Land-use effects on soil organic matter and related soil properties in a mixed agricultural–forest landscape of central Wisconsin, USA

Abstract

Soil organic matter (SOM) influences a wide range of ecosystem processes, including nutrient cycling, water movement, plant productivity, and biodiversity. In agricultural landscapes, adjacent land uses often differ in SOM contents and related soil properties, such as soil organic carbon (SOC) stocks, but the direction and magnitude of these effects are inconsistent across studies. We assessed how land uses differed in SOM and related properties in a representative US Midwest agricultural–forest landscape to support land-use and management decisions by local landowners and producers. We measured SOM, bulk density (Db), root biomass, and pH, and estimated SOC stocks, in a Typic Hapludalf under four adjacent land uses (permanent forest, pasture, restored prairie on former pasture, and spruce plantation on former pasture). Surface SOM concentrations and stocks were higher under permanent forest (89 g kg⁻¹ and 85 Mg ha⁻¹, respectively) and pasture (63 g kg⁻¹ and 81 Mg ha⁻¹, respectively) than under restored prairie (49 g kg⁻¹ and 58 Mg ha⁻¹, respectively) and spruce plantation (46 g kg⁻¹ and 46 Mg ha⁻¹, respectively). Land uses also differed in Db, root biomass, and pH, with permanent forest and spruce plantation soils having generally lower Db, more root biomass, and more acidic pH than pasture and restored prairie soils. Specific statistically significant differences depended upon depth in the soil profile. Overall, our results suggest that each land use differentially impacts a unique set of soil properties, precluding any single explanation or management recommendation aimed at improving soil health as a whole.