Increasing Grower Adoption of Adaptive Cover Cropping Systems: Effects on Vegetable Production and Nitrogen Cycling

Increasing Grower Adoption of Adaptive Cover Cropping Systems: Effects on Vegetable Production and Nitrogen Cycling

Summary

To date, we have conducted two years of on-farm cover crop trials at five participating farms. Cover crop biomass and nitrogen content of cover crops were measured. Soil nitrate, active carbon, water infiltration, bulk density and crop yields were measured in subsequent vegetable crops. Findings have been used to validate development of the cover crop N-mineralization model in the OSU Organic Fertilizer and Cover Crop Calculator: http://smallfarms.oregonstate.edu/calculator.

Findings from this project have been presented at 18 extension events to an audience of over 800 people. It has also been incorporated into the Growing Farms beginning farmer training curriculum (http://smallfarms.oregonstate.edu/growing-farms-workshop-series). Findings have also been presented five times at professional meetings to an estimated audience of 160.

The project is helping growers better estimate cover crop nitrogen contributions and understand some of the soil quality benefits of cover crops. Growers are also learning ways to incorporate cover crops in their vegetable rotation using innovative seeding strategies such as relay seeding.

Objectives/Performance Targets

Our objectives are to:

1. Collaborate with growers to identify adaptations to cover cropping systems in commercial vegetable rotations.

2. Improve our ability to quantify N and soil quality benefits of cover crops over a number of years.

3. Increase farmer confidence in, and use of, N mineralization estimates and soil and plant tissue testing methods to determine nitrogen input needs (need for fertilizers, manures, composts) for the summer vegetable crops.

4. Extend project findings to a larger audience.

Accomplishments/Milestones

1. On-farm trials and demonstration projects have been conducted for two years on five farms. Treatments include phacelia and common vetch, cereal rye and common vetch, common vetch alone and bare ground fallow. Each main plot was split into a full-rate N application (as feather meal) and 0-N. A one-year trial was conducted at the North Willamette Research & Extension Center. Main plot treatments were cereal rye and common vetch, common vetch alone, compost and bare ground fallow. Each main plot was split into a 0-N, half-rate N and full-rate N application (as feather meal). Cover crop biomass and N content was measured in the spring. During the growing season, cover crop plots were split into 0-N and full-rate N application rates, and soil nitrate was monitored during the growing season. Cover crops increased soil N concentrations by between 30-80lbs/acre. When soil nitrate levels were low, this extra N increased crop yield. Some improvements in water infiltration were also seen in cover crop plots. Active Carbon samples are still being analyzed. Complete research findings will be included in the final report.

2. Educational tools: Findings from this project have contributed to development of the online Organic Fertilizer and Cover Crop Calculator and website. Andrews and Sullivan and two participating farmers (Bronec and Brown) have presented findings from this work via one eXtension webinar (eOrganic), two beginning farmer training sessions (Growing Farms), two newsletters (Oregon Small Farm News), 14 extension presentations to over 800 participants and five professional meetings to an estimated 160 participants.

a. Organic Fertilizer and Cover Crop Calculator: http://smallfarms.oregonstate.edu/calculator. The calculator helps growers estimate nitrogen mineralization from cover crops and organic fertilizers, compare the cost of different nutrient management programs and match fertilizer application rates to crop requirements while crediting cover crop nitrogen.

b. eXtension content: Estimating Plant-Available Nitrogen from Cover Crops (April 13, 2010). Broadcast from OSU in Corvallis. eOrganic webinar. 35 participants.

c. Growing Farms Content: Soil Fertility module (February 24, 2010 and February 9, 2011). 65 participants to date.

d. Oregon Small Farm News articles

i. Andrews, N. (2010). Establishing Winter Cover Crops. Oregon Small Farm News. 5(4), pp 17-20.

ii. Andrews, N. (2010). OSU Cover Crop Calculator to be Launched in Early April. Oregon Small Farm News. 5(2), pg 12.

e. Extension presentations:

i. Organicology: Soils Intensive (February 10, 2011). “Within Season Nitrogen Management on Organic Vegetable Farms,” and “Nutrient management tools” (Andrews and Doug Collins from WSU). About 60 participants.

ii. Estimating Cover Crop Nitrogen Contributions & Using the OSU Organic Fertilizer & Cover Crop Calculator (January 6, 2011). Annual Organic Grower’s Meeting, GS Long. Yakima, WA. About 70 participants.

iii. Nitrogen Management and Cover Crops in Organic Vegetables: OSU Organic Fertilizer and Cover Crop Calculator (November 13, 2010). Port Townsend, WA. Washington Tilth Producers Conference. Invited out of state. 80 participants.

iv. OSU Organic Fertilizer and Cover Crop Calculator (October 5, 2010). At NWREC. Shade Tree Grower’s Meeting. North Willamette Research & Extension Center. 18 participants.

v. OSU Organic Fertilizer and Cover Crop Calculator (September 7, 2010). At NWREC. Nursery Field Day. 40 participants.

vi. OSU Organic Fertilizer and Cover Crop Calculator: A New Tool for Estimating Cover Crop Costs and Benefits (August 19, 2010). Philomath, OR. Presenter at Benton County SWCD Soil Quality Workshop. 50 participants.

