The integration of cover crops is gaining popularity with producers as a way to improve soil health, minimize inputs and create more resilient agricultural systems. While cover cropping is gaining attention nationally, only a handful of producers in the Palouse region of the inland Pacific Northwest are experimenting with cover crops due to a lack of regionally specific research and resources. To address this need, Lester Wolf Farms INC., the Palouse Conservation District and local Natural Resource Conservation Service staff will work together to develop an economically sustainable cropping system, integrating cover crops in the high precipitation zone of the Palouse region to promote soil health, and eventually reduce synthetic fertilizers and herbicides. This three year project will experiment with fall seeded cover crops in the traditional winter wheat-spring wheat-pulse rotation. A block design containing six strips, three business-as-usual strips (control) and three cover crop strips (treatment), will be set up in all three of the traditional crops planted, resulting in 3 blocks and 18 strips. Soil physical and chemical data will be collected in each strip along with crop yields and farm level inputs to calculate relative profitability. Results will be shared through field tours, stakeholder workshops, fact sheets, a peer reviewed article and a video. Expected outcomes include: a reduction in glyphosate application; information on cover crops as a weed management tool; information on cover crop mixes, seeding rates and the support of cover crop seed vendors and consultants and; increased nitrogen fixation resulting in lower nitrogen inputs.
The overarching goal of this study is to develop an economically sustainable cropping system that will integrate cover crops with cash crops in the high precipitation zone of the Palouse to promote soil health, and eventually reduce or eliminate synthetic fertilizers and herbicides.
This goal will be accomplished through the following objectives:
- Assess the effects of successfully established fall and spring cover crop mixes on weed pressure and key chemical and biological indicators of soil health.
- Evaluate and compare the economic returns of the selected cover crop mixes vs. business-as-usual (no cover crops) in the high precipitation zone of the Palouse.
- Develop and disseminate management recommendations for farmers based on these results through field tours, stakeholder workshops, fact sheets, a peer reviewed article and a video featuring the project that highlights successes, failures and recommendations for new adopters.
- - Technical Advisor
- - Producer
Lester Wolf Farm INC. will partner with the Palouse Conservation District (PCD) and the Colfax Natural Resource Conservation Service (NRCS) office to meet the goals and objectives outlined for the project. The materials and methods used to achieve these objectives are outlined below.
Objective 1: Assessing the effects of cover crop mixes
The Lester Wolf Farm is typically cropped with soft white winter wheat, soft white spring wheat, and garbanzo beans in a 3-year rotation. Cover crop treatments will be tested at each point in this rotation, so trials will be conducted in three separate fields at the different rotation intervals over three years. Paired plots will be used to compare the cover crop treatment to control (randomly assigned within each block). Each plot will consist of a minimum 400 ft long strip planted with a 36ft wide Cross Slot drill (2 passes). There will be three replications per treatment; refer to Figure 1. Following winter wheat harvest, the goal is to test a fall planted winter hardy cover crop mix, and allow this mix to grow into spring, seeding the next year’s spring wheat crop into the growing cover crop, and terminating the cover crop with appropriate herbicides based on both the cash crop and cover crop’s growth characteristics. The goal is to prolong growth of the cover crop to maximize nitrogen fixation.
Following spring wheat harvest, a different fall planted winter hardy cover crop mix will be tested, and allowed to grow into spring, seeding the next year’s garbanzo crop into the growing cover crop, and terminating the cover crop with appropriate herbicides based on both the cash crop and cover crop’s growth characteristics.
Succeeding garbanzo harvest, winter wheat will be planted with an inter-seeded cover crop mix. This mix will be allowed to grow into the following spring and terminated based on both the cash crop and cover crop’s growth characteristics.
