Tilling the soil to prepare a seedbed has been practiced for centuries. The moldboard plow, which was introduced in the mid-1800s, was used until the 1970s by most farmers to invert the soil, leaving the soil surface bare of residues. Because the potential for erosion and sediment loss is greater on residue-free surface soils, primary tillage tools that leave some residue on the soil surface to reduce soil erosion were introduced in the 1960s. Since then many styles and types of chisel plows, including V-rippers, have been developed to prepare a seedbed as well as leave some crop residue on the soil surface. Ridge-till systems, which began in the 1960s, were also upgraded, and now have been joined by strip-till and deep zone-till systems for in-row tillage that leave undisturbed soil and substantial amounts of residue between the rows. Lately, fullwidth coulter systems and rolling harrows have been developed to operate in high residue environments. They cut the residue and disturb the soil surface to facilitate planting and weed control while maintaining substantial residue levels. With improvements in planting equipment and plant genetics, including herbicide and pest resistant crops, these high-residue tillage systems are being used successfully.
The soils and climate of the eastern Minnesota River Basin can present significant challenges to corn and soybean producers who want to reduce tillage greatly. Poorly drained, high clay-content soils dominate the eastern Minnesota River Basin. In addition, this area annually receives an average of 30 to 34” of precipitation. This combination of poor internal drainage and higher rainfall can result in cool and wet soils in the spring, which is the greatest challenge facing corn and soybean producers desiring to greatly reduce tillage. Less tillage results in greater amounts of residue blanketing the soil surface, which keeps the soils even cooler and can delay spring planting. Crop growth tends to be retarded under these conditions, and yields may suffer. This is particularly true for corn following corn but can occur when corn follows other crops, especially where the residue has not been evenly spread after harvest.
However, a significant acreage of more well-drained agroecoregions exists within the Minnesota River Basin. These landscapes have steeper slopes, permitting more runoff, and are generally located near major rivers or in lateral moraine areas. These soils generally do not show pronounced negative effects of dense surface residue on crop growth, but soil erosion is much more prevalent. Thus, within the eastern Minnesota River Basin, a broad range of soils exists where a wide variety of conservation tillage systems can be suitable, depending on the field. In other words, choice of tillage is not a “one size fits all” decision.