Effect of No‐Till Practice on Runoff and Nonpoint Source Pollution from an Intensively Farmed Field in Korea

A 2-year runoff plot study was conducted under simulated rainfall to explore the effects of no-till (NT) practice on the runoff ratio and NPS pollution in an intensive farming region of Korea. Eight 5 × 30 m runoff plots, four each on 3 and 8% slopes, were prepared in existing loamy sand fields. Cultivation in two plots on each slope followed conventional practice (CT). Six rainfall simulations were conducted during the study, each of a nominal 1 h duration and 30 mm h-1 intensity. The runoff ratio of the NT plots decreased 64.9% compared with that of the CT plots. The reduction of NPS pollution load by the NT treatment was 88.3% (SS), 79.0% (CODCr), 86.4% (CODMn), 66.4% (BOD), 67.6% (TN) and 73.6% (TP) compared to losses from the CT plots, with no reduction in average crop yield. Runoff reduction was a key factor in the reduction of pollution loads. The study demonstrated that agricultural NPS pollution loads can be significantly reduced by the application of no-till practice without harming crop productivity. Furthermore, NPS pollution loads can be controlled better if management practices are targeted for runoff reduction rather than concentration reduction. Copyright © 2016 John Wiley & Sons, Ltd.