planting Green (cover crop terminated 3 to 5 days after corn planting).
The study was one of 16 conducted in the Northeast, Midwest, and South, coordinated by the Precision Sustainable Agriculture, a national network funded by the USDA’s National Institute of Food and Agriculture from 2019 to 2025.
The full NWCS report on the Vermont study is 10 pages long, so we thought this short summary might be helpful to grain corn growers during planting season.
The Research Design
The soil type at the research site was a Covington silty clay loam with a 0-3% slope. We planted winter rye (var. AC Hazlet) at 70 lbs ac-1 at the end of September or early October each year and measured its biomass just prior to termination with a glyphosate herbicide. We terminated Brown cover crop treatments at the end of April, Green/Brown cover crop treatments in mid-May, and Green cover crop treatments at the end of May. In each plot, we assessed corn seedling populations and vigor when corn was in the third leaf stage (V3) and weed biomass when corn was in the fifth leaf stage (V5).
Source : uvm.edu