Investigating the Legume Green Fallow Alternative on North-Central Montana No-Till Operations

Project Overview

Project Type: Graduate Student
Funds awarded in 2010: $24,250.00
Projected End Date: 12/31/2010
Grant Recipient: Montana State University
Region: Western
State: Montana
Graduate Student:
Principal Investigator:
Dr. Perry Miller
Montana State University

Annual Reports


  • Agronomic: hay, wheat
  • Animals: bovine


  • Animal Production: feed/forage, winter forage
  • Crop Production: application rate management, conservation tillage, continuous cropping, fallow, no-till, nutrient cycling, organic fertilizers, tissue analysis
  • Education and Training: extension, on-farm/ranch research, participatory research
  • Farm Business Management: budgets/cost and returns, feasibility study
  • Natural Resources/Environment: biodiversity, soil stabilization
  • Production Systems: agroecosystems
  • Soil Management: green manures, nutrient mineralization, organic matter, soil analysis, soil quality/health
  • Sustainable Communities: sustainability measures

    Proposal abstract:

    Legume green fallowing (LGF) may help reduce dependence on inorganic Nitrogen (N) inputs and improve overall soil quality in agroecosystems, especially in dryland systems with high N demands and summer fallow practices. Northern great plains (NGP) dryland agriculture has historically rejected LGF because of reduced yields in subsequent crops from stored soil water depletion, but the recent innovations of early LGF termination and no-till practices that manage stored soil water more effectively may increase and reinvigorate LGF viability in this region. We are conducting an on-farm study working with six no-till wheat producers in north-central Montana utilizing LGF (green manures and/or forage crops) as a summer fallow alternative. This original study investigates LGF treatments under no-till management exclusively and early legume termination practices. Quantification of water use and N dynamics is needed, and will be assessed to inform adoption of this practice. Our on-farm aspect examines viability of LGF in a region where summer fallowing is still widely practiced, and where directly associated problems such as saline seepage and soil degradation are documented. Indications of reduced yield elimination in crops following LGF, increased N fertility independence for producers, and increases in overall soil quality via. soil N fertility over summer fallow are paramount goals of this project. If improved techniques of LGF management prove to be a viable practice in this region, adoption trends could prove to be instrumental in improving the agricultural sustainability of wheat commodity production in the dryland wheat-fallow regions of the NGP.

    Project objectives from proposal:

    1) Scientifically quantify the effects of LGF on soil N contributions, soil water use, and the effect they have on the following wheat crop compared to summer fallow. We are looking to see if patterns of N benefits emerge from legume-fixed N in both soil and/or the subsequent wheat crop, and to see if this crop is uncompromised by LGF water use compared to summer fallow. We will also seize any opportunities to compare the base green manure treatment to any forage harvest, cattle grazed, or pea-for-seed treatments of LGF offered by the producers involved.

    2) Assess how no-till management and early termination may affect LGF management. This objective will be illustrated if N dynamics and water use appear to be significantly different than the results of previous tillage-based LGF studies. Decreases in compromising soil water depletion by LGF will be especially informative to viability in the semi-arid NGP region.

    3) Assess LGF management over regionally varied sites and management practices by different producers. LGF effects over varied circumstances will illustrate the sensitivity of this management strategy to these differing circumstances. The degree of sensitivity exhibited will help to indicate the degree and scale to which LGF can be effectively implemented. Objectives 1-3 will be conducted over the course of 2 growing seasons and will be analyzed both annually and ultimately in the months following completion of field data collection.

    4) Conduct a basic economic analysis of LGF management compared to standard summer fallow under no-till management. We are looking for economic benefits of adopting LGF compared to summer fallow, such as N credits from legume fixation to soil and subsequent wheat crop, and reduction in weed control costs from LGF canopy/mulching effects and crop diversification. This will be conducted throughout the study based on producer feedback.

    5) Assess producer initiative to continue LGF management based on results of the study. Data indicating grain yield or quality increases from LGF management, or decreases in operating costs from a LGF management option provide immediate incentives to continue LGF management. Soil N fertility or observed soil quality increases may provide provide initiative to continue LGF for future benefits. An ultimate measurement of this objective will be incidence of producers involved choosing to continue and/or expand LGF management on their operations. This assessment
    will be conducted at post-study final producer interviews.

    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.