Continuous corn concerns
Producers are planting more corn on corn, hoping to take advantage of the ethanol boom. Some are using no-till production systems to improve their soil while conserving water. Without crop rotation, however, no-till corn-on-corn can be challenging if not properly managed, especially with the increased residue levels.
Rather than give up the benefits of no-till, producers can improve their management to make no-till corn on corn less risky. These planting considerations should help make no-till corn on corn more successful.
- Maintain sharp openers.
Double-disk seed furrow openers, if sharp and adjusted properly, can cut through residue better than coulters. The disks should be in good condition and working together as one cutting edge to cut the residue and open the seed-vee.
- Avoid coulters.
Coulters can be used to cut residue, loosen the soil and take some wear and tear away from the seed furrow openers in abrasive soils; however, the tillage they perform may cause air pockets in the seed zone when operated too deep and may overdry the seed zone. If the soil is wet and sticky, the soil disturbed by coulters tends to stick to the depth gauge wheels, affecting planting depth. If the soil is dry and loose, coulters may hairpin residue, rather than cut it.
In these conditions, double disk openers will usually do a better job of cutting residue because they are sharper than coulters and have a slight tearing action as the disks separate. When used, coulters should be set about a quarter inch shallower than planting depth so that the seed furrow opener makes the bottom of the seed-vee. Some companies are moving the coulter a couple of inches to the side of the row to reduce disturbance of the seed zone while providing cutting of the residue so that residue movers can part the residue more effectively.
- Don't hairpin residue.
If hairpinning is a problem, plant deeper as the cutting angle of the leading edge of a double-disk opener or a coulter is directly related to the operating depth. The common 15-inch diameter disk opener cuts residue the best when operated about two to three inches deep. Planting shallower results in hairpinning as the openers are pushing downward on the residue rather than cutting it while moving forward. Sharp cutting edges are a must.
- Do you need residue movers?
Consider spoked residue movers on the planter to warm poorly drained soils by parting the residue or to "even up" the residue. If some of the row has residue cover and some does not, emergence will not be very uniform as there will be differences in soil moisture and soil temperature. Spoked residue movers can remove the thicker layers of residue to make the surface more uniform, but care should be taken not to move any soil.
Floating residue movers with depth bands help keep the surface more uniform, reducing soil movement. However, if the residue cover is already uniform, such as in long-term no-till, residue movers can do more harm than good. In these cases, residue which is detached and moved out of the row at planting time may later blow or wash back over the row. This makes the surface less uniform resulting in less uniform emergence. Emerging corn may leaf out under the residue, again making the stands less uniform.