Monday, November 13, 2006

Environmental Influences on Conservation Tillage Adoption in the Central US.

Amy Swan1, Stephen Ogle1, Robin M. Reich2, and Keith H. Paustian3. (1) Natural Resource Ecology Laboratory, 1231 East Dr, Fort Collins, CO 80523, (2) Dept of Forest, Rangeland and Watershed Stewardship, Colorado State Univ, 1472 Campus Delivery, Fort Collins, CO 80523, (3) Natural Resource Ecology Laboratory, Colorado State Univ, 1231 East Dr, Fort Collins, CO 80523

Conservation tillage provides many benefits to soil including reduced soil erosion, increased soil fertility, increased soil moisture and improved soil physical properties.  However conservation tillage is not widely adopted by producers, possibly due to loss of crop yields following adoption.  A literature review of long-term tillage trials was conducted to compare crop yields from conventional and conservation tillage systems across a wide range of environmental conditions.  On average, a change from full tillage to no-till reduced crop grain yields by 0.0448 ± 0.874 metric tonnes dry matter/ha.  Given the magnitude of variance, the mean difference in crop yields was not significant between tillage types. To further evaluate differences in yields, a statistical model was developed to compare differences among crop types, climatic conditions, years since tillage conversion and soil texture.  We found a significant reduction in yields of 2.7 metric tonnes dry matter/ha for no-till adoption in regions with high annual precipitation and low annual mean temperatures.  This finding concurs with results from previous tillage field experiments that observed yield declines in colder, wetter climates. Results were mapped for the 21 states in the Central US and compared to historical patterns of no-till adoption using data from the Conservation Technology Information Center.  Findings suggest that environmental constraints have limited adoption of conservation tillage in the northeastern portion of the central US farmland region.

Handout (.pdf format, 646.0 kb)