Multipurpose Brassica cover crops for sustaining Northeast farmers

2003 Annual Report for LNE03-192

Project Type: Research and Education
Funds awarded in 2003: $158,570.00
Projected End Date: 12/31/2007
Matching Federal Funds: $113,673.00
Region: Northeast
State: Maryland
Project Leader:
Dr. Ray Weil
University of Maryland

Multipurpose Brassica cover crops for sustaining Northeast farmers


This project is designed to conduct on-station and on-farm research on multiple benefits from cover crops, with a special focus on Brassica species, in order to accomplish two related goals. First, the research results will demonstrate how multiple benefits can make these cover crops profitable enough to encourage wider adoptation of this sustainable farming practice by farmers in the NE. Second, the process used to conduct this research will empower and encourage farmers to conduct their own research on their own farms to generate objective answers to their own questions about cover crops and other farming practices. These goals will be achieved through four on-station field experiments that evaluate a range of cover crop species, management practices and mechanisms of beneficial effects, combined with on-farm research conducted by about 15 farmers. The farmer-research will address simple, focused questions about profitably fitting cover crops into specific farming situations. Results from at least 10 on-farm and 4 on-station experiments will contribute to a regional database on Brassica cover crops. This database will evaluate the practical effectiveness of various Brassica cover crops and mixtures in capturing residual nitrogen before it can leach away, and in providing lower cost and more sustainable alternatives to replace deep tillage for compaction alleviation, to replace fumigation for nematode and disease suppression, and to replace some herbicides and tillage for weed control. Extension educators, farmers and project personnel can use these results to promote appropriate and profitable uses of these practices. Project personnel will work closely with farmers and county extension educators to develop farm research interest and skills. Farmer participants will share their results and methodologies with other farmers, researchers and extension personnel via newsletters, conferences, presentations, field days, on-farm twilight tours, and discussion groups sponsored by Cooperative Extension and Future Harvest- Chesapeake Association for Sustainable Agriculture (FH-CASA). The project will work with farmers to use the experience and lessons learned to produce a user-friendly, visually-oriented guide to conducting on-farm research. The project aims to develop skills, experience and interest that leads to continuation of farmer initiated research activity and research support groups even after the project-funding period.

Objectives/Performance Targets

  1. Of the 450 horticultural and grain crop farmers reached by this SARE project, 40 will transition to the use of cover crops for two or more of the benefits demonstrated by the project research and 15 farmers will conduct Brassica cover crop research trials on their farms.

    Six of the farmers who participate in the design and implementation of trials to evaluate multiple benefits of Brassica cover crops on their farms will collaborate in the development of two farmer research guide booklets and participate in continuing farmer-to-farmer support of on-farm research.


This project requires that information on the Brassica cover crops be gathered and/or new information generated by field research before we can provide practical information and advise to farmers. However, while we are gathering and generating new information, we can and have reached out to farmers to generate interest in and to make them aware of the possible uses for these new (to our region) cover crops. We are also using the new cover crops as a vehicle to interest and empower farmers in to conduct their own research that provides reliable answers to their own questions farming practices. During the first year (really the 8 months since the project funding began in May, 2003) of the project, we have established field experiments on four different experiment stations and 8 replicated on-farm experiments on 5 commercial farms. Each on-station experiment is design to investigate several of the proposed Brassica cover crop benefits, as well as develop or validate information on the practical managment of these cover crops (such as planting dates, seeding rates, etc.). Most of the on-farm experiments are aimed at evaluating one specific cover crop function that addresses a problem perceived by the farmer. The main functions under investigation are:
• alleviation of subsoil compaction
• supression of plant parasitic nematodes
• reduction of weed pressure
• improvement of soil structure
• enhanced nitrogen capture and cycling

By December 2003 we have collected data on the biomass production of five different Brassica cover crops plus several combination of Brassicas with non-Brassica. We have begun to analyze the shoot and root biomass for N content and have taken deep soil cores to 180 cm to study the degree to the cover crops have cleaned up residual nitrate in the soil profiles. We have also completed some preliminary assessments of weed suppression in fall and nematode supression in a lab bioassay.

