The effects of agricultural land use patterns on pollutant runoff from watersheds: rangeland/pastureland and row cropping

Abstract

Much attention is being focused on water quality in rivers, lakes and streams. One of the contributors of pollution to rivers, lakes and streams is runoff from agriculture in the form of nutrients, pesticides and suspended solids. This study was designed to look at the amount of these substances produced in subwatersheds from corn, grain sorghum and cotton farming along the Colorado River in Travis and Bastrop counties. The study also looked at rangeland and row cropped familand to estimate which land use type produced more runoff and pollution to receiving streams. Best management practices were also looked at as a means of limiting the amount of runoff and pollution transport from row cropped areas. Three automated sampling sites were set up to collect water samples after rainfall events. Two of the sites were set up to sample from streams that drained subwatersheds of a tributary to the Colorado River. The land use at one subwatershed consisted primarily of rangeland and pastureland while the land use at the other site consisted mainly of row cropped farmland. The third site was set up to sample on a row cropped farm that employed certain best management practices. The accepted convention is that rangeland produces less runoff @ row cropped areas and therefore contributes less pollutants to receiving waters. The findings from this project generally support this. Additionally, it was found, through computer modeling, that best management practices in the form of terracing, contour plowing and filter strips significantly reduced the amount of runoff and pollutants that move off site from row cropped areas during rainfall events. The implications of these findings are that, where possible, efforts should be made to implement best management practices to reduce the amount of runoff and pollution to receiving waters. Producers also need to be educated as to how to implement and maintain best management practices to obtain optimal benefits.