CHARACTERIZING THE SURFACE PROPERTIES OF SOILS AT VARYING LANDSCAPE POSITIONS IN THE OZARK HIGHLANDS.

Abstract

Surface runoff of nutrients after land application of animal manures is influenced by climate, physical and chemical properties of the soil, and land use. The objective of this study was to characterize the surface soil properties from a riparian forest to an adjacent ridge top at a site in the Ozark Highlands. Sampling transects (60 m long) were established in five soil map units, 7.6-cm-diameter × 10-cm-deep cores extracted at 3-m intervals, and samples analyzed to determine relevant soil physical and chemical properties. Ponded infiltration measurements were also completed on four of the transects. Soil test phosphorus and phosphorus saturation ranged from 10 to 31.4 mg kg−1 and 9.1 to 18.4%, respectively, and reflect the recent history of limited poultry litter or fertilizer application. Soil samples from each transect had similar average silt content (range = 67.2-73.9%), but the soil in the riparian forest (Razort silt loam) had more clay and significantly less sand and coarse fragments. The Razort soil also had a higher cation exchange capacity (CEC) (20.7 cmol kg−1) and infiltration rate (5.29 cm h−1). Trends in clay content, infiltration rate, and CEC suggest that the riparian forest and adjacent alluvial pasture may act as nutrient sinks in this landscape. Results of this study will be combined with grazing management and hydrologic analyses to develop best management practices for poultry litter applications and to provide baseline data for the assessment of long-term effects of litter application on soil properties.