Using cover crop mixtures to improve soil health in low rainfall areas of the northern plains

Project Overview

Project Type: Research and Education
Funds awarded in 2011: $354,405.00
Projected End Date: 12/31/2015
Region: Western
State: Montana
Principal Investigator:
Dr. Perry Miller
Montana State University

Annual Reports

Information Products


  • Agronomic: wheat


  • Crop Production: cover crops, fallow, no-till, nutrient cycling
  • Education and Training: extension, on-farm/ranch research, participatory research
  • Soil Management: green manures, nutrient mineralization, soil microbiology, soil chemistry, organic matter, soil physics, soil quality/health

    Proposal abstract:

    Summer fallow has been used in dryland cropping systems to store water for subsequent crops, but the practice degrades soil quality. Our research tests the effects of a cover crop mixture (CCM) planted in the spring and terminated in June on crop yield, soil quality and water availability. We will compare the growth of single functional group cover crops with mixtures of up to eight species, including four plant functional groups. Functional groups will be selected that address soil quality issues specific to farming in the northern Great Plains, including: 1) species that fix N, to reduce N fertilizer inputs; 2) species which provide ground cover, to reduce weed establishment and minimize evaporation; 3) species with deep tap roots, to minimize compaction; 4) species with fibrous and extensive root systems, to add C to soil profile. Soil quality will be assessed with measures of soil nutrients and mineralization rates, characterization of the microbial community and mycorrhizal fungi, and physical parameters including measures of compaction. A field-scale study will be conducted on six farms, and a more complex plot-scale study will be done on four farms. With this research, we will provide relevant information on plant functional groups for farmer consideration when designing CCM seed mixtures. We will survey farmers in the first and third years to assess the effects of this project on knowledge and use of CCMs. If our results warrant it, there is the potential for adoption of NRCS-sponsored soil conservation incentives requiring a minimum number of functional groups be present within a CCM seed mix. Our results will be disseminated with a wide array of strategies including field days, workshops with presentations by both farmers and researchers, documents, radio, streaming video and grain grower newsletters.

    Project objectives from proposal:

    1. Position this project for maximal success by gaining familiarity with growth characteristics of targeted candidate species for CCMs by growing crops locally in 2011 prior to potential award of this grant.

    1a. We will produce seed of 8 - 12 crop species at Bozeman to gain greater familiarity with plant growth habit and obtain seed of known quality for research project.

    1b. To ensure success of our field research, we will monitor nearby farm fields of CCMs, as time and budget permits, to gain familiarity with sampling CCMs and with practical field challenges.

    2. Quantify the effects of CCMs (compared with fallow) on grain yield, quality and economic return compared with fallow.

    2a. We will determine differences (with 90% confidence) in yield and quality of grain following each CCM compared to fallow for four plot studies and six field scale studies following the second year of the study.

    2b. Based on grain yield, quality, seed costs, equipment costs, NRCS payments, etc., we will determine if the net economic return is different among the treatments. Our performance target is to identify soil-building CCMs that produce similar or more profit in a CCM-wheat system than fallow-wheat, because otherwise adoption is relatively unlikely.

    3. Determine the effects of CCMs on soil quality using fallow as a control.

    3a. Soil quality indicators that we will measure include biological (potentially mineralizable N (PMN), microbial biomass, enzyme activities, mycorrhizal colonization levels and infectivity potential, and earthworm density), physical (wet aggregate stability, temperature, compaction) and chemical (available nitrogen and phosphorus).

    3b. Comparing CCMs with single functional groups to those with subsets or the entire set of functional groups, we will identify the functional group(s) that most contributed to any soil quality change detected.

    3c. Indicators that are different between each CCM and fallow after the third year of the study will be identified. Our performance target is to identify which CCMs most improve different aspects of soil quality, allowing farmers to customize a CCM depending on their soil needs.

    4. Introduce growers and agricultural professionals (“audience”) to the potential sustainable aspects of CCMs.

    4a. We will conduct one Field Day and two workshops during the first year of the project, focusing on general CC principles and any regional research results (for example from ND). Our first performance target is to directly reach 200 people with these events, and indirectly reach another 800 by asking our audience to take handouts to neighbors, friends and colleagues and by producing a video of the Field Days that will be accessed online.

    4b. Our second performance objective will be to increase the audience's awareness and understanding of potential benefits of CCMs. We will assess this with audience evaluations.

    5. Educate audience about effects of CCMs on subsequent crop and economics.

    5a. In the winter after the wheat phase of this study, we will conduct three to four more workshops to share yield, quality and economic results, have one radio interview with a PI and produce a CCM webpage to share our findings. Our first performance target is to directly reach 300 people with these events and reach another 2,000 indirectly.

    5b. Our second performance target will be to increase our audience’s understanding of the agronomic and economic effects of CCMs in our region. This will be assessed with evaluations.

    6. Educate audience about the effects of CCMs on soil quality, including functional group benefits, based on our study.

    6a. In the year of the second CCM crop, we will host another Field Day, conduct two to three more workshops to discuss our soil quality results and prepare an extension fact sheet on our findings. Our first performance target will be to directly reach 300 people with these events and 1,200 indirectly.

    6b. Our second performance target will be to increase the understanding of plant functional groups and to assess this with our educational evaluation plan.

    7. Enhance adoption, if study results warrant, of CCMs.

    7a. Our performance target is to double the acreage of CCMs seeded in each study year in both MT and WY.

    7b. Recognizing the adoption lag that is typical for most agricultural systems research, we will work with the USDA Farm Service Agency to track adoption via affidavit-based reported MT and WY farm acres of CCMs until 10 years after this research has been completed.

    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.