Surface Runoff Water Quality From Multiple Best Management Practices in North Texas.

Nutrient and sediment runoff from agricultural lands are increasingly becoming a non-point source pollution problem for reservoirs supplying North Texas with water. The overall objective of this ongoing study therefore is to evaluate and quantify the effectiveness of best management practices (BMPs) for reducing surface water nutrient and sediment loading from agricultural runoff. The runoff studies are being conducted on a series of 302 m² plots arranged in a randomized complete block design at approximately 2% slope on Houston black clay soil (Fine, smectitic, thermic Udic Haplusterts). The plots are equipped with H-type flumes, runoff depth measuring devices and automatic samplers for measuring and sampling runoff from natural rainfall. BMPs undergoing evaluation for croplands include stubble management, cover crops and buffer strips while those for pasture lands include nutrient management and range seeding. However this paper will focus only on runoff quality from the cropland BMPs. No significant differences (p<0.05) have been observed for peak concentration values for dissolved phosphorus, nitrate, sediment and other water quality parameters including pH and electrical conductivity (EC) for runoff samples collected over 14 rainfall events ranging from approximately 11 to138 mm from the crop land BMP treatments. Average values for these parameters were 0.3 ± 0.3 mg/L for dissolved phosphorus, 0.5 ± 0.7 mg/L for nitrate, 2052.2 ± 1857.4 mg/L for sediment, 7.8 ± 0.4 for pH and 176.8 ± 82.7 uS/cm for EC.  Nutrient and sediment loads transported to the edge-of-field will be discussed.