Optimizing spring cover crop management for productivity, soil health and climate resilience

Project Overview

Project Type: Research Only
Funds awarded in 2023: $249,267.00
Projected End Date: 11/30/2026
Grant Recipient: University of Maryland
Region: Northeast
State: Maryland
Project Leader:
Dr. Ray Weil
University of Maryland


  • Agronomic: barley, clovers, corn, hemp, radish (oilseed, daikon, forage), soybeans, vetches, wheat
  • Vegetables: other, sweet corn


  • Crop Production: catch crops, conservation tillage, cover crops, crop rotation, intercropping, no-till, nutrient cycling, nutrient management, water management
  • Education and Training: demonstration, extension, farmer to farmer, mentoring, on-farm/ranch research, participatory research, technical assistance, workshop
  • Natural Resources/Environment: biodiversity, carbon sequestration, indicators, soil stabilization
  • Pest Management: smother crops, weed ecology
  • Production Systems: agroecosystems, organic agriculture
  • Soil Management: green manures, nutrient mineralization, organic matter, soil analysis, soil physics, soil quality/health

    Proposal abstract:

    Cover cropping is a soil health best management practice, but <10% of US farms and <15% of Northeast farms regularly use cover crops (CCs) and fewer manage CCs to maximize benefits for farmers and society. A key question is when to terminate CCs in spring, either mechanically or with herbicides. Farmers typically terminate CCs when small and “easy to deal with.” Delayed termination allows CCs to grow longer and may triple biomass produced, therefore greatly increasing such benefits as erosion control, weed suppression, nutrient cycling, nitrogen fixation, compaction alleviation, and summer water conservation. Farmers who use CCs are increasingly interested in facilitating late CC termination by “planting green” (PG), a practice where a cash crop is no-till planted into a living green CC with termination performed either simultaneously or a week or two later.

    Increasing climate change concerns have stimulated emerging markets that pay farmers to sequester carbon in soils. Current models have little-to-no basis for estimating carbon in CC roots. Data are urgently needed on how CC termination timing affects root carbon contributions, which are more than shoot contributions for sequestration. Another issue lacking data is farmer concern that CCs may increase slug problems. Finally, farmers need data on how termination timing affects weeds and soil moisture.  We hypothesize that 1) shoot/root ratios are not constant over time and PG may optimize both root and shoot carbon sequestration;  2) green CCs coexisting with cash crop seedlings may distract slugs and reduce cash crop damage; 3) planting green may optimize weed suppression and summer water conservation.

    We will conduct experiments on research stations with coarse and fine textured soils, and on four to six collaborating farms. The station experiments will test three termination timings relative to cash crop planting (three-four weeks prior; simultaneously with; one-two weeks after) and three CC types (no-cover control; grass-legume or grass-brassica-legume mixture; and pure winter cereal). Collaborating farms will use 3-4 treatments (farmer’s choice) per farm. Farmers will conduct all operations and measure yields while researchers will collect data on shoot/root biomass, slug damage, crop stands, seed placement, datalogger-sensed soil moisture and temperature, weed biomass and residue cover at canopy closure, and shoot nutrient content.

    Researchers and farmers will keep detailed notes on planter settings, operational issues such as CC wrapping, seed placement, slot closing, and machine wear. Lessons-learned will be promulgated through extension efforts to reduce risk barriers for farmers wanting to grow more effective CCs more beneficial for their farm and ecosystem services. Farmers help design the research and those with PG experience will mentor other farmers wanting to try PG. An advisory board will guide the direction of the project, which will strive to include a range of farm types and sizes.

    Project objectives from proposal:

    Research to optimize spring cover crop management with a focus on comparing termination methods and termination timing (from several weeks before to several weeks after cash crop planting). We will learn how these practices affect root and shoot carbon contributions, soil moisture use and conservation, weed and slug pressure, soil health functions, farmer costs and crop yields. Our results will reach 100s of farmers who are on-the-fence about cover crops or use them in ways that provide little benefit, and provide the confidence and information they need to adopt cover cropping with late termination practices that maximize cover crop benefits.

    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.