Planting in Cover Crop Residue

Authors: Kornecki, Ted; Balkcom, Kipling

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 3/2/2017
Publication Date: 3/19/2020
Citation: Kornecki, T.S., Balkcom, K.S. 2020. Cover Crop Management. In: Bergtold, J., Sailus, M., editors. Conservation tillage systems in the Southeast: Production, profitability, and stewardship. SARE Handbook Series Book 15. Sustainable Agriculture Network. p. 119-132.

Interpretive Summary: In conservation tillage systems, cash crop seeds or transplants are placed in the soil through cover crop residues on the soil surface. The residue inhibits weed emergence, increases rainfall infiltration, conserves soil moisture, keeps the soil cool and prevents the soil erosion and nutrient loss associated with rainfall runoff. Soil compaction is reduced because the grower makes fewer passes over the field and can use lighter equipment. Cover crops are terminated at least three weeks before cash crop planting to avoid competition with the cash crop for water and nutrients. In this chapter, equipment and strategies for rolling/crimping cover crops are described by ARS scientists located in Auburn, AL. Equipment modifications are detailed for combining herbicide application and rolling/crimping in one pass. Selection of equipment for planting field crops and vegetable crops through residue is described. Planting equipment modifications are discussed including row cleaners, shanks, closing wheels and seed firmers. The information provided in this chapter for the book titled “Conservation Tillage Systems in the Southeast: Production, Profitability, and Sustainability” will be a valuable resource for producers, agricultural engineers, scientists, graduate students, and other agricultural professionals needing information on how to properly manage cover crops to maximize their benefits with respect to farm operations, research programs, or general agricultural knowledge.

Technical Abstract: In the United States, cover crops are commonly terminated with herbicides, usually glyphosate. Spraying is fast, effective and inexpensive. Herbicide termination provides the flexibility to kill the cover crop in any growth stage. Spraying can be delayed to maximize cover crop biomass and gain the greatest benefit. When tall cover crops such as cereal rye, sudan grass or sunn hemp are terminated with herbicides, they fall in different directions. This results in seed or transplant placement problems, accumulation of residue on planting units, and frequent stops to clean the equipment. Termination methods include rolling/crimping, herbicide application, mowing, burning and incorporation. Rolling/crimping results in a mat of cover crop residue on the soil surface. Plants are flattened by the roller and crimped at regular intervals in one pass. The objective is to discourage root growth by injuring the plant without cutting the stem. All the plants fall in the same direction, which reduces residue accumulation on equipment and improves seed and transplant placement. Roll/crimp most cover crops when they are in the reproductive stage: for cereal grains, early milk to soft dough; for clovers, mid-bloom; and for vetch, early bloom. For other cover crops like cowpeas, sorghum or sunn hemp, there is not much research available. Roll/crimp these cover crops when they reach maturity. Allow tall growing covers like sunn hemp and sorghum to reach appropriate height before rolling. When selecting the termination date, consider the goal of maximizing biomass production as well as the needs of the following crop.