Effects Of Combined Application Of Organic And Inorganic Fertilizers And Irrigation Methods On Rice Yield And Nitrogen Use Efficiency

In order to save fresh water resources,reduce the amount of chemical fertilizer,and realize water and fertilizer coordination and efficient utilization of resources,two irrigation methods（W1 water layer irrigation,W2 wet irrigation）and four nitrogen application levels（N0:no nitrogen application;N0:no nitrogen application）;N1:N 150 kg·hm^-2 n,100%urea nitrogen;N2:N 150 kg·hm^-2,80%urea nitrogen+20%organic nitrogen（vegetable wilt）,N 3:N 150 kg·hm^-2,60%urea nitrogen+40%organic nitrogen（vegetable wilt）,the effects of water fertilizer coupling and organic-inorganic fertilizer on matter production and nitrogen use efficiency of super rice were studied（1）Irrigation methods had little effect on rice population,and W1 was slightly higher than W2.The total trend was that the number of tillers in N1 was the most,and the number of tillers in N1 was 8.5%,25.0%and 34.5%higher than that in N2,N3 and N0,respectively.The results showed that the tiller number decreased when 20%vegetable wilt was used instead of urea,and the tiller number decreased more when 40%vegetable wilt was used instead of urea.（2）Among different irrigation methods,the leaf area index of W1 was higher than that of W2,indicating that slight water stress would limit the expansion of leaf area under moist irrigation.Among different nitrogen application treatments,the leaf area index of N0 without nitrogen application was lower than that of nitrogen application,and the leaf area index of N1 with inorganic nitrogen application was the highest.The more organic fertilizer substitution,the lower the leaf area index.From the interaction of water and nitrogen,the area index of w1n1 leaf was the largest and w2n0 leaf was the smallest.（3）Irrigation methods had no significant effect on SPAD value of leaves.The SPAD value of N0 without nitrogen application was lower than that of N0 with nitrogen application,and N1 with inorganic nitrogen application was the highest.At full heading stage,N1 was13.50%,0.04%and 11.00%higher than N0,N2 and N3,respectively.The results showed that the application of nitrogen fertilizer could increase the chlorophyll content,and the effect of inorganic nitrogen fertilizer was more obvious.（4）The dry matter accumulation of W2 was 7.29%more than that of W1,which reached a significant level.According to different nitrogen application treatments,the accumulation of dry matter in different parts of plants at different growth stages was higher in N1,N2 and N3 than that in N0,with significant or extremely significant differences,respectively.The dry matter accumulation of the whole plant was W2N1>W1N1>W2N2>W1N2>W2N3>W1N3>W2N0>W1N0.（5）The photosynthetic rate of W2 was higher than that of W1.Under different nitrogen treatments,the photosynthetic rate of N1 was 20.85%at tillering stageμ41%,19.55%and17.53%higher than N2,N3 and N0,respectively;At the late growth stage（full heading stage to grain filling stage）,N3>N2>N1>N0,N3 and N2 were significantly different from N1 and N0,but there was no significant difference at grain filling stage.（6）The yield of W2 increased by 4.07%compared with W1.The yield of N3,N2 and N1 was 28.32%,25.52%and 18.88%higher than that of N0,respectively.The differences among N3,N2 and N1 were also significant.The highest yield was W2N3（7.42 t/hm²）,followed by W2N2 and W1N3（7.25 t/hm²）.（7）There were some differences in nitrogen use efficiency among different irrigation methods.Compared with W1,W2 had higher nitrogen uptake efficiency,agronomic efficiency and partial Nitrogen productivity,but lower physiological efficiency.From the perspective of nitrogen application,nitrogen absorption and utilization efficiency,Nitrogen Agronomic utilization efficiency and nitrogen partial productivity were N3>N2>N1.The nitrogen use efficiency of N3 was 78.52%,7.01 percentage points higher than that of N1;The agronomic use efficiency of nitrogen fertilizer in N3 was 9.77kg/kg,which was 15.62%higher than that in N1.Nitrogen partial productivity of N3 was 48.90kg/kg,6.93%higher than that of N1.