Effects Of Nitrogen Supply Level On Dry Matter Accumulation And Nutrient Absorption In Maize/soybean Intercropping System

Maize/soybean intercropping has yield advantage in some extent.However,different nitrogen supply levels have different effects on dry matter accumulation and nitrogen uptake in the maize/soybean intercropping system.Field experiment with a spit design and logistic model were used to simulate dynamic changes of dry matter accumulation and nutri ent uptake the in maize/soybean intercropping system supplied with four nitrogen levels.,the main findings are as follows:(1)Simulation results showed that the dry matter accumulation and nitrogen uptake dynamics in maize and soya were consistent with Logistic model,which the correlation coefficients(R2)were more than 0.9at the four nitrogen levels.The maximum growth rate(Imax)of intercropped maize compared with monoculture increased by 34.18%,46.68%,25.92% and 25.01%when nitrogen supply levels were N0(blank control),N1(110 kg·hm-2),N2(160 kg·hm-2)and N3(210 kg·hm-2),respectively.While the Imax of soybean decreased by27.69%,30.26%,16.54% and 23.74% at the corresponding nitrogen supply level.But the average Imax of the intercropping system was increased by32.10%.Other dry matter simulation parameters of maize and soybean were consistent with Imax.(2)Nitrogen uptake dynamics and dry matter accumulation showed synchronous changes.At N1 treatment,the maximum nitrogen uptake(K),maximum upta ke rate(Imax)and instantaneous uptake rate(r)of intercropping maize were 18.35%,48.96% and 25.81% higher than monoculture,while the K,Imax and r of intercropping soya bean were 15.91%,29.98% and 16.69% lower than monoculture,and the K,Imax and r of Intercropping system were 0.41%,13.68%and 7.80% higher than monoculture respectively.Nitrogen supply had no significant effect on the average absorption rate(r)of soya bean.Phosphorus and potassium uptake dynamics and nitrogen uptake showed synchronous changes.The application of nitrogen fertilizer in intercropping mode effectively increased P and K in maize,and the intercropping mode significantly shortened the time Tmax for maize and soybean to reach the maximum P accumulation.There was no sign ificant effect on potassium Tmax and R in maize and soybean.(3)Intercropping population is dominated by interspecific competition.Intercropping system has significant nutrient advantage(LERN>1),and the LERN value in N0 treatment was the highest.With the increase of nitrogen application,the nitrogen LERN has a downward trend.Through the calculation and analysis of nutrient uptake,economic yield utilization and biological nutrient utilization rate,the intercropping system can improve the nutrient upt ake of crops,in which the N2 level in intercropping mode has the highest N uptake,with a range of 14.25%.The intercropping system has the ability to improve the N fertilizer use efficiency of grains.The nutrient use efficiency of biological yield increased with the increase of nitrogen level,and the intercropping system had the highest nitrogen uptake at N3 level,which increased by 6.68% compared with monoculture.(4)Intercropping system has significant yield advantage(LER>1),which the intercroppin g advantage was most significant at N0 and N2 levels.The level of nitrogen supply and intercropping had significant effects on Maize yield,and the application of nitrogen fertilizer in intercropping mode was better than that of nitrogen fertilizer alone.Among them,the maize yield of N2 IM and N3 IM treatments increased by 40.19% and 47.50% compared with N2 M and N3 M treatments,respectively,and was 1.04 and 1.19 times higher than that of N0 S treatments.Under intercropping mode,nitrogen fertilizer could increase maize yield,and maize yield under N2 IM treatment was 24.81% higher than that under N2 M treatment.The yield of soybean in intercropping system was significantly reduced.The yield of soybean in N2 IS treatment was 6.19% lower than that in N2 S treatment,but the total yield of the whole intercropping system was 20.54% higher than that of single cropping.The results showed that intercropping could increase the yield of the whole intercropping system,and nitrogen application could also increase the yield.