Effects of Different Fertilization Methods on Availability of Soil Nutrient and Rice Yield under Reducing Application Rate of Mineral Fertilizer

A field experiment was carried out to study the effects of different fertilization methods on the availability of soil nutrient and rice yield under the condition of reducing the application rate of mineral fertilizer.The results showed that under the condition of the combined application of 80% chemical fertilizer and 22500 kg/hm2 green manure(Astragalus sinicus),in comparison with the customary fertilization method,the fertilization method which basal fertilizer:tillering stage dressing:panicle fertilizer was 5:5:0 could increase the content of available N in the soil after the harvest of early rice and late rice by 5.6% and 9.8% respectively;the fertilization method which basal fertilizer:tillering stage dressing:panicle fertilizer was 3:4:3 could obviously increase the content of available K in the soil after the harvest of early rice and late rice by 8.9% and 13.2% respectively.Under the condition of the combined application of 60% chemical fertilizer and 22500 kg/hm2 green manure,the fertilization method which basal fertilizer:tillering stage dressing:panicle fertilizer was 5:5:0 could significantly increase the content of available K in the soil after the harvest of early rice by 27.1% as compared with the customary fertilization method;when basal fertilizer:tillering stage dressing:panicle fertilizer was 0:10:0,the content of available N and K in the soil after the harvest of early rice or late rice was decreased.Under the condition of the combined application of 60%-80% chemical fertilizer and 22500 kg/hm2 green manure,the yield of both early rice and late rice was the highest when basal fertilizer:tillering stage dressing:panicle fertilizer was 0:7:3.