Learning from farmer innovation in nitrogen fixation for improved nutrient management on organic farms

2010 Annual Report for LNE07-252

Project Type: Research and Education
Funds awarded in 2007: $99,108.00
Projected End Date: 12/31/2011
Region: Northeast
State: New York
Project Leader:
Julie Grossman
Cornell University
Laurie Drinkwater
Cornell University

Learning from farmer innovation in nitrogen fixation for improved nutrient management on organic farms


This past year we focused on winding down the work of this project. Our focus was on analyzing the results of the on-farm research and continuing with some limited outreach efforts. Currently, we are gearing up to publish a special issue on nitrogen fixing cover crops in The Natural Farmer. This extraordinary opportunity will enable us to develop a resource that will serve a wide audience of farmers and will capitalize on the combination of on-farm research and expertise of farmers who have developed innovative cover crop regimes.

Objectives/Performance Targets

  • Over 2000 growers and those working as grower educators will read answers to farmer questions on green manure management for BNF in our column
    Overall, the 60 farmers trained in green manure management for BNF will act as informal educators to another 60 farmers who were not directly trained
    Of the 50-60 farmers involved as workshop attendees, collaborators, or advisors, 25 will adjust their management of green manures within 6 months of project completion.


1. Newsletter columns: Two newsletter columns were published during 2010. Vicki Vetch continued to be carried by the NOFA newsletter: 1) The NOFA-NY newsletter ‘Organic Farms, Folks, and Foods’ is distributed to all NOFA-NY. We are offering these articles to the other newsletters that have carried Vicki Vetch in the past (Small Farms Quarterly and The Cornell Cooperative Extension newsletter VegEdge . Articles published in 2010 are listed below.

Drinkwater, L. E., and M. Gregory. (Winter 2010). Dear Vicki Vetch: The Why and How of Compost Analysis. Organic Farms, Folks, and Foods (vol. Winter 2010). Cobleskill, NY: The Northeast Organic Farming Association of New York.

Drinkwater, L. E. (2010). Dear Vicki Vetch: Clover-Grass Combinations for Cover-Cropping. Organic Farms, Folks, and Foods (vol. Spring 2010). Cobleskill, NY: The Northeast Organic Farming Association of New York.

2. On-farm survey plots to assess nitrogen fixation: We completed our work documenting on-farm nitrogen fixation rates. Our last round of samples were collected and analyzed. We have combined all of this data into a single database and are carrying out the analysis of the combined data. We continue to see the trends we initially reported last year: The proportion of N fixed by legumes consistently increased across virtually all farm sites when legumes were grown in mixtures with a non-legume. The total amount of N fixed in mixes varied, depending on the intensity of competition with the non-legume. We are still finding trends indicating that fields with very high soil fertility have reduced nitrogen fixation rates in legumes. Final results will be published in The Natural Farmer.

3. We are in the planning stages of a special issue to be published by The Natural Farmer in Summer 2011 focusing on how to manage N-fixing cover crops. This special issue will be available on the web and will serve as a resource for farmers and extension educators throughout the Northeast. Potential topics is provided below:
• Basic review of biological N fixation, legumes and their symbiotic bacteria (we have an overview of the biology and ecology of N fixation posted at http://www.hort.cornell.edu/extension/organic/ocs/tutorial/legume_n/index.html ).
• How much N are the different legume species actually fixing? red clover, field peas, vetch, bell beans (on farm data), research station–warm season legumes such as cowpea, soybean, berseem and crimson clover, chickling vetch
• What are the pros and cons of planting legumes as monocultures and in mixtures with grasses or other non-N fixing plants?
• Profiles of best bet cover crops of common niches in annual rotations. Profiles will cover multiple functions from the published literature as well as our own research: i.e. N fixation, weed suppression, soil organic matter and soil health improvements, P cycling, other special contributions (beneficial insects and microbes)
• Farmer narratives of favorite legume cover crop practices–we have some in mind that received very good reviews from our NOFA workshop
• How do soil management practices and the soil environment in organic grain and vegetable farms impact N fixation rates? What causes very low N fixation? What conditions support very high rates of N fixation? (This is based on measurements of N fixation on working organic farms)
• What are some rules of thumb for estimating how much N you are getting from green manures?
• What are some good strategies for optimizing N fixation in conjunction with other soil fertility practices?
• When and how to inoculate? What do we know about the bacterial communities in nodules?

Impacts and Contributions/Outcomes

1. We have continued reached more growers and extension educators through newsletters and presentations that originally expected. Thousands of growers have received information on nitrogen fixing cover crops through our newsletter column which is structured to publish responses to specific, grower-generated questions. Furthermore, more than 150 growers and extension educators who have participated in our workshops have learned how they can manage the biology of legumes and have also heard about practical tips for managing cover crops from expert growers. Our questionnaires indicate that significant proportion of these growers and extension educators plan to take action as a result of what they learned in these workshops.

2. We expanded our outreach plans due to the high level of farmer interest in the on-farm nitrogen fixation measurements we carried out as part of this project. We are working with Jack Kittredge to develop the content of the special issue on nitrogen fixing cover crops which will reach a broader audience than our newsletter articles. This publication will significantly broaden the scope of this project’s impact.


Carol MacNeil

[email protected]
Senior Extension Educator /Vegetable Specialist
Ontario County Coop Extension Association
480 N. Main St.
Canandaigua, NY
Office Phone: 5853943977
Greg Swartz

[email protected]
Interim Executive Director
Northeast Organic Farming Association of NY
PO Box 880
Cobleskill, NY 12043-0880
Office Phone: 8457968994
Website: www.nofany.org