Effect of Surface Cover on NPS Pollution from Sloping Fields under Intensive Farming in Korea

Sloping fields under intensive farming have been a major source of agricultural nonpoint source (NPS) pollution in Korea. Comprehensive studies to quantify edge-of-field water quality and measure surface mulch effects on NPS pollution discharge have been conducted over the past several years. Edge-of-field water quality was seriously degraded by NPS pollutants. The range of average event mean concentrations (EMCs) was suspended solids (SS) 547 ~ 2600 mg l−1, biochemical oxygen demand (BOD) 8.7 ~ 50.7 mg l−1, total nitrogen (TN) 3.5 ~ 21.8 mg l−1, and total phosphorus (TP) 2.4 ~ 13.1 mg l−1. Experiments treated by a rice straw mat mulch (S), S with gypsum (SG), and SG with PAM (SPG) showed good results as best management practices (BMPs) in controlling NPS pollution from sloping fields. The range of reductions by the treatments was runoff 28.3 ~ 96.7%, SS 71.5 ~ 99.5%, BOD 37.5 ~ 91.9%, TN 32.4 ~ 91.0%, and TP 43.0 ~ 95.7%. The SPG showed the best reduction effect for both runoff and NPS pollution. The S also showed encouraging results as a prospective BMP. Crop yields under the treatments also increased by up to 740% (lettuce) and 6.1 ~ 39.2% (cabbage and radish). The mulch treatments were proven to be effective for the increase of farm productivity and to improve runoff quality as well. Copyright © 2016 John Wiley & Sons, Ltd.