by Jim Lopshire, Paulding County
Cover crops are an effective tool to reduce soil erosion and increase nutrient recycling on farmlands, thereby also decreasing the soil and nutrient loads entering lakes and waterways. Cover crops can have numerous other benefits including improvement of soil quality, pest management, fertility management, water availability, landscape diversification, and wildlife habitat.
Proper choice and management of cover crops are important in maximizing the benefits and reducing potential problems. Characteristics important for cover crop selection include life cycle, seeding date and rate, winter hardiness, nitrogen fixation or scavenging ability, feed or forage value, and establishment costs. There is no single cover crop or system that will provide all these benefits. Therefore, experimentation may be necessary before producers decide on a suitable cover crop for an individual system.
Several plant species have been successfully used as cover crops in Ohio. They are best categorized by lifecycle, because the type of lifecycle dictates the nature of their vegetative growth and hence value as a cover crop for a given situation.
Annuals complete their vegetative growth in one growing season, so residue production is limited by the period available for growth from planting to frost or freeze, and environmental conditions during that time. This lifecycle offers the advantage of not having to kill the cover the following spring, but can be a problem if not enough residue is produced in fall. Annuals can produce ground cover very rapidly with favorable growing conditions. Examples of annuals successfully used cover crops in Paulding County include oats and oilseed radish.
Winter annuals such as cereal or annual rye are planted in fall of one year and complete their vegetative growth the following season. This offers the advantage of residue production in the fall, as well as spring after the soil thaws. Often winter annuals produce insufficient growth in fall, depending on when planted, to be effective cover. However, spring growth can provide substantial vegetative growth and root development. An obvious disadvantage of growth resuming in spring is the need to destroy the cover. Delay in destroying the cover may result in excess soil moisture loss to the detriment of the following crop.
Perennials, comprised of the traditional forage legumes, have lifespans of two or more years. They are of low value as cover crops planted for conservation purposes in late summer, because a combination of slow germination and early growth limits residue production. However, they do offer tremendous potential as nitrogen supplying green manures when seeded with small grains in the year before corn, where they have sufficient time to grow and fix atmospheric nitrogen.
Various cover crops serve a variety of purposes. Producers must select the right species for their particular situation. The Midwest Cover Crop Council (MCCC) has created a “Cover Crop Decision Tool” to assist farmers in selecting cover crops for their operation. The web-based system consolidates cover crop information by state to help farmers make cover crop selections at the county level. Go to the following web site http://www.mccc.msu.edu/SelectorTool/2011CCSelectorTool.pdf and you will find instructions for using the decision tool and the decision tool selector.