Deep soil nitrogen: A resource for sustainability in the mid-Atlantic using early cover crops

Project Overview

Project Type: Research and Education
Funds awarded in 2014: $249,576.00
Projected End Date: 10/31/2018
Grant Recipient: University of Maryland
Region: Northeast
State: Maryland
Project Leader:
Dr. Ray Weil
University of Maryland
Dr. Sarah Hirsh
University of Maryland

Annual Reports

Information Products


Not commodity specific


  • Crop Production: cover crops, nutrient cycling, application rate management
  • Education and Training: extension, on-farm/ranch research
  • Soil Management: soil quality/health

    Proposal abstract:

    Covercrops are among the most cost-effective approaches to reduce nitrate leaching from cropland, and yet, traditional covercropping captures and releases N ineffectively. In Maryland subsidized covercrops are credited with only 8lbs/acres N load reduction and no fertilizer savings or yield boost. This may explain why covercrop adoption is still low. Despite subsidies up to $105/A, less than half of MD cropland is covercropped, whereas in non-subsidy states estimates suggest only about 5% of farmers and 1% of cropland have covercrops. There is now evidence that some early planted covercrops are able to absorb sub-soil N effectively and release it so that large amounts of N can be taken up by the following crop. This could reduce N leaching losses and N-fertilizer applications to summer crops and hence make covercrops more environmentally beneficial and economically attractive. Covercrop adoption would increase and be less reliant on subsidies. We’ll engage MD-DE-PA farmers in a comprehensive research and education program designed to convert the just described situation from lose-lose into win-win developing and promoting early deep-rooted covercrop systems that help farmers profit from N already on-farm while addressing environmental impacts and regulatory pressures. We predict that new covercrop practices can pay $50–500/acre by 1) capturing 100-200 lbsN/acre in fall, 2) increasing yields, 3) releasing N in spring to reduce fertilizer use, while at the same time meeting regulatory requirements to substantially reduce water quality impacts. Education approaches, research treatments, covercropping windows and specific benefits will vary by farm type. In PA and central MD we’ll focus on dairy farmers growing corn silage; in Eastern Md we’ll focus on grain and vegetable farmers (especially those using poultry manure). Vegetable farms may realize the greatest benefits despite limited acreage. The project will utilize deep soil N by getting rapid-growing deep-rooted non-immobilizing covercrops established early. This will involve using early-maturing crop cultivars, changing crop rotations, using aerial seeding (possibly with seed coatings or irrigation) into standing crops or interseeding into young crops, and assuring sufficient startup nutrients. Farmer and research station field days, winter workshops, an interactive website, video webinars, and a range of farmer-guided on-farm research and demonstrations will be employed with messages gaining specificity as our research clarifies deep-N and how to use it.

    Performance targets from proposal:

    250 farmers plant 25,000 acres early radish/rye covercrops reducing N leaching by 2,000,000 Lbs; 100 of them also reduce N application by 50 lbs. on 10,000 acres, saving $0.5 million annually. 20 advisers recommend early covercrops and 2 state Agriculture Departments include them in their N load reduction programs.

    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.