We began out outreach efforts by the publication of a preliminary fact sheet summarizing what we know or expect about the Brassica cover performance in the mid-Atlantic region. We also ran a story in the September Future Harvest newsletter which reached some 300 farmers (more than half way toward Milestone #1). In it, we call for “A Few Good Farmers” to join us in studying these cover crops and learning about farmer-research. To date we have received over 20 responses requesting more information by phone and email. Of these, 13 farmers expressed interest in participating next fall in on-farm research with the Brassica cover crops. These farmers are in addition to the five already mentioned as conducting on-farm Brassicas trial this season. Thus, we are about 20% of the way to Milestone #2. We are scheduled to participate at the Farming for Profit and Stewardship Conference in Hagerstown Maryland in January 2004 where we will conduct a workshop on the Brassicas and attempt to initiate a farmer research circle to address the performance targets. A questionnaire will also be distributed at this winter farmer conference. Several presentations by our Brassica cover crop team have also been scheduled at winter workshops at the request of extension agents.

Planned Milestones for years 1 and 2:
Milestone 1: About 450 farmers will hear about potential benefits of Brassica cover crop systems and farmer research through the initial project flier, extension, Future Harvest newsletters, farmer conference presentations, extension visits and direct phone calls. Fliers and newsletters passed out will be counted.
Milestone 2: One hundred of those farmers request more information on Brassica cover crops and on-farm research through the flier response form, emails, phone or web site responses.

Impacts and Contributions/Outcomes

We conducted a preliminary bioassay of plant tissue for nematicidal properties. Known populations of root-knot nematodes were added to wet sand containing varying amount of chopped leaves or roots from selected cover crops. Mixing 1% by weight of fresh oilseed radish leaves into sand cultures killed 60% of the nematodes initially added. Using a higher rate of oilseed radish leaves (5%) killed 100% of the nematodes. The other Brassicas and rye had significant, but lower, levels of action against the nematodes. To put the ratios of fresh tissue to sand in perspective, in mid-October (7 weeks after sowing) we measured shoot dry matter production by oilseed and forage radishes exceeding 5,000 kg/ha dry matter or about 50,000 kg/ha fresh weight. This represents a fresh tissue to soil mass ratio equivalent to about 2.5% or intermediate between those used in the bioassay. Tap root dry matter was about half as great as the shoot dry matter.
The Brassicas dry matter in this experiment contained 2.5 to 2.75% N, giving a total plant N uptake of about 150 to 170 kg N/ha in under 7 weeks of growth. Three replications of deep soil core data have been analyzed and they reveal that the radish plots were significantly lower in nitrate than the no cover plots down to 180 cm, the deepest samples obtained. The mean residual nitrate-N in the 180 cm deep profile was 45 kg N/ha for Forage Radish plots, 48 kg N/ha for the Oilseed Radish and 97 kg N/ha for the no-cover (winger weeds) plots, the Brassica effect being highly significant. These data are loamy sand soil to which 45 kg N/ha had been applied at cover crop planting in August. The data suggest that the radishes are highly efficient at rapidly cleaning up residual soil nitrogen before it can leach toward the groundwater.
Preliminary weed assesments in fall indicated that the radishes and rapeseed and a combination of forage radish and rye were all very competitive under extremely high weed pressure in another field experiment. For the early planting date (August 26), weed ground cover in November was 92 and 87% with out and with deep tillage but no cover crop, and only 9 and 11% with Oilseed and Forage Radish, respectively. A mix of two Mustard cultivars had poor establishment (seed rates used were too low) and the weed groundcover cover in that treatment was 32%.
While it is too early in the project to report on the farmer-adoption and research outcomes, we can report that so far five farmers are trying Brassica cover crops in collaboration with our project, and three of these were responsible for suggesting the basic objectives of the experiments on their farms. An additional 15 farmers have expressed interest in trying the Brassicas on their farms next fall.


Steve Groff
Cedar Meadow Farm
679 Hilldale Road
Holtwood, PA 17532
Office Phone: 7172845152
John Teasdale
Weed Scientist and Research Leader
USDA/ARS, Sustainable Agric. Systems Lab
Wallace Agric. Research Center
Bldg. 001 Room 245
Beltsville, MD 20705
Office Phone: 3015045504
Sandra Saardanelli
IPM Coordinator and Nematologist
University of Maryland
H. J. Patterson Hall, Rm. 2105
University of Maryland
College Park, MD 20742
Office Phone: 3014057877
David Almquist
County Extension Director & Extension Educator, Ag
Harford County Extension Cooperative Extension
Caragh Fitzgerald
Extension Educator, Agriculture & Natural Resource
Howard County Cooperative Extension
Office Phone: 4103132710