Long-Term Tillage and Crop Rotation Impacts on a Northern Great Plainsmollisol

Abstract

Soil properties can be altered by tillage and rotation, however, these effects cannot be detected in short-term studies. This study was conducted to assess the long-term (14 years) tillage and rotation impacts on selected soil surface properties. A long-term experimental site comprised of two tillage systems [no tillage (NT) and conventional tillage (CT)], and three crop rotations [corn (Zeamays)-soybean (Glycinemax), corn-soybean-wheat (Triticumaestivum), and corn-soybean-wheat-alfalfa (Medicagosativa)] were used for the present analysis. Surface (0-15 cm) soil samples were collected every year from 1991 through 2004 and analyzed for soil organic matter (SOM), available P, available K, and nitrate (NO3E‰-N). Results indicated that SOM concentration (averaged across all years) under NT (37 g kg-1) was significantly higher compared to that of CT (36 g kg-1). However, overall crop rotation did not impact SOM. Soil P concentration under NT (208 mg kg-1) was significantly higher (8.3%) than that of CT (191 mg kg-1). Available P concentration was the highest in the 2-year-rotation, intermediate in the 3-year-rotation, and lowest in the 4-year-rotation. Tillage system did not significantly impact NO3 - concentration; nonetheless, its concentration was the highest in the 4-year-rotation followed by the 3-year-rotation, and the lowest was in the 2-year-rotation. The available K concentration under NT was not significantly different from that under CT; however, its concentration under the 2-year-rotation (340 mg kg-1) was significantly lower than those under the other two rotations. This 14-year tillage and rotation study had minimal impact on surface soil properties at this location.