When shifting from a corn-soybean rotation to growing corn after corn, there are several equipment considerations. They include residue spreading, possible use of tillage implements, planter operation, and adjustments in the harvesting system. Following is a general overview.
Heavy residue amounts from good corn production generally have little effect on soybeans planted the next spring. Planting corn into corn residue, however, can be more challenging with potential effects on corn seed placement, early growth, and development. Residue management starts with spreading residue behind the combine as uniformly as possible. Only the top portion of the stalk goes through the combine, but when using the chopper, drive and blades should be well maintained and spreading vanes (if present) adjusted. If a chaff spreader is used behind the cleaning shoe, vanes on discs should be maintained and angled appropriately and the drive maintained for appropriate speed. A decision on whether to chop stalks attached to the ground often depends on if they will interfere with subsequent tillage equipment.
In warm and dry soils, tillage seems to have minor effects on yields. In wetter and colder soils, however, continuous corn yields often increase somewhat with tillage. Implement selection will depend on tillage depth and the ability of residue to flow through the implement without plugging as well as environmental (i.e., erosion) concerns. Large diameter discs are commonly used for cutting and sizing stalks. A disc implement may be considered for shallow tillage. If deep tillage is required, combination subsoiler implements with a front gang of discs, subsoiler shanks, a rolling rear leveling device, and spacious clearance between these may be used. Strip tillage (i.e., tilling only in the row zone) may gain much of the benefit in cold and wet soils without excessive tillage.
Increased residue at or near the surface, particularly in minimum- or no-till systems, puts a premium on maintenance and operation of soil-engaging parts of the planter (i.e., seed opener, front attachments, and closing system). Because ability to cut through residue at or near the surface is important, the seed opener should be maintained to present a very narrow profile at the soil entry point. As opener edges wear, disc blades need to be repositioned to maintain this narrow profile. Row cleaners, adjusted to move primarily residue but little soil, help corn to get a more uniform early start, particularly in tillage systems with high levels of surface residue. Remember to adjust down pressure of closing wheels or discs for good seed-to-soil contact. Make sure the planter frame is leveled, otherwise it will be virtually impossible to maintain proper height of front attachments or correct closing wheel pressure.
Hard soil conditions or uneven residue piles on the surface can cause shallow seed depth. Check to ensure that depth-gauge wheels on row units are in firm contact with the soil and that surface residue is either spread evenly or pushed away from the row zone by row cleaners.
Depending on environmental conditions, there may be greater potential for disease on corn kernels during harvest when corn is raised following corn. Generation of further disease and storability are affected by excessive damage to the seed coat. Use the lowest combine rotor or cylinder speed to maintain adequate threshing without excessive harvest machine loss.
Assess capacity of harvest equipment, grain transport from the field, drying, and storage. Acres moved from soybean to corn production produce roughly three times the volume of material that must be removed from the field. If field dry-down is not sufficient, corn acres place an additional load on the drying system.
Mark Hanna is an extension agricultural engineer in agricultural and biosystems engineering with responsibilities in field machinery.
This article originally appeared on pages 24-25 of the IC-498 (1) -- February 12, 2007 issue.