| Two experiments were conducted in the field in Ezhou, Hubei province. To provide more green manure crops grown well in the paddy in South China, the differences of growth and nutrient accumulation of green manure, the effect of green manure on the absorption and yield of rice and soil fertility were studied in the first experiment. In order to combine utilizing and increasing fertility of the rice paddy, the influence of rape intercropping with Astragalus sinicus L. on yields of rapeseed, the application of Astragalus sinicus L and rape straw on rice production and soil fertility were studied in the second experiment. The main results were as follow:(1)In paddy field in Hubei province, the biomass of Vicia faba L. was the largest in5green manure crops, the following were V. villosa var., Vicia sativa L., Vicia villosa Roth, that of Astragalus sinicus L. was the lowest. The accumulation of N, P2O5, K2O, C in the first four kinds of green manure crops were also higher than Astragalus sinicus L.(2) Rice yield applying green manure crops like V. villosa var., Vicia sativa L., Vicia faba L., Vicia villosa Roth, were higher than those of Astragalus sinicus L. After combined application of30%less fertilizers than local grower and green manure like V. villosa var., Vicia sativa L. or Vicia faba L., rice yield was still increased by1.5%-6.6%than the single application of100%fertilizer without green manure. The main reason why rice yield was increased were that the number of panicles and grains per panicles were improved by combined application of winter leguminous green manure and chemical fertilizer.(3) The partial factor productivity and agronomic efficiency of fertilizer were improved due to combined application of green manure. Compared with single application of chemical fertilizer, the partial factor productivity and agronomic efficiency of applied fertilizer combined with V. villosa var., Vicia faba L., Vicia sativa L., Vicia villosa Roth., Astragalus sinicus L. were increased by69.9%,62.5%,62.1%,57.1%,54.1%and71.6%,50.4%,49.4%,50.4%,26.5%respectively.(4) The accumulation of N, P2O5, K2O in shoots of rice were promoted owing to applying winter green manure. The N accumulation in shoot of rice applied70%chemical fertilizer combined with V. villosa var., Vicia faba L., or Vicia sativa L. was higher than those of100%chemical fertilizer without green manure. The accumulation of P2O5and K2O in shoots of rice applied70%chemical fertilizer with green manure were greater than those of70%chemical fertilizr without green manure, but less than 100%fertilizer without green manure., which indicated the ability to provide nitrogen of green manure was higher than phosphorus and potassium in the rice field in Hubei province.(5) The application of green manure was helpful to improve the soil fertility. Compared with100%chemical fertilizer without green manure, the application of green manure increased soil organic matter by2.7%-8.6%, soil total nitrogen by1.1%-3.4%, available potassium by1.3%-14.0%and available phosphorus by0.8-1.6times. The increase in V. villosa var., Vicia faba L., Vicia sativa L. and Vicia villosa Roth, was better than that in Astragalus sinicus L.(6) The rapeseed yield under single cropping was not significantly different with intercropping of rape and Astragalus sinicus L. under proper sowing proportion. When the straw from the two planting patterns was returned to soil, the rice yield were increased by2.6%and4.1%compared with winter fallow, the economic benefit in whole year were improved by63.6%and54.4%, respectively.Turning down the straw of Astragalus sinicus L. and rape for two consecutive years, soil organic content in rape-rice and rape intercropping with Astragalus sinicus L.-rice were increased by1.1%and1.3%, respectively, than the winter fallow-rice, with a higher intensity in rape intercropping with Astragalus sinicus L.-rice. There were a similar trend on the content of available phosphorus and available potassium in soil. |
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