To use barley as a green manure crop, this study has been conducted in Suwon, Gyeonggi-do to establish the barley green manure (BGM)-rice cropping system with emphasis on soil incorporation date and BGM density. The nitrogen (N) contents of rye and barley, grass green manure crops, were 1.4-2.4% at early growth stage and decreased rapidly to 0.6-1.0% at late growth stage. The biomass of barley was 449 kg/10 a at heading stage (HS) and increased to 421 kg/10 a at 10 days after heading stage (DAH), 473 kg/10 a at 20 DAH. C/N ratio of BGM was the lowest 26.3 at HS. The N contents of BGM was in the range of 0.9-1.5%, the highest at HS and gradually decreased, and the output of N were 4.3-6.3 kg/10 a. The total amount of nitrogen, phosphorous and potassium of BGM showed the highest level at 10 DAH. Culm length of rice was relatively longer as the BGM application time was delayed. The application of BGM into soil increased plant height of rice by 7.2-7.7 cm as compared to the plants treated with commercial fertilizer at recommended rate, but panicle length of rice showed a similar tendency in both the soil-applied of BGM and commercial fertilizer. N contents of unhulled rice was the highest at HS of BGM and followed by 10 DAH of BGM and 20 DAH of BGM. This trend could also be seen in rice straw. The yield of rice in the soil-applied of BGM was 10-15% lower than in the soil-applied of commercial fertilizer. Based on this study, application of BGM made it possible to save 30-50% of application amount of nitrogen fertilizer for following crops.
