EVALUATION OF SOIL PHYSICAL AND CHEMICAL QUALITY IN RESPONSE TO PRESCRIBED SHEEP GRAZING

Grazing effects on soil quality are enigmatic due to the wide variety of grazing methods (e.g., continuous, rotational, and strip grazing) and the number of variables (e.g., grazing animal and vegetation type) at play. Prescribed sheep grazing has gained popularity in recent years in part due to the possible benefits ranging from improved nutrient availability and water quality to greenhouse gas mitigation. However, the spatial and temporal influence of prescribed sheep grazing on soil nutrients and physical properties is not well documented at small regional scales. This investigation sought to evaluate the physical and chemical quality of soil in response to prescribed sheep grazing on an area of redeveloped land in Southwest Michigan, with particular attention to variations across soil depths. A systematic sampling approach aligned with USDA protocols, this study began to measure the effects of prescribed grazing on soil nutrients (NPK) and physical properties before and after grazing over a grazing season. Key parameters measured included soil pH, conductivity, bulk density, soil moisture, infiltration rate, and carbon and nitrogen elemental composition. Collection and analysis of soil cores indicate predominantly sandy or clay loam soil in the first 0-11 inches, transitioning sharply to clay-rich soil below, likely a result of prior tilling. Soil cores were collected from five locations to a depth of 60 cm broken into four segments prior to the current grazing season with subsequent repeat sampling occurring over the course of the grazing season. Additional samples were taken for chemical analysis and bulk density measurement. Initial results indicated that prescribed grazing influences nutrient availability and infiltration in the upper 6cm. Further analysis over the remainder of the season will clarify potential benefits. To date, postgrazing shows evidence of enhanced ecosystem resilience. Subsequent seasonal grazing events will likely continue improving soil nutrients and health.