Cover crop establishment and success will be measured using a point intercept method to estimate percent cover of cover crop species, cash crop, and weeds; once prior to snow fall, approximately mid to late November, and prior to termination in the spring. Five clip plots along each transect will be taken to estimate cover crop, cash crop, and weed biomass prior to termination. Every spring, when the soil is at field capacity, soil samples will be taken and soil physical measurements will be collected. A minimum of 10 soil samples will be collected randomly assigned locations in each strip to a depth of 30 centimeters. The samples will be well mixed and composited into a single sample representing the entire strip. Soil chemical and physical parameters will include total soil organic carbon, ratios of active fungi and active bacteria, permanganate oxidizable carbon (POXC), micro and macro nutrients, penetrometer readings and infiltration rates. The cash crop will be harvested with a combine, and yield data will be collected with one combine pass per plot.
Paired t-tests will be used to compare control to treatment for the following data parameters: a) percent cover of cash crop, cover crops, and weeds; b) Biomass of cash crop and weeds; c) soil organic carbon, active fungi/active bacteria, POXC, nitrate and ammonia and; d) cash crop yields. Analysis will be conducted in R, statistical software, using a linear regression model and model assumptions of normality will be used to verify the validity of analysis, and to inform any data transformations.
By conducting this research at every rotation interval, this allows adaptive management to adjust seed mixes, timing of seeding, timing of termination, and other necessary adjustments. Initial cover crop mixes and rates will be based on the resources available from the Natural Resources Conservation Service, and on-farm experimentation that Lester Wolf Farms INC has collected over the last 10 years. The fall seeded cover crop mix following winter wheat currently consists of a three clover blend, radish, and turnip. The fall planted cover mix following spring wheat includes fall triticale, fall oats, canola, turnip, and chicory. Winter wheat will be inter-seeded with a blend of three clovers.
Objective 2: Economic return of cover crops vs. business as usual
An economic analysis of the strip trials associated with this experiment is important in determining the feasibility of integrating cover crops into the traditional cropping systems of the Palouse Region. Lester Wolf Farms will diligently track all input costs including seed, fertilizer, fuel, and pesticides for each crop year and control and treatment strip in the block design outlined in Figure 1. Crop yields for each strip will be collected with a yield monitor on the combine and recorded. Relative profitability for both control and treatment will be calculated by subtracting input costs from crop yields multiplied by relevant wheat price data. A paired t-test will be used to compare control and treatments using R statistical software.
Objective 3: Develop and disseminate management recommendations
The lack of regionally specific information on integrating cover crops into typical crop rotation has been noted by many producers in the Palouse Region as a barrier to adoption. This project will address this need by hosting field days, facilitating stakeholder focus groups, attending conferences, disseminating fact sheets, writing a scientific publication and producing a video about the project. More specifics about the educational outreach activities and materials can be found in the next section and are outlined in the attached timeline.
Materials and methods in year one of the project:
In the first year of this project eight one acre strips of cover crop mixes were seeded and compared to two one acre control strips in spring wheat, winter wheat and pea crop rotations. Four strips were interseed with spring wheat examining warm season mixes (SW_interseed, SW_interseed_mix_1, SW_interseed_mix_2) and one strip of a cool season mix was broad cast over growing spring wheat (Over_Winter_3). In winter wheat, two strips were broadcast over the wheat in June focusing on a cool season mix with different seeding dates (Over_Winter_Winter_1, Over_Winter_Winter_2) and one strip of a warm season mix was interseeded in May (Nestor_Mix). The final strip trial contained a warm season mix interseeded with peas in April (Pea_interseed). Table one below outlines the cover crop mixes, seeding method, seeding dates, seeding rates, termination method and dates, and cost of seed in both the winter wheat and spring wheat trials. The strips were seeded between April 8 and June 18, 2021.
Within five of the above mentioned strip trials and winter wheat and spring wheat controls soil samples were collected following seeding in late June. A minimum of five sampling locations were randomly selected in each strip and five samples were collected in a circular pattern at each location. Samples were collected with a JMC backsaver soil probe to a depth of 30 centimeters, and all of the samples were well mixed into a composite sample representing each strip. The samples were stored in a cooler and composite samples were shipped to Woods End Laboratories, INC and Soil Test Farm Consultants Inc. for analysis. Our initial plan was to sample each of the strips but this became logistically challenges due to Covid-19. All of the strip trials will be sampled in early April, 2021. Photos of the strip trials can be seen in Figure 2 below.
