Effects Of Different Nitrogen Application Amount On Yield And Nitrogen Utilization Of Silage Maize(Zea Mays L.)/Fodder Soybean(Glycine Max Merr.) Mixed Sowing

The mixed planting of gramineous and leguminous plants is an important form of cultivation for planting structure adjustment and soil quality improvement.It can increase forage yield,quality and nitrogen use efficiency.In this study,the mixed-sowing system of silage maize and fodder soybean(Glycine max Merr.)was used as the research object,three different mixed sowing proportions(silage maize:fodder soybean=1:1,1:2,1:3)and three fertilization gradients(base fertilizer,optimized fertilization,traditional fertilization)were set up to carry out the field experiment.The total nitrogen content in silage maize and fodder soybean and nitrogen content in each state of the soil was dynamically analyzed,and the yield and nitrogen use efficiency of different mixed sowing groups were compared.The results were as follows:1.Under the respective nitrogen application levels,the yield reached the maximum when the mixed sowing ratio was 1:2,which was 72680kg/hm~2(base fertilizer),87470 kg/hm~2(optimized fertilization)and 92265 kg/hm~2(traditional fertilization).Under the conditions of various mixed sowing ratios,the forage yield was increased with the increase of nitrogen application amount,which reached the maximum in the traditional fertilization amount,which was 88077kg/hm~2(mixing ratio 1:1)and 92265 kg/hm~2(mixing ratio1:2),87239 kg/hm~2(mixing ratio 1:3).2.Under the condition of only applying the base fertilizer,when the mixed sowing ratio was1:1 and 1:2,the nitrogen nutrition competition ratio of the mixed combination was 2.53 and 2.19,respectively,indicating that the competition ability of silage maize for nitrogen was stronger than that of fodder soybeans.When the mixed sowing was 1:3,the nitrogen nutrition competition was0.88,indicating that the fodder soybeans had stronger competition ability for nitrogen than silage maize.3.The soil equivalent ratios were 1.31,1.55 and 1.87 respectively when the basal fertilizer was applied at different mixed sowing ratios,that is,the mixed cropping was superior to the single cropping.When the mixed sowing ratio was 1:3,the advantage of mixed cropping was the largest.4.Under the same nitrogen application conditions,soil total nitrogen,nitrate nitrogen,ammonium nitrogen,and total nitrogen content of maize increased with the increase of planting density of fodder soybeans in 0-20 cm soil layer.Only under the traditional fertilization conditions,the ammonium nitrogen content was lower at the mixed sowing ratio of 1:3 than the mixed sowing ratio of 1:2.The total nitrogen content of the fodder soybean was decreased as the density of the fodder soybean increased.5.Under the same mixed sowing ratio,the total nitrogen,nitrate nitrogen,ammonium nitrogen,and the total nitrogen content of maize and fodder soybean were increased with the increase of fertilizer application in 0-20 cm soil layer.6.When the optimized fertilization was applied and the mixed sowing ratio was 1:2,the nitrogen absorption rate was the highest,which was 12.597%.When the optimized fertilization was applied and the mixed sowing ratio was 1:3,the total available nitrogen utilization rate was the highest,which was 34.215kg/kgN.When the base fertilizer was applied and the mixed sowing ratio was 1:2,the nitrogen plant production efficiency was the highest,which was 96.332 kg/kgN.7.When the mixed sowing ratio was 1:2,the forage yield under traditional fertilization conditions was higher than that under optimized fertilization conditions,but the difference between the two was not significant,so the optimal fertilization and the mixed sowing ratio of 1:2was the ideal production way.