PETE’S CORNER
With the coming of the ethanol market, many farmers have considered, and are still considering, planting their land to continuous corn. According to UNL Extension specialists and educators, there are several considerations to make when comparing continuous corn versus a corn soybean rotation.
It will come to no one’s surprise that, economically, producers will provide more input costs for planting continuous corn. These inputs include increased nitrogen, insecticide and/or seed cost for a Bt rootworm hybrid, irrigation where available, and potentially a fungicide treatment. As an example, nitrogen prices certainly will not be going down in the next year or so and will most likely go up.
Another consideration is equipment needs and labor. A corn/soybean rotation spreads out the planting and harvest season so one may be able to use smaller equipment and/or less labor. There are a lot more bushels to handle in a continuous corn rotation versus a corn/soybean rotation. Drying costs for continuous corn versus a corn/soybean rotation also may be affected. One could be harvesting soybeans while the corn dries down.
A long-term tillage study conducted at the South Central Agricultural Laboratory near Clay Center compared yields from continuous corn and a corn/soybean rotation in disk, ridge and slot-planted systems. The data shows increased corn yields from 3.4 to 9.1bushels per acre when followed by soybeans in all systems.
When it comes to pest considerations, rotation disrupts most pest cycles. Insects such as corn rootworm often do not survive corn/soybean rotations in Nebraska. Newer technologies such as Bt corn rootworm traits are one way that producers can manage corn rootworm in a continuous corn system. Soil insecticides also can be used. Pathogens causing diseases such as gray leaf spot, anthracnose and numerous stalk rots survive in corn debris.
Rotation to another crop can reduce the severity of these diseases the next time corn is planted. However, rotation will not completely destroy these pathogens. Tillage will bury the residue, destroying the pathogens. However, the benefits of conservation tillage, such as increased soil moisture and improved soil structure, may outweigh the benefits of tillage. Management strategies such as planting more resistant hybrids and the use of fungicides can replace or be used in addition to crop rotation and tillage.
Prices and production costs at the South Central Agricultural Laboratory from 1985 to 2004 showed a $60 per acre advantage to the corn/soybean rotation versus continuous corn. However, the current high price of corn, coupled with high yields, may offset additional input costs for continuous corn. Crop prices, yields, production costs, insects and diseases will all affect which crop rotation will be the most profitable in the future.
In Washington County, which is primarily dryland, consideration also needs to be made regarding the timeliness of rains. In 2007, the rains were in August and September making for an excellent soybean crop. Although corn yields were good, they were not as good as in the past as I understand. In some years in can be just the opposite as corn is benefitted by the rains and soybeans do not benefit as much. By using a corn/soybean rotation, the farmer will spread out the weather risks over two crops rather than just one.
