Effects Of Different Intercropping Ratio Of Maize And Alfalfa And Nitrogen Application Level On Crop Growth And Soil Environment

In the process of agricultural production,the application of nitrogen fertilizer has a great influence on the yield and quality of crops.In addition to applying nitrogen fertilizer,for example,intercropping between different crops can also improve crop yield and quality.Maize and legume intercropping mode can achieve stable crop production and increase crop yield,which is one of the most effective cropping modes in the development of sustainable agricultural production.Different bandwidth-to-row ratios also have an impact on crop yields,bandwidth row ratio allocation plays an important role in crop growth and population yield benefit in intercropping system.Therefore,it is very important to find suitable nitrogen application level and row ratio to improve the yield and quality of maize.Through a field soil test at a water-saving irrigation base in Taiyuan’s Xiaodian district to study the effects of maize and alfalfa intercropping row ratio and nitrogen application level on crop growth and soil environment.There were 4 types of nitrogen levels[N₀（nitrogen application amount is zero）,N₁₀₀（nitrogen application amount is 100 kg/hm²）,N₂₀₀（nitrogen application amount is 200 kg/hm²）and N₃₀₀（nitrogen application amount is 300 kg/hm²）]and three planting patterns[maize and alfalfa intercropping with row ratio of 1:2（intercropping of1 row of maize and 2 rows of alfalfa）,maize and alfalfa intercropping with row ratio of 2:2（intercropping of 2 rows of maize and 2 rows of alfalfa）,maize monoculture],to conduct a complete randomized trial.By studying the effects of different nitrogen application levels on soil water content,electrical conductivity,p H value,growth index,crop yield and soil nitrogen in maize alfalfa intercropping mode,the suitable row ratio and nitrogen application level of maize alfalfa intercropping were found,which provided scientific basis for improving crop yield and nitrogen use efficiency under maize Alfalfa intercropping mode in Xiaodian District of Taiyuan city.The main research results of this thesis are as follows.（1）Soil moisture content decreases first and then increases with the increase of nitrogen application amount,the soil moisture content under N₀ treatment was the highest,and the soil moisture content under N₂₀₀ treatment was the lowest.The R² of simulated value of HYDRUS-1D model and actual value is 0.74～0.89,RMSE is 0.01～0.03 and NSE is 0.71～0.91,which shows the simulation is accurate.It is found that increasing nitrogen fertilizer and changing planting modes has no significant effect on soil conductivity.Increasing nitrogen fertilizer application has a significant effect on soil p H,and the more nitrogen application,the higher soil p H.Changing the intercropping modes also has a significant effect on soil p H,and the intercropping mode with row ratio of 1:2 has a greater increase in soil p H.（2）Applying nitrogen fertilizer to maize and intercropping alfalfa could both significantly increase the height of maize.Under the same planting mode,compared with N₀ treatment,N₂₀₀treatment has the most obvious promoting effect on the height of maize,and improving by13.33%under maize monoculture mode,16.27%under intercropping mode with row ratio of1:2,14.01%under intercropping mode with row ratio of 2:2.Under the same nitrogen application level,the height of maize in intercropping modes is higher than that in monoculture.With the increase of nitrogen application amount,the leaf area and stem diameter of maize first increases and then decreases,and reaches the peak value under N₂₀₀ treatment.The application of nitrogen fertilizer and intercropping both has no significant effect on ear height of maize.（3）Under the same planting pattern,different nitrogen application level could not significantly increase the ear length and ear diameter,but significantly increases grain number per ear and the 100-grain weight of maize.Under the same nitrogen application level,compared with maize monoculture,maize and alfalfa intercropping with row ratio of 2:2 increased the corn yield components more significantly.The yield of maize treated with nitrogen fertilizer was increased and reaches a significant level,and N₂₀₀ treatment has the largest yield,which is8.12 kg/hm²,8.65 kg/hm² and 8.82 kg/hm² under the three planting modes,respectively.Although the maize yield of maize and alfalfa intercropping system is higher than that of maize monoculture,it does not reach a significant level.Maize and alfalfa intercropping with row ratio of 2:2 has better promotion effect on maize yield.Nitrogen application significantly increases dry matter accumulation of maize.N₂₀₀ treatment have the best promoting effect,and compared with N₀ treatment,dry matter accumulation of maize under the three planting modes is increased by 45.82%,42.57%and 46.01%,respectively.（4）Under different planting modes and different nitrogen application amount,compared with monoculture maize and alfalfa intercropping could increase the accumulation of nitrate nitrogen and ammonium nitrogen in the soil.N₃₀₀ treatment has the best improvement effect,and compared with monoculture,1:2 and 2:2 intercropping modes increases nitrate nitrogen accumulation by 15.69%and 22.60%,respectively,and ammonium nitrogen accumulation by11.09%and 20.60%,respectively.There was no significant difference in soil nitrate nitrogen content and accumulation between N₂₀₀ and N₃₀₀ treatments.On the contrary,excessive application of nitrogen fertilizer would lead to a large amount of nitrogen loss due to nitrate leaching.Appropriate reduction of nitrogen fertilizer application would not reduce crop yield,but also excessive application of nitrogen fertilizer will pollute the environment.（5）From the aspects of saving fertilizer,increasing yield and protecting environment,the suitable planting mode in Xiaodian District of Taiyuan city is maize alfalfa 2:2 intercropping,and the the fertilizer is 200 kg/hm².