Tillage practices have a direct correlation to soil health
Farmers have a direct impact on soil quality through many of their field practices, including tillage.
Many areas, including Michigan, have experienced a heightened sense of awareness of the importance of soil quality. Farmers have a direct impact on soil quality through many of their field practices, including tillage.
Soil erosion from wind and water increases as tillage of a field increases. Though the soil may not move off the field, it will be moved from higher to lower elevations, causing some parts of the field to be less productive.
According to the Michigan State University Extension, compaction is also a common side effect of tillage – at the soil surface, the plow layer and the subsoil. Crusting at the surface happens when unprotected wet soil particles are pounded together to form a thin, dense surface layer. This hard surface inhibits water from infiltrating down through the soil profile. It will also increase the potential for water runoff after rain or snow.
Compaction at the plow layer not only causes problems with production but also makes seedbed preparation more labor-intensive. Compacted soils require a secondary tillage followed by a packing tool to make a good seedbed and ensure a good plant stand. Every pass over the field – for any type of tillage or by other farm tools – can break up soil aggregates and reduce the ability of the soil to hold moisture. Heavily tilled fields may have a good seedbed for planting, but any rainfall after planting may cause the surface to seal, resulting in surface compaction. Some soil at this point will harden, reducing plant viability. Soils will soften when it rains again, but plants will suffer as soon as it dries out.
Subsoil compaction, or plow pan, is compaction below the tilled surface layer. The pressure of tillage equipment pressing on the subsoil can cause this. The pressure of tractor tires on moldboard-plowed furrows also can cause subsoil compaction. The effect of subsoil compaction can be exacerbated when fields are tilled when they’re wet.
Many farmers are addressing the compaction problem by using a minimal tillage system. There are several types of minimal tillage systems with various degrees of soil disturbance. With no-till, the soil is not disturbed during planting and a high amount of crop residue remains on the soil surface. With ridge-till, the seedbed is prepared on ridges. The soil between the ridges is undisturbed, and the residue is left between the ridges. Mulch-till involves a minimal amount of disturbance prior to tillage. Chisel plowing is a common type of mulch-till.
An important part of all of these practices is that residue is left on the field. Michigan State University Extension educator Paul Gross visited several fields throughout IsabellaCounty during the fall of 2012 and measured the amount of residue left after various tillage types. His findings are illustrated in the accompanying photos, which show that limited tillage greatly reduced compaction.
Fall tillage is a common practice on many Michigan farms. Farmers should understand how this and other tillage practices affect their soils and their subsequent crops. The challenge is that no two farming systems are exactly the same, so farmers need to find a way to reduce tillage that will work for their individual farms. Some may need to use more than one tillage practice in their crop rotations. For assistance in determining what tillage system will work for your farm, contact your local MSU Extension crop educator.