Understanding the Influence of Soil Microbial Diversity on the Synchronization of Cover Crop Residue Nitrogen Mineralization at Critical Growth Stages of Corn and Soybean Cash Crops

Project Overview

Project Type: Graduate Student
Funds awarded in 2016: $11,154.00
Projected End Date: 12/31/2017
Grant Recipient: Purdue University
Region: North Central
State: Indiana
Graduate Student:
Faculty Advisor:
Dr. Shalamar Armstrong
Purdue University


  • Agronomic: corn


  • Crop Production: conservation tillage, cover crops, no-till
  • Production Systems: agroecosystems
  • Soil Management: nutrient mineralization, soil microbiology, soil quality/health

    Proposal abstract:

    Cover crop adoption in the Upper Mississippi Basin has increased by 212% over the last 5 years andfarmers have a working understanding of how cover crops can be used as tool to increase soil healthand reduce nitrate loading from tile-drained fields to surface waters. However, little is understoodabout how the inclusion of cover crops influence the soil microbial community and their efficiency infacilitating N release from cover crop residue. Therefore, the proposed objectives of this study are toi.) determine the impact of cover crop species and mixtures on the release of N following cover croptermination within different cropping systems, ii.) evaluate the impact of cover crop species andmixtures on the soil microbial community diversity, as it relates to N mineralization amongtreatments, and iii.) establish a correlation between cover crop residue N release and critical growthstages of corn and soybean crops. The research treatments were established in 2015, thus our analysiswill consist of a two year effect. Systematic soil and plant sampling occurring post cover croptermination during the spring and summer will detect changes in soil inorganic N concentrations andthe facilitating soil microbial community over time. Data generated from this study could lead to abetter understanding of the timing of cover crop residue N release and the diversity of the facilitatingsoil microbial community. Results from this study could advance the understanding of how N releasefrom cover crop residue, which could reduce the potential of yield loss due to N immobilizationfollowing cover crop termination, as well as the confusion linked to cover crop selection and thetiming of cash crop planting following cover crop termination for North Central SARE farmers.

    Project objectives from proposal:

    The overarching goal of this study is to develop a comprehensive understanding of how cover crop
    species and soil microbial community diversity influence the availability of soil inorganic nitrogen to
    cash crops following cover crop termination.
    Although cover crop adoption has increased rapidly within the North Central Corn Belt Region, there
    is still hesitation among famers regarding the implementation of cover crops. Thus, only a minute
    portion of acres (~1.7%), relative to total cultivated acres, are cover cropped, and only ~3.3% of
    cover crop adapters use cover crops on all farm land. The hesitation is believed to be linked to a lack
    of knowledge of how cover crops affect N availability for subsequent cash crops, which significantly
    influences yield and profit. Many farmers understand that cover crop adoption results in increased
    soil health measures; however, farmers don’t understand when cover crop residue N will be available
    to the subsequent cash crops and how that affects their current N management systems. Thus, the
    learning outcomes of this study are to develop knowledge on the timing of N release from the residue
    of different cover crop species within a corn-soybean rotation, to develop an understanding of how
    the diversity of the soil microbial community affects the efficiency of cover crop residue N release,
    and to establish a correlation between cover crop residue N release and critical growth stages and N
    demand of corn and soybeans. Accomplishing our learning outcomes could lead to the educating of
    farmers, the NCRS, conservation agents, and trainers on how different cover crops species affect N
    availability. This will increase their knowledge on cover crop selection and how N management plans
    could be adjusted based upon the N release pattern of cover crop selection.

    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.