The Feasibility of Cover Crops in Dryland Cropping Systems in SW Colorado and SE Utah

View the project final report

• 2016 annual report

Commodities

Practices

• Crop Production: cover crops, crop rotation, fallow, nutrient cycling
• Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research, participatory research, workshop
• Farm Business Management: budgets/cost and returns, feasibility study
• Soil Management: green manures, organic matter, soil analysis, soil microbiology, soil quality/health
• Sustainable Communities: public participation

Our long-term goal is to enhance the sustainability of dryland cropping systems in SW Colorado and SE Utah by growing cover crops during the fallow period between two cash crops. Our objectives are to: 1) evaluate the performance of several cover crop mixtures (CCMs); 2) assess the impacts of cover crops on soil health and quality, soil moisture, cash crop, and profitability; and 3) disseminate project results and contribute to improved soil health management in the region. To date, we conducted 10 field trials and tested 19 CCMs. These trials encompassed two crop rotations (winter wheat-fallow and winter wheat-safflower-fallow), two tillage practices (conventional tillage and no-till), and conventional and organic crop production. CCMs were planted in late summer or in the spring and consisted of three to ten species of legumes, grasses, brassicas, and other plants. Two of the three growing seasons had below average precipitation. The 2017-2018 season was especially dry (42% of normal) and resulted in crop failure at six of the nine sites that had a cover or cash crop. Hence, the results are not conclusive yet but some some trends have emerged.

Late summer-planted cover crops produced significantly more biomass than the spring-planted ones. However, in general, the greater the biomass, the less soil moisture and soil NO₃-N was available to the cash crop. Moreover, when cover crops were planted too early after wheat harvest, volunteer wheat tended to dominate plant canopy and biomass. This can be mitigated somewhat with no-till and timely rainfall, and by minimizing wheat harvest losses.  Some cover crop species performed poorly (e.g. teff, flax, sunn hemp, balansa clover) and the notion that the more species (i.e., greater diversity) in the mix, the better may not hold true in the project area due primarily to water limitations. Hence, the climate in the region (semi-arid with short growing season), in addition to seed cost and proper management (i.e., planting date, seeding depth, inoculation) are key considerations for developing high performance cover crop mixtures. Winter wheat yields were lower following cover crops than after fallow and this is likely due to temporary immobilization of soil nitrogen and reduced soil moisture at planting. No fertilizer was applied to the wheat crop and this will be reconsidered moving forward. Input costs were higher and the returns were lower for the cover crop treatments, but we feel that with continued management refinements and the expected benefits (e.g., reduced soil erosion and improved soil health and quality) from cover crops, the costs will go down in the medium to long-term. Further testing and analysis will be done in 2018-2021 thanks to continued funding by Western SARE--Project SW18-500.

Detailed results for 2015-2016 and 2016-2017 were published in CSU-AES Technical Bulletin TB18-1. Project concepts and highlights were presented at multiple events including: two field tours, one field day, and over 20 workshops, conferences, and meetings. Many of these presentations, along with project announcements, interviews, and useful links are available on the project website at http://drylandcovercrops.agsci.colostate.edu. Attendance to the outreach events was generally good. Moreover, the attendees appear to have gained knowledge on cover crops, soil health, and management practices. These and other indicators bode well for the adoption of cover crops and other soil health improvement practices in the region.

Objectives/Performance Targets:

1. Evaluate the performance of cover crops and determine their effects on soil moisture, soil fertility, weed control, soil biology, soil erosion, and on the succeeding cash crop.

• Establish field trials on farmers’ fields and at the Southwestern Colorado Research Center (SWCRC).
• Collect baseline data at the start of each trial.
• Measure soil and plant characteristics annually to determine if and how cover crops affect dryland cropping systems in SW Colorado and SE Utah.

2. Assess the economic feasibility of cover crops in dryland cropping systems. Partial budget analysis was used to track changes in revenue that result from the operational and input costs associated with planting cover crops. Analysis includes measuring return on investment following cover crops, accounting for changes to yield or quality of cash crops. This will determine where a cover crop strategy produces a profit or loss to the operator. Indirect costs and benefits of cover crop management will be documented.

3. Educate farmers and others about cover crops and disseminate project results (all participants). This was achieved via:

• Yearly field tours and workshops
• Videos
• CSU-AES Technical Bulletin
• Presentations at growers' meetings, workshops, and other relevant events in Colorado and Utah
• The project website

4. Gauge the project’s impact by how well the outreach events are attended, feedback from each event, and the number of acres planted to cover crops since this project started. NRCS will continue to track the number of additional applications for cover crop grant assistance and will assist with long term monitoring of cover crop practice adoption.