Effects of green manure crops and mulching technology on reduction in herbicide and fertilizer use during rice cultivation in Korea

Green manure crops are primarily used in environmentally friendly agricultural practices to reduce the application of chemical fertilizer and herbicide. In this study, a two-year field experiment was conducted to evaluate the effects of paper and plastic mulching with hairy vetch alone or in combination with barley on weed control and rice yield. In addition, treatment effects on soil redox potential (Eh) and the concentration of ammonium (NH₄⁺) in rice paddy were investigated. The results showed that plastic film (10 or 20 μm) and paper mulching with hairy vetch alone had no significant effects on weed density and rice yield when compared with conventional practice (herbicide and fertilizer application) during the first year. However, during the second year, plastic film (20 μm) with partial tillage of hairy vetch alone increased rice yield and decreased weed occurence; but barley and hairy vetch mixture showed opposite trends. Plastic film mulching led to a decrease in soil redox potential, mainly due to the decomposition of soil organic matter. In addition, plastic film mulching increased NH₄⁺ -N contents in rice paddy soil. These results suggest that the combination of plastic film with hairy vetch and barley mixture can be used in rice fields to reduce the use of chemical fertilizer and herbicide.