vii. Estimating N From Cover Crops and Choosing Organic Fertilizers (July 30, 2010). At OSU in Corvallis. Master Gardener Mini-College. 60 participants.

viii. Soil Fertility and Cover Crops (June 10, 2010). Near Salem, OR. Willamette University Student Farm. 8 participants.

ix. Nitrogen Management and the OSU Cover Crop Calculator (April 13, 2010). At OSU in Corvallis. Department of Horticulture Seminar. 10 participants.

x. Nitrogen Management on Organic Farms (Aprril 6, 2010). In Albany, OR. Natural Resource Conservation Service, Animal Waste Management Workshop. 40 participants.

xi. Cover Crop Research and Fertilizer Calculators (March 6, 2010). Kamloops, BC. Certified Organic Associations of British Columbia annual conference. 50 participants. Presentation posted online.

xii. Using Cover Crops and the OSU Cover Crop Calculator (February 27, 2010). At OSU in Corvallis. Organized session and delivered presentation at OSU Small Farms Conference, session repeated twice. 170 total participants.

xiii. Cover Crop and Irrigation Field Day (January 14, 2010). On farm in Canby, OR. Planner and instructor. 10 participants.

xiv. OSU Cover Crop Calculator (January 12, 2010). In Canby, OR. Presentation at Organic Crops Section of the North Willamette Horticulture Society Meeting. 165 participants.

f. Professional Meetings and Conference Proceedings:

i. Andrews, N., D.M. Sullivan, J.W. Julian and K.E. Pool (March 3-4, 2011). Development and Use of the OSU Organic Fertilizer and Cover Crop Calculator. Proceedings of the 2011 Western Nutrient Management Conference, Reno, NV. 30 participants.

ii. Sullivan, D.M., R. Datta, N. Andrews and K. E. Pool (March 3-4, 2011) Predicting Plant-available Nitrogen Release from Cover Crop Residues. Proceedings of the 2011 Western Nutrient Management Conference, Reno, NV. 40 participants.

iii. Andrews, N. and D.M. Sullivan (October 31-November 3, 2010). In Long Beach, CA. Estimating Cover Crop Nitrogen Contributions and Management Costs with a New Online Calculator. Soil Science Society of America Conference. Oral paper. About 40 participants.

iv. Sullivan D.M. and N. Andrews, J. Luna, A. Garrett, R. Datta, and K. Pool (October 31-November 3, 2010). In Long Beach, CA. Monitoring Crop Nitrogen Status in Organic Vegetable Cropping Systems. Soil Science Society of America Conference. Oral paper. About 50 participants.

v. Sullivan, D.M., N. Andrews, J. Luna and J. McQueen (August 1-6, 2010). In Brisbane, Australia. Estimating N contribution from organic fertilizers and cover crop residues using online Calculators. 19th World Congress of Soil Science.

3. Partnerships: This project has led to two new partnerships with the Natural Resource Conservation Service and Soil and Water Conservation Districts in Oregon. West Multnomah SWCD has partnered with Andrews to work with growers in their district to optimize N fertilizer use by increasing adoption of cover crops and crediting non-fertilizer N, including cover crop N and use of the Organic Fertilizer and Cover Crop Calculator. As a result of the research and outreach activities of this project, NRCS Tualatin SWCD’s have adopted the Calculator in their nutrient management programming. When growers develop nutrient management programs under the new Organic EQIP program, they are instructed to use the Organic Fertilizer and Cover Crop Calculator. A new partnership with Washington State University is also developing in part from this project. Andrews and Doug Collins (WSU Extension) collaborated on development of a one-day Soils Intensive workshop at Organicology in 2011. About 60 people attended the workshop which included demonstrations of the OSU Calculator and an introduction to a new soil sampling and nutrient management database being developed by Collins that will help growers keep track of soil test information and develop fertilizer recommendations. We intend to explore ways to combine the OSU calculator with the new WSU tool. Collins, David Granatstein and Carol Miles (WSU Extension) have all used the Calculator in the research and extension work. Andrews and colleagues at OSU have also collaborated with Collins and colleagues at WSU in a new grant proposal to investigate cover cropping and reduced tillage strategies.

4. Future work. The project is entering its final year. In the final year we will conduct:

a. On-farm trials focus on relay seeding;

b. Data analysis and interpretation: soil nitrate, water infiltration, active carbon, bulk density;

c. Additional outreach and survey of participating growers.

Impacts and Contributions/Outcomes

As a result of this project, growers are increasing adoption of cover cropping in their vegetable rotations and improving their understanding of how cover crops benefit soil structure and tilth. The online OSU Organic Fertilizer and Cover Crop Calculator also helps growers to quantify nitrogen benefits from cover crops and organic fertilizers, select the most cost effective fertilizers and match fertilizer rates to crop nutrient requirements. It is too early to quantify the impacts of the recently expanded calculator, but the previous version (OSU Organic Fertilizer Calculator) was downloaded about 4,800 times by May 2010 (when the expanded calculator was posted online). It had over 1,300 registered users from 64 countries representing every continent. Of the users, 1040 are in the U.S., representing all 50 states. There were 344 registered users in Oregon, 165 in Washington and 107 in California. Estimated annual economic impact of the Organic Fertilizer Calculator was more than $500,000. Similar impacts are expected from the Organic Fertilizer and Cover Crop Calculator.

Collaborators: