In test plots of cotton and peanuts at Tifton, Ga., conservation tillage limited rainfall runoff to less than 10 percent. In some cases, conservation-tillage increased water infiltration into soil by up to 50 percent, compared to conventional-tillage. Conventional plots also released five times more soil and rainfall runoff than conservation-tillage plots, making a strong case for conservation-tillage. Water that washes away from fields can carry soil sediment, nutrients and pesticides to streams and lakes.
The research, led by soil scientist Clint Truman and hydraulic engineer David Bosch at the ARS Southeast Watershed Research Laboratory in Tifton, indicates that a type of conservation-tillage called strip-till not only reduces runoff, but increases water infiltration and appears to improve soil quality.
In strip-till fields, narrow rows, four to six inches wide, are made for planting seed into the previous year's plant- and cover-crop residue.
Plant residues reduce water evaporation from the field and intercept raindrops from impacting directly on the soil surface, decreasing soil movement and cutting down on rain washing away pesticides and nutrients from a field. With conventional-tillage systems, old plant residues are often removed or incorporated into the soil.
Southeastern soils have been intensively cropped, tend to be drought-prone, and are susceptible to erosion. While rainfall registers about 50 inches per year, growers often have to irrigate to keep crops alive during extended drought periods. Producers in this region face a major problem: maintaining crop yields and water use efficiency while addressing soil and water quality concerns associated with sediment, fertilizer and pesticide losses to off-site areas.
ARS is the U.S. Department of Agriculture's chief scientific research agency.