Effects of Rice-green Manure Crop Cropping Systems on Soil Characteristics and Rice Yield in Paddy Field

Supplying rate of nitrogen at HV was 172.8 kg $ha^{-1}$, HV/B was 64.3 kg $ha^{-1}$ and B was 38.6 kg $ha^{-1}$. The Rice yield was 7.05 ton $ha^{-1}$ when the nitrogen supply was the largest with HV and 5.42 ton $ha^{-1}$ was produced on HV/B. The chemical characteristics of soil have lower pH and exchangeable cations(Ca and Mg) at B, HV and HV/B, rather than at CF because green manure was applied at the former step. However, the physical characteristics of the soil and the porosity showed different tendency which was that it was better at the green manure crops than CF. Nitrogen nutrient balance was showed the most balanced at CF and field of application of green manure crops were required the appropriate management if future crops would be cultivated because nitrogen nutrient could be exhausted or accumulated.