Cover crop establishment and success was planned to be measured with the point intercept method to estimate percent cover of cover crop species, cash crop, and weeds. Our original plan was to do this once in the spring prior to termination and once in the fall prior to the first snow fall. Logistical complications due to the Covid-19 pandemic stopped this from occurring in spring but visual assessments did occur following harvest for the cool season cover crop strips.
Following harvest, crop yield data and input costs were compiled in an excel spreadsheet and differences in net income were calculated between the control and the cover crop strips. Gross income for each strip trial was calculated by multiplying the crop yield by 2020 crop selling prices. The selling prices were as follows: Winter wheat = $5.15/bushel, Spring Wheat = $ 5.97/bushel, and peas = $0.12/Lb. Net income was calculated as Gross income mins total input costs. Finally, The difference in net income from the control strips were calculated as net income minus the input costs for cover cropping.
Results from soil sampling in the cover crop strip trials and the control strips indicate both positive and negative differences in the parameters measured (Table 2). In in the warm season mixes interseed with spring wheat increased levels of Solvita CO2 burst, total carbon, water soluble organic carbon, and estimated nitrogen mineralization were observed when compared to the controls. Decreased levels of water soluble nitrate-N and Permanganate Oxidizeable Carbon were seen when compared to the controls. The strip seeded with the SW_interseed mix that was made up of collards and purple top turnips was the only strip that had positive differences from the spring wheat control strip for all parameters measured. The sampling in the cool season mix strip trials (Over_Winter_1, Over_Winter_2, and Over_Winter_3) in both the spring wheat and winter wheat strips had mixed results when compared to the control strips. This was somewhat expected as fields are variable and at this point, the goal of sampling these strips was to develop baseline data that can be used to evaluate changes over the next two years.
Soil sampling will continue in early April of 2021 to continue to evaluate differences from the control strips and the over winter seeded mixes seeded in the spring of 2020. We intend to collect replicates in each cover cropped and control strip, enabling us to analyze the results for statistical significance.
Economic data on input costs and crop yields for the cover crop strip trials can be seen in table 3 below. At this point in the project this analysis would indicate that all the strips are returning losses between $8.00 and $25.00 when compared to the control strips. While this could be deal breaker for many producers, costs and benefits following cover crops have not yet been fully identified. Over the next two years we intend to quantify the risks and returns associated with soil chemical and biological differences associated with the cover crop strip trials.
Lessons learned from a farming perspective:
This years trials gave us some important takeaways for next years trialing of dos and don’ts. We learned the importance of cover crop plant types, seeding dates, seeding depth, seeding rates, and termination response.
Plant Types: We tried a diverse mix of cool and warm season plants within the mixes. We found with all seeding methods and different dates the warm season did not establish or thrive. For spring seeded cover crops in our area the warms seasons should be eliminated and subbed out for more aggressive cool season plants that will establish to obtain our goal of O.M. growth, weed controls and nutrient cycling.
Seed Dates: Establishment of covers did best when applied at the time of seeding of cash crop. The cover crops inter-seed with a no-till drill, established but caused to much damage to the cash crop along with to much competition from the crop to add any benefit. The broadcast seeding had very limited to no establishment and should not be repeated.
Seeding Depth: If all plantings are to happen at same time of seeding with the cash crop it is important to pick cover crops that can establish at the same depths the commodity crop is being seeded. This needs to be paired with plants that can establish in the soil/environmental conditions of the cold wet spring in the Pacific North West.
Seeding Rates: While we had great establishment of the covers crop seeds in the inter-seeded plots our rate were just too low. Going forward we will increase the rates higher on the cool season plants along with the elimination of the warm season plants. We lacked competition and gained no weed suppression.
