Cover Cropping and Residue Management for Weed Suppression, Soil Fertility and Organic Crop Production

Cover Cropping and Residue Management for Weed Suppression, Soil Fertility and Organic Crop Production

Summary

Cover crop plots were established at the Upper Piedmont Research Station in Reidsville, NC in the fall of 2002. Dry weather at planting followed by extremely wet weather at the seedling stage impacted cover crop stand. Percent of canopy coverage in each plot was determined by plot transects in December and March of 2002. Percent coverage ranged from 8 to 52% in December of 2002 and from 15 to 90% in March of 2003. Cover crops grew until mid-May of 2003, and biomass samples from 0.5 m2 quadrants were measured and submitted for N analysis. Crimson- and subterranean-clover treatments were strip-tilled and edamame seeded with a two-row vacuum seeder. The clover was allowed to reseed between the edamame rows. The five rye treatments were strip-tilled, rolled, flail-mowed, disked, and treated with glyphosate herbicide, respectively, and seeded to edamame soybeans. Seeding was “no-till” in rolled, mowed, and herbicide treatments. At harvest, edamame and weed biomass was determined in 0.5 m2 quadrants. Soybean yields were low due to high weed pressure in all treatments. After harvest, all plots were flail-mowed. Plots were mowed again in August. In early October the rye treatments were resown to rye alone. A decision was made not to include crimson clover in with the rye, but to provide N in the spring from animal sources. The crimson and subterranean clover treatments regenerated enough cover from seed spilled by the previous year’s cover crops. Organic corn for milling will be planted in early May. Heirloom variety seed will be donated by Anson Mills.

Objectives/Performance Targets

1. Investigate the weed suppression of crimson clover, rye, and crimson clover/rye biculture cover crops prior to the establishment of principal crops and in the subsequent vegetable soybean and corn crops.
2. Evaluate techniques for mechanically killing cover crops as alternatives to use of herbicides.
3. Investigate the reseeding capacity of crimson clover left to mature in a strip crop tillage system.
4. Investigate the N contribution of a cover crop biculture (crimson clover/rye) in a cereal rye-edamame-crimson clover/rye biculture-corn rotation.
5. Characterize N cycling in a cereal rye-vegetable soybean-crimson clover/rye biculture-corn rotation.
6. Publish results, demonstrate successful production practices to growers, produce written production guidelines, and discuss results at professional and county meetings, conferences, and field days.

Accomplishments/Milestones

We harvested edamame soybean following cover crop treatments. Crimson clover and subterranean clover plots successfully reseeded themselves from plants left to mature between edamame rows. Rye treatments were reseed with a 10′ drill in the fall of 2003. Weed and crop (cover and edamame) biomass was determined two times during 2003. Yield of edamame was also determined.

Impacts and Contributions/Outcomes

Weed growth was only minimally suppressed by cover crops and cover crop residues, and yields of edamame soybean were apparently suppressed relative to full tillage and herbicide treatments.

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