Combining alternating cover crop strips, living mulches and strip tillage for effective weed and nutrient management in organic sweet corn production

Graduate Student Final Report – Ceres Trust Research Grant

Graduate Student: Carolyn Lowry

Major Professor: Dr. Daniel Brainard, Michigan State University Department of Horticulture

Summary:

N deficiency and weed competition are the two greatest limitations to achieving maximum yields in organic systems. Increasing the synchrony between soil nitrogen (N) availability and crop demand could potentially decrease fertilizer costs, N losses to the environment, as well as weed emergence and vigor.

The goal of this project is to evaluate whether tillage and organic nutrient amendments can be more effectively utilized to improve N and weed management in organic vegetable systems through a combination of segregated cover crop strips and strip tillage. Strip-tillage is a form of conservation tillage that isolates soil tillage to narrow strips directly in row with crop establishment. Tillage in the in-row strip incorporates residue to supply rapid nutrient release, a fine seedbed, and rooting environment beneficial to crop establishment.

Cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) are commonly used winter cover crops in northern climates, often planted in a uniform mixture. An alternative to this planting arrangement is a stripped intercropping of rye and vetch: with vetch planted in strips directly in line with future sweet corn rows (IR) and rye is planted in the between row zone (BR). When combined with strip tillage, the N supplying vetch is incorporated prior to sweet corn planting, and we hypothesized that sweet corn N uptake efficiency would increase due to the concentration of the N rich vetch reside within the sweet corn rooting zone. Additionally, by planting hairy vetch within the IR and incorporating it with strip tillage we may reduce the potential for hairy vetch re-growth as a weed during the cropping season. The rye reside in the between-row area gets left on the soil surface to immobilize N, and decrease N and light available to stimulate weed emergence. The objectives of this project were to evaluate the effect of vetch and rye alternating strips and strip-tillage on:

1. Weed suppression and community composition within the in- and between-row environments.

2. Cover crop contribution of N and soil N-dynamics.

3. Yield and quality of organic sweet corn.

4. Soil quality by utilizing short term indicators of changes in soil health.

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