Date of this Version
FIELD CROPS G-6, Cropping Practices Revised March 1986, 12,000
Selecting the tillage system best suited to a particular farming situation is an important management decision. Formerly, the traditional system was a moldboard plow operation followed by several secondary tillage operations before planting. This system can be appropriate for poorly drained soils having little or no slope and low erosion potential. However, plowing has several disadvantages . The potential for soil erosion is high on sloping lands, and labor and fuel requirements can be substantially higher than with other tillage and planting systems.
Today, conservation tillage systems are used to reduce preplant tillage operations, thus reducing soil erosion and moisture loss while saving labor and fuel. The label "conservation tillage" represents a broad spectrum of farming methods, and is most often defined by the amount of residue cover remaining on the soil surface. The minimum amount recommended is 20 to 30 percent after planting. Research in Nebraska and other Midwestern states has shown that leaving at least this much residue will reduce erosion by more than 50 percent of that occurring from a cleanly tilled field. To achieve effective erosion control, this minimum residue cover should be maintained during the critical soil erosion period between spring seedbed preparation and crop canopy establishment.
Conservation tillage does not necessarily require new equipment. Most conventional farm implements can be used. For corn, grain sorghum, or wheat residue, one or two passes with a field cultivator, disk, or chisel plow will usually leave more than the 20 percent minimum cover. Additional operations reduce the amount of residue, and thus reduce erosion control. Other tillage and planting systems such as ridge-plant (till-plant) and no till leave even more residue, and thus offer greater erosion control. However, no-till planting is the only method that consistently leaves the minimum surface cover in the more fragile and less abundant soybean residue.
No single tillage system is best for all situations at all times. Selecting the best tillage system for a particular soil and cropping situation requires matching the operation to the crop sequence, topography, and soil type. Rotating systems to coincide with crop rotations often provides an excellent combination. For example, a no till system could follow soybeans while a chisel or disk system might follow corn. This tillage rotation provides the best erosion control following soybeans, and provides an opportunity for some tillage in the less fragile and more abundant corn residue.