Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2003
Publication Date: 6/1/2004
Citation: Needleman, B.N., Gburek, W.J., Petersen, G.W., Sharpley, A.N., Kleinman, P.J. 2004. Surface runoff along two agricultural hillslopes with contrasting soils. Soil Science Society of America Journal. 68:914-923. Interpretive Summary: Eutrophication is the biological enrichment of surface waters triggered by nutrients such as phosphorus. Due to eutrophication problems that are common in many parts of the U.S. and the world, extensive efforts are underway to minimize nutrient runoff from agricultural fields. A key need is to identify fields that are prone to runoff. In this study, runoff was monitored from fields located in Pennsylvania's Valley and Ridge Province. Differences in the tendency for a field to generate runoff were linked to underlying soil properties. Well drained soils formed in relatively loose materials directly derived from weathering of the underlying bedrock produced runoff infrequently, requiring large rainstorms for runoff to occur. Poorly drained soils with dense sub-surface horizons that formed in gravity-transported materials filling valley bottoms frequently produced runoff, even under small rain events. These differences indicate that soil survey information can be used to identify fields and sites within fields that are prone to runoff and point to the need to develop soil-specific strategies for water quality protection.
Technical Abstract: The targeting of critical surface runoff producing zones should account for the influence of subsurface soil characteristics. In this study we assessed the runoff response of contrasting colluvial and residual soils. The study was conducted along two hillslopes within a 39.5-ha mixed land use watershed in Pennsylvania. Six sites (4 colluvial, 2 residual) were monitored for runoff, hydraulic head, water table depth, and soil water content. A total of 111 rainfall events were monitored during the periods of July-Dec. 2000, April-Dec. 2001, and April-Dec. 2002. Two high intensity (5-min peak > 8 cm hr-1) events had return periods of 2.5 and 4 years. The colluvial soils are somewhat poorly and moderately well drained with fragipans and high clay content (37-44%) argillic horizons (Fine, mixed, semiactive, mesic Aquic Fragiudalfs); the residual soils are well drained with moderate clay content (24%) argillic horizons (Fine-loamy, mixed, semiactive, mesic Typic Hapludults). Across all events, overall runoff yields averaged 2.4% from the four colluvial sites and 0.01% from the two residual sites. The two colluvial sites with the greatest runoff production were located at the base of a primarily colluvial hillslope. The largest events at these sites occurred during periods of surface saturation (soil surface to a depth of at least 30 cm). These results suggest that non-winter P management for these residual soils should focus on rare, large events. Nutrient management planning could be improved if runoff estimation methods were to better integrate information on subsurface and upslope soil hydrologic properties.