Termination: Plots were terminated at our traditional time of spraying herbicide for weed control. This date should be pushed out to gain affects from the inter-seeded legumes. If denser establishment of cover crops exist and weed pressure is lowered the hope is to gain an addition 14-21 days of additional growth from the cover crops before termination.
Educational & Outreach Activities
Palouse CD will work with Lester Wolf Farms to coordinate a field tour in the third year of the project at the farm. With two years of data collected and analyzed, results will be shared with interested producers and agency personnel in the area. Field days are hosted annually by PCD and have regularly drawn crowds of over 100 producers and agency staff members. In addition to the field day, a stakeholder focus group will be formed, containing producers in the region that are specifically interested in integrating cover crops into their cropping system. This group of seven to 10 individuals will meet three times between November and March for the duration of the project. The group will discuss the status and progress of this project, as well as on farm trials that are being conducted outside of this scope of work. This producer to producer network will help to spread information generated from this study as well as provide a forum for peer to peer education.
The information generated from this project will also be shared in the second and third years at two conferences. The Pacific Northwest Direct Seed Association hosts an annual Cropping Systems Conference, in January in Kennewick, Washington. Producers throughout the Pacific Northwest come together to share lessons learned from on farm trials, learn from innovative producers outside of the region and hear about the latest advances in technology from industry leaders. The second conference, the Palouse Alternative Cropping Symposium is hosted annually in February by PCD in Pullman, Washington. This is a smaller event specifically focused on cover cropping, livestock integration and alternative crop rotations. This project will be featured at both of these events via PowerPoint presentations.
Education and outreach materials will also take on more traditional forms with fact sheets being created at the end of each crop year. The fact sheets will outline the cover crop mixes used, crop yields, relative profitability, and results from the physical and chemical soil tests. The fact sheets will be distributed at PCD events and will be publicly available on their website. Building off of the fact sheets, PCD will work with NRCS Resource Conservationists to compile all the data collected into a peer reviewed article that will be submitted at the end of the third year of the project.
The final component of the outreach and education efforts will include producing a video that documents the progress of the project, the successes and most importantly the lessons learned. Throughout the course of the project Lester Wolf Farms and PCD will record extensive components of the project and will compose the video in the third year. The footage will also include interviews with employees from Lester Wolf Farms, PCD, NRCS as well as other producers that are experimenting with cover crops. The video will be posted on the PCD’s website, social media pages and on Vimeo. Specific details on when each of these activities will be completed can be found in the project timeline.
Education and outreach activities in year one of the project:
Significant progress was made at completing the education and outreach objectives outlined for this project in the first year. There were some delays due to the Covid-19 pandemic, we were unable to form and meet with a stakeholder focus group in this first year. We don’t expect this will have significant impacts in meeting any of the objectives moving forward. Preliminary information from the first year of the cover crop plot trials was shared at the “Soil Health Site Down” event hosted by the Palouse Conservation District on January 20, 2020 from 7 to 8 am. There were 41 individuals present, 15 farmers or ranchers and 26 agricultural professionals. A recording of the presentation can be found here and a pdf of the presentation is pasted below.
Additional education and outreach activities included collecting video footage during seeding and through out the growing season. This will continue through each growing season. The footage will be used for an educational video that will be released in the fall or winter of 2022. Lester Wolf farms and Palouse Conservation District have also started talking about planning a small, invite only, field tour that we hope will be able to take place this summer. Additionally, once data is compiled from the over winter (fall seeded) strip trials is compiled management summaries will be created and distributed.
After completing the first year of the project it is somewhat difficult to determine how it has effected agricultural sustainability in the region but we anticipate that it could contribute to future sustainability. This project along with several others in the region are attempting to figure out cover crop mixes, seeding dates and crop rotations that will enable growers to viably integrate cover crops into the standard rotations. The information generated from this first year provides a snapshot into the cover crop mixes tried, seeding dates, seeding rates and economic data associated with each strip. While it is hard to make any solid conclusions at this point, sharing this information and the lessons learned with other interested growers will help them make decisions for their own experiments and trials.