For the past six years, USDA ag researchers have been keeping sharp eyes on 4.6 acres of Georgia farm land. They wanted to see how much water ran off strip-tilled plots compared to fields where conventional tillage practices were used.

In the first three years of the study, surface runoff from conventional-till plots was considerably greater than that from the strip-till plots. Strip-till areas showed that only 3 to 9 percent of rain ran off the surface, while in the conventionally tilled plots 12 to 22 percent of the rain was lost to runoff. However, during peak periods of heavy rainfall, surface runoff from the conventional-till plots was up to five times greater than that from strip-till plots.

This study only confirms what many farmers already know: it's smart farm economics to protect your fields from water runoff. Leaving some residue on the surface retains valuable water, especially useful in seasons of drought, and it also prevents topsoil from being carried away.

The study site was 4.6 acres of land on the University of Georgia Gibbs Farm near Tifton. The area was divided into six half-acre plots, with a seventh one-acre plot set aside for companion rainfall-simulation studies. A crop rotation of cotton and peanuts, common to this area of the Southeast, was used.

Another plus for strip-till systems was that soil loss from these plots was consistently lower than from the conventional-till plots. In the fall of 2000, soil loss from conventional-till plots was more than four times that from the strip-till areas, increasing to five times by the spring of 2001. "This data shows that strip-till systems have the potential to substantially decrease sediment loss from fields," said David Bosch, a hydraulic engineer who worked on the project.

Southeastern soils have been intensively cropped for years and are prone to both drought and heavy rainfalls that cause damaging erosion. While rainfall in this area averages about 50 inches a year, growers must nevertheless be prepared to irrigate during extended periods of drought at the peak of the growing season.

These conditions present growers with major problems in maintaining crop yields and water-use efficiency while also trying to keep sediment, fertilizers, and pesticides out of area rivers.

Strip-till differs from no-till because a narrow row in which crops are planted, four to six inches wide, is tilled between crop residue on the soil's surface. Plant residue left on the ground acts as a barrier to water evaporation from the field. It also keeps raindrops from falling directly on the soil, thereby decreasing movement of soil, pesticides, and nutrients off the field.

With conventional tillage, nearly all plant material is either removed or incorporated into the soil, leaving it exposed to rain and erosion.

The research concluded that strip-till reduces runoff and erosion, increases water infiltrating the soil, and improves soil quality. "This research could conceivably help producers increase water-use efficiency and reduce irrigation. By doing so farmers could increase the profit margin while maintaining water supplies and minimizing off-site environmental contamination," said soil scientist Clint Truman.