Rapid change in soil properties after converting grasslands to crop production
Jeffrey S. Strock, Jane M. F. Johnson, David Tollefson, Andry Ranaivoson
Abstract
Abstract Changes to land management over the last 150 years, primarily the conversion of perennial grasslands to agricultural production dominated by annual row crops, have greatly changed soil properties and reduced the soil's ability to infiltrate and store water in the soil profile. Direct near‐term response at the time of conversion of an uncultivated remnant prairie to row crops is rare, especially responses that include repeated measurements on the same parcel of land and resampling of soils to a depth of 1 m to document rapid changes in soil organic carbon, nitrogen, and selected soil physical properties related to hydraulic properties. The objective of this research was to measure changes in soil chemical and physical properties after the conversion of perennial grassland to annual row‐crop production. A before‐and‐after approach was used to compare soil properties from a 0.31‐ha field in southwest Minnesota. Cultivation resulted in a negative shift in soil properties. Two years postcultivation, there was an overall reduction in soil organic carbon of 18.6 Mg ha −1 for the 0–1.0 m soil profile. Infiltration rates and soil sorptivity exhibited significant decreases following cultivation. The average decrease in the mean postcultivation infiltration and sorptivity rates were 0.30 mm s −1 and 0.12 mm s −0.5 , respectively. Bulk density increased on average by 0.10 Mg m −3 between 0–0.2 m and 0.14 Mg m −3 between 0.2–1.0 m. This work provided a rare glimpse of the vast shift in soil properties, which occurred when the plow ripped through virgin prairie decades ago during the massive expansion of agriculture.