Caption title. At head of title: Project summary. Distributed to depository libraries in microfiche. "June 1983." "EPA/600-S2-82-022."

The objective of this study was to evaluate the mechanisms and effectiveness of vegetated buffer zones or borderland areas in reducing pollutional impact of rainfall runoff from sites used for land application of livestock or poultry manure. The effect of grass buffer-zone length on the reduction of pollutant concentration and mass in runoff from land application areas was studied over a nine-month period for several different buffer-area length/ application-area length ratios. Also, one-dimensional mathematical models were developed to investigate the effects of dilution and infiltration. The field study consisted of measuring rainfall runoff pollutions! characteristics at various distances downslope from areas where caged-layer poultry manure was applied regularly. Evaluation of nutrients and solids in runoff samples revealed that grass buffer zones effectively reduced the pollutions! concentrations, and that the amount of reduction increased with an increase in the ratio of buffer-area length to application-area length. The model and experimental results suggest that infiltration is the major factor affecting buffer-zone length. Soils having greater infiltration rates will require shorter buffer lengths to obtain the same percent reduction of pollution potential. The results also indicate that required buffer-area length is a function of the application-area length. Application areas having longer slopes require longer buffer lengths to obtain the same percent reduction of the pollution potential. The pollution potential of the application area likewise affects buffer length because a greater percent reduction is required to obtain a desired water quality standard if the application area runoff pollution potential is larger.