Conservation Tillage: Good for Drought and Wet
Years By Sharon
Durham December 5, 2007
Conservation tillage studies by Agricultural Research Service (ARS)
scientists in Georgia indicate that this farming practice carries benefits
beyond drought years, by also reducing runoff and erosion in wet years.
This conservation tillage research began in 1998. Since then, farmers
in Georgia have experienced both drought years and wet yearsthe first
four being drought years. Then, in 2002, conditions moderated, and Georgia
received above-average rainfall in 2003 and 2005. Rainfall was below normal in
2004, 2006 and 2007.
Led by hydraulic engineer
Bosch, environmental chemist
Potter, and soil scientist
Truman at the
Southeast Watershed Research Laboratory in Tifton, Ga., the research
indicates that strip-tilla form of conservation tillagereduces
runoff, increases infiltration and increases water available for crop
The greatest benefit of strip-till occurs during dry years. Strip-till
systems enhance infiltration of rainfall and allow more water to get to plant
roots. Any additional water reaching the plant roots during a dry year benefits
the grower through increased yields and reduced irrigation. Conventional
tillage systems lose more water to surface runoff because there is no
protection on the soil surface, and the soil absorbs the full impact of
raindrops, leading to sealing and compaction of the soil.
In wet years, depending on when rainfall occurs, both conventional and
conservation tillage systems can have adequate plant-available water for crop
growth. However, strip-till systems continue to provide increased infiltration
and reduced runoff, lessening the potential for surface-runoff-related
In the fall and winter, when evaporation and transpiration are low,
infiltrating water often exceeds the soil's capacity to retain it. When
considering all water losses, conventional-till systems lose more water because
of the greater surface runoff.
During wet or dry growing seasons, strip-till benefits Georgia growers
by increasing the amount of rainfall or irrigation water infiltrating the soil
and becoming available to plants.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.