Effects of No-till, Residue Management and Buffer Strips On Sediment and Nutrient Runoff From a Cropped Calcareous Soil.

Sediment, nitrogen and phosphorus carried in agricultural runoff remain an important source of pollution for water bodies across the nation. As a result, developing and evaluating best management practices (BMPs) that could help reduce non-point source pollution from agricultural lands is very important. This study evaluated the effectiveness of no-till, residue management and buffalograss buffer strips as BMPs for reducing sediment and nutrient runoff from croplands. The study was conducted on cropped 302 m² plots sloped at approximately 2% on an Udic Haplusterts. Runoff was measured and sampled using a combination of 0.75 H-type flumes, depth loggers and portable automatic runoff samplers. Nutrients and sediment transported in runoff were quantified using established methods. All the BMPs investigated reduced runoff volume, sediment and nutrients transported to the edge-of-field.  The buffer strip was the most effective BMP followed by no-till and then residue management. Only NO₃-N transport reductions by the BMPs was statistically different (p<0.05) from the control which was conventional tillage. However, reductions in runoff volume ranged from 40.8% to 61.6%, while sediment ranged from 56.2% to 67.5%.  Orthophosphate (PO₄-P) and N reductions in runoff by the BMPs ranged from 15.4% to 72.7% and 22.4% to 86.4%, respectively. The results suggest that combining grass buffer strips with no-till cultivation would be a more effective practice for mitigating sediment and nutrient loading in agricultural watersheds.