Crop residue effects on nitrogen yield in water and sediment runoff from two tillage systems

Abstract

Simulated rainfall was used on experimental plots to study the effects of three crop residue levels (0, 750, and 1500 kg ha −1) on nitrogen yield in runoff from no-till and conventional tillage systems. The study site was located near Blacksburg, Virginia. Soil type at the research plots belong to Grose-close Series which is predominant in southwest Virginia. Approximately 100 mm of simulated rainfall with a 50 mm h −1 intensity was applied to 12 experimental field plots. Nitrogen fertilizer was applied at a rate of 147 kg ha −1 prior to rainfall simulation. Water and sediment samples were collected from H-flume discharge at the base of each plot and were analyzed for nitrogen concentration. Nitrogen yield was calculated from nitrogen concentration and the corresponding flow rate at sampling time. Results indicated that at all residue levels, the no-till system was more effective in reducing nitrogen in water and sediment compared to conventional tillage. For both systems, crop residue levels at 750 kg ha −1 were very effective in reducing nitrogen yield in runoff. However, at 1500 kg ha −1 residue level higher nitrogen yields were observed. It was demonstrated that no-till system combined with appropriate residue management could reduce nitrogen yield in runoff and therefore can be considered an effective measure for reducing nitrogen input to surface water bodies. However, the relative effects of tillage practices on groundwater quality cannot be deduced from this study.