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

View the project final report

• 2012 annual report
• 2013 annual report
• 2014 annual report

Commodities

• Agronomic: wheat

Practices

• 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

Final Report SW11-099 Apr 2016 cj

We measured effects of cover crop mixes (CCMs) grown during the fallow period on soil properties, water use, and wheat yield. CCMs included plant groups that 1) fix nitrogen, 2) provide ground cover, 3) have deep tap roots, or 4) have fibrous roots. Farmer-conducted field studies showed important soil water and nitrogen use, and reduced wheat yields compared with fallow. Water use and yield loss was less in plot-scale studies due to earlier termination. Compared with chem fallow we documented soil cooling, enhanced soil biological activity, and generally better wheat response with legume vs. non-legume cover crop mixes.

1. Position this project for maximal success by gaining familiarity with growth characteristics of targeted candidate species for CCM’s by growing crops locally in 2011 prior to potential award of this grant.
   1. 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.
   2. To ensure success of our field research, we will monitor nearby farm fields of CCM’s, as time and budget permits, to gain familiarity with sampling CCM’s and with practical field challenges.
2. Quantify the effects of CCM’s (compared with fallow) on grain yield, quality, and economic return compared with fallow
   1. We will determine differences (with 90% confidence) in yield and quality of grain following each CCM compared to fallow for 4 plot studies and 6 field scale studies following the 2nd year of the study.
   2. 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 CCM’s 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 CCM’s on soil quality using fallow as a control
   1. 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).
   2. Comparing CCM’s 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.
   3. 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 CCM’s 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 CCM’s
   1. 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.
   2. Our second performance objective will be to increase the audience awareness and understanding of potential benefits of CCM’s. We will assess this with audience evaluations.
5. Educate audience about effects of CCM’s on subsequent crop and economics
   1. 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 2000 indirectly.
   2. Our second performance target will be to increase our audience’s understanding of the agronomic and economic effects of CCM’s in our region. This will be assessed with evaluations.
6. Educate audience about the effects of CCM’s on soil quality, including functional group benefits, based on our study
   1. In the year of the 2nd 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 1200 indirectly.
   2. 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 CCM’s.