Intensive Tillage Converting Grassland to Cropland Immediately Reduces Soil Microbial Community Size and Organic Carbon

Abstract

Intensive tillage of grassland has negative long-term effects on soil health, but little data exist to understand how quickly this decline occurs. We sampled a commercial field in the semiarid Southern Plains of the United States before and after tilling grassland and compared the results to adjacent row crop and perennial grass fields. Within the first month of tillage, we detected losses of 52% of microbial biomass C (505 to 241 mg kg-1 soil), 33% of organic C (11.6 to 7.78 g kg-1 soil), 30% of total N (1.09 to 0.760 g kg-1 soil) and 64 to 70% of β-glucosidase and phosphodiesterase activities. The rapid decreases in these soil health indicators demonstrate that tillage management decisions are crucial for maintaining soil health if perennial grasses are converted to row cropping.