Assessing soil resilience across an agricultural land retirement chronosequence

Abstract

Reestablishment of perennial vegetation can improve soil conditions on intensively cultivated lands, but the timeframe required to recover uncultivated soil quality is not well understood. This study aimed to measure the recovery of soil physical (bulk density, aggregate stability, and water infiltration rate), biological (total microbial biomass and soil respiration), and chemical (surface soil organic carbon [SOC]) parameters across a 30-year land retirement chronosequence. Soil parameters on lands retired under long- and short-term Conservation Reserve Program (CRP) enrollment periods were compared to undisturbed and actively cropped lands, and chronofunctions were utilized to estimate the time required to achieve uncultivated soil quality. Results showed that short-term enrollment was not sufficient to restore any parameters to uncultivated quality, although bulk density, water infiltration, soil respiration, and total organic carbon (C) levels generally trended toward the undisturbed condition. No significant differences between the uncultivated and 30-year CRP enrollment for aggregate stability and total microbial biomass suggests uncultivated soil quality was restored within 30 years of land retirement. Based on chronofunction analysis, an estimated period of 53 years would be necessary to return bulk density and soil respiration to undisturbed quality on retired land. Water infiltration and SOC had the longest predicted recovery time of 75 and 128 years, respectively. These results suggest soil properties recover at varying rates once retired into perennial grassland systems, and long-term land retirement is necessary to restore soil properties to precultivation condition and maintain high quality soils capable of providing key ecosystem services.