The effects of tallgrass prairie restoration on soil quality indicators

Soil quality refers to the ability of a soil to perform functions critical to the ecosystem. Native prairies are renowned for the richness of their soils, which have excellent soil structure and are typically very high in organic content, nutrients, and microbial biomass. In this study, soils from the top 5 cm of 3 prairie restorations of varying ages and community structures were compared with a nearby undisturbed prairie remnant and an agricultural field in terms of soil physical, chemical, and microbial properties. Water-holding capacity, soil moisture, soil organic matter, organic carbon, organic nitrogen, organic sulfur, and viable microbial biomass were significantly greater in the prairie remnant, as well as in the 2 long-term (21 to 24 y) prairie restorations, compared with the agricultural field and the restoration that was begun more recently (7 y prior to sampling). Nitrate-nitrogen and soil bulk density were significantly greater in the agricultural and recent restoration sites. In most cases, the values for the soil quality indicators in the restoration sites were intermediate between those of the virgin prairie and the agricultural sites. Samples could be assigned to the correct site by a multivariable discriminant analysis using these soil characteristics, with the exception that the agricultural samples were sometimes classified incorrectly by the computer model as coming from the recent restoration site. These findings suggest that prairie restorations can lead to improved quality of surface soils over a period of decades.