Tillage--turning the soil to control for weeds and pests and to
prepare for seeding--has long been part of crop farming. However,
intensive soil tillage can increase the likelihood of soil erosion,
nutrient runoff into nearby waterways, and the release of
greenhouse gases into the atmosphere. A reduction in how
often or how intensively cropland is tilled enables the soil to
retain more organic matter, which leaves the soil less susceptible
to wind and water erosion and helps store, or "sequester,"
carbon.
Farmers have choices for how they prepare the soil; reduce weed
growth; incorporate fertilizer, manure and organic matter into the
soil; and seed their crops, including the number of tillage
operations and tillage depth. In general, the less the soil
is disturbed the more organic matter it retains and the less it
erodes. No-till is generally the least intensive form of
tillage; no-till operations accounted for an estimated 35 percent
of U.S. cropland planted to eight major crops in 2009. The
crops--barley, corn, cotton, oats, rice, sorghum, soybeans, and
wheat--constituted 94 percent of total U.S. planted acreage in
2009. Furthermore, the use of no-till increased over time for corn,
cotton, soybeans, and rice, the crops for which the Agricultural
Resource Management Survey (ARMS) data were sufficient to
calculate a trend.
No-till adoption varied substantially across crops, however,
even for those that have generally similar production practices.
For example, land planted to barley had roughly twice the
percentage of no-till (27 percent in 2003) as land planted to oats
(14 percent in 2005).