Nitrogen and Soil Quality Benefits of Radish as a Cover Crop

View the project final report

Commodities

• Agronomic: corn, wheat
• Vegetables: radishes (culinary)

Practices

• Crop Production: conservation tillage
• Education and Training: extension, on-farm/ranch research
• Production Systems: general crop production
• Soil Management: soil analysis, soil chemistry, soil physics, soil quality/health

Oilseed radish (Raphanus sativus L) has become a popular cover crop option in the Midwest for the late summer, especially among no-till farmers. Radish has been promoted to reduce compaction, suppress pests, and contribute nitrogen to the cropping system. However, little, if any scientific evidence of these benefits exists for radish. The objectives of this project are to: (1) determine the effects of radish as a cover crop, specifically quantifying the uptake and release of nitrogen (N), and (2) evaluate other soil benefits such as compaction and nematode suppression. The study will be conducted on two grower fields, one in in northwest WI and one in southeast WI. The whole plot treatment will be with or without radish and the split plot treatment will be N rate. The uptake of N will be quantified by measuring the amount of N in radish biomass and the release of N will be measured by soil nitrate analysis at key time points early in the growing season. Compaction will be measured with a portable constant-rate cone penetrometer. Pest nematodes will be counted after isolation by a sieve-washing method. Results will be presented at scientific conferences and as a peer reviewed publication, and will also be extended as an extension publication and a University of Wisconsin-Extension YouTube video. With this greater breadth of knowledge about radish as a cover crop, farmers in the Midwest will be able to make informed decisions about their cropping systems, resulting in improved soil quality and environmental conservation.

The short-term outcomes of this project are to increase our knowledge of how the radish cover crop benefits cropping systems. This project will produce concrete data on the amount of nitrogen taken up by tillage radish, the effect that tillage radish has on corn yield and corn yield response to N fertilizer, as well as the effect that tillage radish has on pest nematodes and soil compaction. This knowledge will be necessary for farmers for deciding whether or not to utilize tillage radish as a cover crop in their own system. From this project, we would be able to create a more comprehensive protocol on how to incorporate tillage radish into a cropping system as a cover crop which would greatly benefit both farmers, crop consultants, seed dealers, and the NRCS.

The long-term outcomes of this project are to increase adoption of cover crops (radish or others) in Wisconsin agroecosystems. If radish proves to be valuable cover crop, it will lead to reduced need for N fertilizer and increase nitrogen use efficiency in these systems. The nematode benefits would decrease need for fungicide applications. The alleviation of compaction would reduce the need for tillage in conventional management systems, as well as benefit conservation and no tillage management systems. Conversely, if radish should not prove to be a worthy cover crop, then farmers and researchers can focus their time and energy on other soil and nutrient conservation methods.

There will be three main outputs of this project: (1) a peer-reviewed publication, (2) a peer-reviewed extension publication, and (3) a YouTube extension video. The peer-reviewed article will be submitted to a journal with an agronomic focus (e.g. Agronomy Journal or Nutrient Cycling in Agroecosystems). The extension article will detail the recommended agronomic usage and effects of radish as a cover crop. The YouTube video will allow growers and extension agents to visualize and see the radish in the field. UW Extension actually has its own YouTube Extension channel where it regularly uploads videos pertaining to its research goals and objectives. A video similar to the one this project will produce has earned over 7000 hits since it was uploaded to the YouTube channel. The extension article could also be a good companion piece published in conjunction with the video. The results of this project will also lead to the development of an established nitrogen credit for radish, most likely published in Nutrient Application Guidelines for Field, Vegetable, and Fruit Crops, a book of guidelines published by UW Madison extension specialists.