Incorporating Cover Crops and Green Manure in High-Desert Organic and Conventional Farming Systems

Incorporating Cover Crops and Green Manure in High-Desert Organic and Conventional Farming Systems

Summary

Both conventional and organic growers in southern Idaho express interest in finding affordable soil additives to replace or reduce commercial fertilizer use. The results from two on-farm research trials and a UI research station trial have been used to 1) identify cover crops suitable for high-desert farming systems, 2) identify optimal mixtures of cover crops for different management goals (i.e. soil, weed & pest, soil compaction, and forage), and 3) planting and management of cover crops in high-desert farming systems. Data has been collected on each species for pre- and post-soil nitrogen content, cover crop yields, cover crop forage quality-dual-purpose, and percent nitrogen in cover crop tissue. This project has provided well-needed outreach to an estimated 10,000 growers in the local and regional area through presentations. In addition, project outcomes include eight publications for extension, scholarly proceeding articles, and two articles in a trade magazine. Remaining project goals include evaluating the economic benefits associated with planting cover crops for soil nutrient management.

Objectives/Performance Targets

Objective 1. To increase research-based knowledge on cover cropping systems for soil and weed management in high-desert farming systems.

Objective 2. To compare nitrogen additions from cover crop species and mixtures grown in high-desert farming systems.

Objective 3. To evaluate the economics of on-farm cover cropping systems by establishing return on investment with cover crop integration.

Objective 4. To increase adoption of cover crops for sustainable soil management.

Objective 5. Compare forage quality and yield of dual-purpose cover crop species and mixtures.

Accomplishments/Milestones

Table 1. Summary table of milestone accomplishments from 2012 to January 2015.

The PIs and the hired help (with Western SARE funding) set-up three replicated research sites for high-desert cover crop species in 2012 and 2013. Data collected from both years included pre- and post-soil samples from each replicated plot, cover crop yield, cover crop forage quality, and percent nitrogen in cover crop tissue. The survivability and characteristics associated with each tested cold-hardy cover crop species has been summarized and compiled for outreach and publication efforts. Over 60 producer and professional presentations have been given as a result of the  research trials. Publications include one UI Extension publication, five peer-reviewed proceeding articles, and five peer-reviewed abstracts. Two trade articles for home gardeners and small farmers were written for Zone 4 Magazine, Fall 2013 and Winter 2014 Edition, “Cover Cropping at High Elevations, Part 1: Selecting and Planting Cover Crops for Fall” and “Cover Cropping at High Elevations, Part 2: Managing Soil Nutrients with Cover Crops.”

Regional audiences in the intermountain west have been reached from this projects outreach efforts at the 2012 National Association of Western County Ag Agents, the 2012 and 2014 Idaho Nutrient Management Conference, the 2013 American Forage and Grassland Conference in Memphis, TN, and the Western Alfalfa and Forage Symposium in Reno, NV.

Additional outreach by PIs includes five Cover Crop Field Days. Western SARE grant money was used to purchase supplies for the field tours.

Final cover crop data will be collected in spring/summer of 2014. There will be planned presentations on the cover crop project in 2014 and 2015.

Impacts and Contributions/Outcomes

Objective 1. To increase research-based knowledge on cover cropping systems for soil and weed  management in high-desert farming systems:

The three trials have identified optimal cover crop species for high-desert farming systems. The research findings from Western SARE helped to start a second cover crop outreach project through an NRCS Conservation Initiative Grant. This project features 10 on-farm demonstration trials at influential producer sites throughout southern Idaho.

Objective 2. To compare Nitrogen additions from cover crop species and mixtures grown in high-desert farming systems:

The three trials generated data on species/mixtures and soil nitrogen contribution and soil nitrogen scavenging abilities. The data has been statistically analyzed and used for grower presentations, consultations, and publications. The cover crop research demonstrated 12 cover crop species, grouped into nitrogen-fixing (ex. Austrian winter pea, arvika pea), grass/grains, (ex. triticale, sorghum Sudangrass), and brassicas (ex. daikon radish, canola), that can be planted alone or in a mix to obtain multiple agronomic benefits. For example, a cover crop mix of canola, triticale, Austrian winter peas, and vetch helps to scavenge nutrients, increase organic matter, fix nitrogen, and control weeds. Cover crops offer an organic source of nitrogen for both conventional and organic producers. The tested Idaho cover crops contributed between 16-75 lbs per acre of plant available nitrogen in the spring following a fall planting. A legume and triticale mix contributed the most nitrogen to cash crops (ex. hairy vetch/triticale, Austrian winter peas/triticale, and arvika pea/triticale). The Idaho cover crop research identified the ability for tested brassica species to scavenge nutrients from the soil profile. A canola and triticale mix scavenged 260 lbs/acre of nitrogen after 55 days of fall growth. This nutrient scavenging protects water resources by minimizing nutrient run-off.

Objective 3. To evaluate the economics of on-farm cover cropping systems, by establishing return on investment with cover crop integration:

In press: publication looking at the economic advantage of grazing cover crops.

Objective 4. To increase adoption of cover crops for soil fertility management:

By reaching over 10,000 producers with research-based information for optimal use of cover crops, PIs have increased adoption of cover crops in the intermountain west. The research was published and presented throughout Idaho and increased grower adoption. In winter of 2014, the Idaho cover crop research was presented at four UI Extension Cereal Schools in eastern Idaho where 332 participating producers were surveyed on current use and future adoption of cover crops. Currently, 16% of producers at the cereal schools use cover crops. After presenting Idaho cover crop research, 48-79% are willing to adopt cover crops with one-third of these producers planning to adopt by the 2015 growing season. The participating producers indicated they would adopt cover crops to achieve multiple management goals, such as to minimize soil wind erosion loss, supplement soil organic matter and nitrogen levels, and scavenge soil nutrients. If one-third of the participants implemented cover crops by 2015, an estimated 94,500 acres of cover crops would be planted in eastern Idaho.

Extension Educators partnered with NRCS and two Soil Conservation districts to further increase cover crop adoption in Idaho. The research team planted cover crops at eight on-farm demonstration sites, ranging from 2 to 15 acres, throughout the Magic Valley. By having satellite sites across southern Idaho, non-participating producers are able to critically evaluate how the multi-species cover crops perform under a wide range of soil types, irrigation systems, and climate. Through the use of satellite sites, Idaho cover crop adoption will continue to increase and contribute to the national goal of 20 million acres of planted cover crops by 2020.

Objective 5. Compare forage quality and yield of dual-purpose cover crop species and mixtures:

Producers are more willing to adopt cover crops if the money spent on seed can also be used for grazing/forage. PIs have utilized yield and forage quality data on cover crop species to help market cover crops for a dual-purpose, soil and forage use. This information has been summarized in two regional proceeding articles and presented at two regional and national conferences. 

Collaborators: