Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2004
Publication Date: 1/1/2005
Citation: Moffet, C.A., Zartman, R.E., Wester, D.B., and Sosebee, R.E. 2005. Surface biosolids application: Effects on infiltration, erosion, and soil organic carbon in chihuahuan desert grasslands and shrublands. Journal of Environmental Quality. 34:299-311. Interpretive Summary: Since the Ocean Dumping Ban Act of 1988, many municipalities have had to find other methods of dealing with their wastewater treatment solids (biosolids). Application of biosolids as a soil amendment is one way to deal with this issue but the ecological impacts of this procedure have not been adequately determined for arid and semiarid rangelands. We evaluated the effect of biosolids application on infiltration and erosion in Chihuahan desert rangelands and determined that surface application of these materials to the soil reduces runoff and erosion. The degree of these effects depended on soil type, vegetation and biosolids characteristics. These results will help State and Federal agencies design regulations that provide for the beneficial use of biosolids while continuing to protect environmental quality.
Technical Abstract: Surface land application of biosolids is a beneficial use practice whose consequences depend in part on hydrologic effects. Biosolids were surface-applied to square 0.5 m2 plots at 5 rates on each of 3 soil-cover combinations in a Chihuahuan desert grassland and a Chihuahuan desert shrubland. Infiltration and erosion were measured during 2 seasons for 3 biosolids post-application ages. Infiltration was measured during 8 periods of a 30-minute simulated rain. Biosolids application affected infiltration rate, cumulative infiltration and erosion. Infiltration increased with increasing biosolids application rate. Application of biosolids at 90 dry-Mg ha-1 increased terminal infiltration rate by 1.9 to 7.9 cm hr-1, but the typical increase was 3 cm hr-1. Few of the measured differences in infiltration among biosolids application rates could be accounted for with interception losses. Soil erosion was reduced by the application of biosolids. The reduction in erosion depended on the initial erodibility of the site. Typically, the greatest marginal reductions in erosion were achieved at the lower biosolids application rates; the reduction in erosion achieved by increasing the biosolids application rate from 34 to 90 dry-Mg ha-1 was insignificant. Surface application of biosolids has important hydrological consequences in desert grasslands that depend upon the rate of biosolids applied and these consequences are further modified by site characteristics.