Effect of winter cover crops on soil nitrogen dynamics in no-till corn systems

Project Overview

Project Type: Graduate Student
Funds awarded in 2017: $14,998.00
Projected End Date: 08/31/2019
Grant Recipient: University of Maryland, College Park
Region: Northeast
State: Maryland
Graduate Student:
Faculty Advisor:
Dr. Katherine Tully
University of Maryland


  • Agronomic: barley, corn, rye, wheat


  • Crop Production: conservation tillage, cover crops, nutrient cycling, nutrient management
  • Production Systems: agroecosystems

    Proposal abstract:

    Cover crops play a critical role in nitrogen (N) management, both as N scavengers while growing and as N suppliers to the succeeding main crop while decomposing. Farmers are aware that grass cover crops can immobilize soil N and make it less available to the main crop. However, farmers often do not know how much N is being immobilized by their cover crops. Farmers, therefore, find it difficult to manage N for the succeeding main crop. Decision support tools are being developed to address this need; however, they often do not accurately predict N availability from surface-mulched residues. In this project, I propose to determine the impact of cover crops on soil N scavenging, soil N availability, yields, and improve the performance of an existing tool to predict N availability from surface residues in no-till corn (Zea mays L.) systems. This research will be conducted on 75-80 farms across the mid-Atlantic US as part of the larger project funded through the Natural Resources Conservation Service’s Conservation Innovation Grant. Farmers will provide strips of +/- cover crops going into a corn crop. The NE-SARE grant will fund only a subset of these experiments (15 farms) across Maryland and Pennsylvania. A controlled microcosm study will also be conducted as part of NE-SARE grant to improve decision support tool that farmers can use to manage N effectively in cover-crop based no-till corn systems. As a result, I anticipate an increase in cover crop adoption and tighter nutrient cycling in field corn production.

    Project objectives from proposal:

    The specific objectives of the proposed project are to:The specific objectives of the proposed project are to:

    (1) Assess the ability of cover crops to scavenge soil N. I hypothesize that soil N scavenging by cereal cover crops will be higher under conditions that favor high drainage (i.e. coarse-textured soils and high rainfall areas). 

    (2) Determine how cover crops affect N availability to the succeeding corn in no-till cropping systems. I hypothesize that the net effect of cover crops on soil N availability depends on cover crop species, growth stage, quality at termination, soil type, and climatic conditions during the corn phase. 

    (3) Determine the interactive effect of soil moisture and temperature on soil N availability from surface-applied cover crop residues. I hypothesize that soil N availability from surface-applied cover crop residue decomposition will increase with increasing soil moisture and temperature. 

    (4) Assess the effects of cover crops on no-till corn yields. I hypothesize that cover crops will have neutral or positive effects on no-till corn yields. 

    (5) Evaluate and improve the accuracy of the existing Cover Crop Nitrogen Calculator tool in predicting soil N availability from surface-mulched cover crop residues in no-till corn systems. I will use data from multi-farm experiments (Objective 2) to evaluate the accuracy of the calculator and improve it using data from controlled laboratory experiments (Objective 3).

    Objectives (1-2) and (4-5) are components of larger study design aimed at understanding the economic and environmental services of winter cover crops in the mid-Atlantic US (Maryland, Pennsylvania, North Carolina, South Carolina, and Georgia). These objectives will be better addressed by including as many farms as possible with wider soil types and climates. On-farm experiments will be conducted on at least 75-80 farms across the mid-Atlantic US; the majority of these on-farm experiments will be funded from the NRCS-CIG. The NE-SARE Graduate Student Grant will be used to cover part of the expenses in conducting on-farm experiments on 15 sites located at Maryland and Pennsylvania. Based on previous work from Dr. Mirsky’s lab, it is evident that the existing tools do not accurately predict soil N availability from surface residues due to great fluctuations in moisture and temperature [1]. Therefore, controlled microcosm studies (Objective 3) are needed to parameterize and improve the accuracy of existing tools for use in cover crop based no-till corn systems (Objective 4). I will explicitly use the NE-SARE Graduate Research Grant to conduct laboratory microcosm studies to answer Objective 3.

    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.