Effects of Lower Fertilizer on Rice Growth and Nitrogen Use Efficiency

Field experiments were carried out in slop land area near Chaohu Lake Basin to study rice growth and fertilizer use efficiency of reducing nitrogen application rate throughout the entire rice growing season with the purpose of providing the farmers with scientific basis in promoting reduction of nitrogen application rate.Results showed that reduced nitrogen application rate by 30% in middle-high fertility paddy soil,20% in middle-lower fertility paddy soil rice yield didn't reduce significantly.The reason is that reduced nitrogen application rate and applied nitrogen in different growth stages could increase filled grain number per panicle and 1000 grain weight,compared with the treatment applied all the nitrogen as basal fertilizer.Nitrogen harvest index of the treatment with current nitrogen application rate was the lowest.Reduced nitrogen application rate and applied nitrogen in different growth stages could promote nitrogen transformation from stem,leave and root to grain in different fertility soils.Reduced nitrogen application rate could increase nitrogen use efficiency by 9.99-16.52 percentage points in middle-high fertility paddy soil,6.0-12.15 percentage point in middle-lower fertility paddy soil.