Vetch green manure increases rice yields: …Proper depth and timing of incorporation allows maximum results

Purple vetch produces greater rice yields when turned under 4 to 6 inches than when placed at shallower depths. Shortening the time interval between turning under the vetch and flooding and sowing the rice, also increases yields—when conditions are favorable to nitrification during the preflooding period. When properly incorporated, vetch green manure is equal to mineral sources of ammonium nitrogen in increasing rice yields.