Hairy vetch, winter rye, Juliet, fungi and a Pink Beauty

Tomato trial puts cover crops, mycorrhizae inoculation to the test.

By Alison Grantham and Betsy McCann

Rodale Institute researchers are collaborating with USDA scientist David Douds to use tomatoes to evaluate the role of cover crops and mycorrhizal fungi inoculation in vegetable systems. We have 1440 tomato plants in a test plot just behind our farmstead, soaking up some much-needed sun after lots of late spring rain and cool weather.

The patch consists of three cover crop types: hairy vetch, rye, and a rye-vetch combination. These over-wintering cover crops were rolled with our no-till roller/crimper.

Half the plot is dedicated to crop production, while the other half focuses on Integrated Pest Management elements such as nitrogen availability and cover-crop comparison. Interspersed within the plot are crop-free areas, designed to evaluate the weed pressure in the absence of a crop.

In the ground are the varieties: Juliet, a high-yielding plum tomato and common CSA variety; Pink Beauty, another common CSA variety; and Striped German, a large-fruited, bi-color heirloom.

Half of the tomatoes are inoculated with mycorrhizal fungi to test the value of this process to impact their growth. Mycorrhizae colonies help plants absorb phosphorus, zinc and copper by attaching to root structures, and effectively extend the plant’s root system. Research done by USDA and Rodale scientists has lauded these fungi for their ability to increase crop yields, enhance disease resistance, improve water content, improve soil aggregation, and facilitate carbon sequestration.

The goal of the project is good demonstration and good science. Tomatoes were chosen because of their need for nitrogen, which can be provided through hairy vetch or organic fertilizer—kelp in this case, for the non-legume portions. Differences in cost between the fertilizer and the seed for the hairy vetch are being analyzed to find the most cost-effective combination for farmers to pursue.

Similar projects are taking place at Pennsylvania State University, in State College, Pennsylvania, and at the USDA Agricultural Research Service’s Agricultural Research Center in Beltsville, Maryland.

This study builds upon research done by Dr. Douds, a soil microbiologist with the USDA’s Agricultural Research Service, who has dedicated years to studying the benefits of mycorrhizal fungi. His research projects conducted at the Rodale Institute over the past 20 years have addressed different tillage and agronomic systems’ effects on the presence of mycorrhizae, the relationship between levels of mycorrhizal fungi and crop yields, as well as research into how farmers can devise their own ways to grow and use mycorrhizae inoculants to boost crop resilience in healthy soil systems. (Click here to read more about Dr. Douds' mycorrhizae research.)

Staff and interns are looking forward to sampling the results, after all the data is collected, at the Institute’s annual Heirloom Tomato Tasting at summer’s end.

Alison Grantham is a research and policy associate at the Rodale Institute.

Betsy McCann is a third year doctoral student in agricultural communications at Texas A&M University, serving this summer as a communications intern at the Rodale Institute.