Energy Flow And Emergy Analysis Of Corn/Soybean Strip Intercropping Model

The agricultural ecosystem is a complex system affected by land management and human influence,and a good composition structure is a prerequisite for the sustainable development of the agricultural ecosystem.In the agricultural production process,applying nitrogen fertilizer can improve crop production capacity and increase yield.However,excessive application of nitrogen fertilizer leads to nitrogen loss,leading to serious ecological problems.In order to achieve high crop yield and reduce environmental pollution caused by the application of fertilizers,people are increasingly paying attention to the research of reducing nitrogen application.In this study,the maize soybean strip intercropping(IMS)system was studied,with maize monoculture(MM)and soybean monoculture(SS)as controls,using three levels of nitrogen fertilizer: constant nitrogen application(CN),reduced nitrogen application(RN),and no nitrogen application(NN).The experiment analyzed the changes in yield,dry matter accumulation,and nutrient accumulation under different planting and cultivation modes and different nitrogen application rates.Study the material flow of the system under different planting and cultivation modes,and evaluate the environmental and economic benefits of the system using energy flow analysis and energy value analysis methods,providing theoretical basis for optimizing the belt intercropping mode of corn and soybean and applying nitrogen fertilizer management.The main research findings are as follows:1.Under different nitrogen application levels,the land equivalent ratio(LER)of maize soybean intercropping(IMS)system was 1.84(NN),1.66(RN),and 1.89(CN),respectively,with LER>1,indicating intercropping advantages.Under the treatments of no nitrogen application(NN),reduced nitrogen application(RN),and constant nitrogen application(CN)levels,the yield of maize intercropping(IM)increased by-11.49%,-13.62%,and 9.66% compared to maize monoculture(MM),respectively.The yield of soybean intercropping(IS)decreased by 6.89%,28.28%,and 27.44% compared to soybean monoculture(SS).The change in dry matter accumulation is the same as the change in yield.2.Under the same nitrogen application level,compared with maize monoculture(MM),maize intercropping(IM)showed an increase of 1.29%,-8.40%,and-0.29% in carbon content in maize under no nitrogen application(NN),reduced nitrogen application(RN),and constant nitrogen application(CN)treatments,respectively.Compared with soybean monoculture(SS),soybean intercropping(IS)reduced soybean carbon content by26.17%,14.62%,and 0.82%,respectively.The nitrogen content in corn increased by13.53%,-6.71%,and 10.40% in the treatments of no nitrogen application(NN),reduced nitrogen application(RN),and constant nitrogen application(CN),respectively.Compared with soybean intercropping(IS)and soybean monoculture(SS),soybean nitrogen content decreased by 26.40%,29.18%,and 11.97%,respectively.The phosphorus content in corn decreased by 8.33%,3.52%,and 17.62% in the treatments of no nitrogen application(NN),reduced nitrogen application(RN),and constant nitrogen application(CN),respectively.Compared with soybean intercropping(IS)and soybean monoculture(SS),soybean phosphorus content decreased by 34.83%,30.95%,and 8.95%,respectively.The potassium content in corn increased by 20.62%,-4.58%,and 6.85% in the treatments of no nitrogen application(NN),reduced nitrogen application(RN),and constant nitrogen application(CN),respectively.Compared with soybean intercropping(IS)and soybean monoculture(SS),soybean potassium content decreased by 16.54%,13.19%,and 3.36%,respectively.Among the three cultivation modes,the maize monoculture mode showed a deficit state when the nitrogen and potassium production to investment ratio was greater than 1 under reduced nitrogen application conditions,as well as the intercropping mode and soybean monoculture mode,while the phosphorus production to investment ratio was less than 1,showing a surplus state.However,under constant nitrogen application conditions in the corn monoculture model,when the potassium production to investment ratio is greater than 1,it presents a deficit state,while when the nitrogen and phosphorus production to investment ratio is less than 1,it presents a surplus state.3.Under maize intercropping(IM)and maize monoculture(MM)cultivation modes,the energy output of maize showed that reduced nitrogen application(RN)was superior to constant nitrogen application(CN)and superior to no nitrogen application(NN);In the soybean intercropping(IS)and soybean monoculture(SS)models,constant nitrogen application(CN)was superior to reduced nitrogen application(RN)and no nitrogen application(NN).Under different nitrogen application levels,the energy yield to input ratio of IMS,MM,and SS showed that no nitrogen application(NN)was higher than reduced nitrogen application(RN)and constant nitrogen application(CN).Under the same cultivation mode,the energy yield to input ratio and energy flow cycling index of reduced nitrogen application(RN)were better than those of constant nitrogen application(CN).The utilization rate of light energy in IMS and SS shows that CN is superior to RN and superior to NN,but in MM it shows that RN is superior to CN and superior to NN.4.Under the maize monoculture(MM)cultivation mode,the emergy output showed that reduced nitrogen application(RN)was superior to constant nitrogen application(CN)and superior to no nitrogen application(NN);In the maize soybean intercropping(IMS)model and soybean monoculture(SS)model,constant nitrogen application(CN)was better than reduced nitrogen application(RN)than no nitrogen application(NN).Under the same nitrogen application level,the maize soybean intercropping(IMS)model is higher than soybean monoculture(SS)and maize monoculture(MM).The macroeconomic value performance is the same.Reduced nitrogen application(RN)reduced the energy input of the system compared to constant nitrogen application(CN),and increased energy output compared to no nitrogen application(NN).Reduced nitrogen application(RN)has increased macroeconomic value and reduced environmental load rate.Compared to soybeans,corn has a higher environmental loading rate and a lower energy output rate.In terms of economic benefits,the intercropping cultivation mode is superior to the monoculture mode,and the application of nitrogen fertilizer is appropriately reduced to increase the planting area or density of soybeans in a certain space,thereby improving the economic benefits of the maize soybean intercropping mode.5.In the same cultivation mode,the output value of constant nitrogen application(CN)and reduced nitrogen application(RN)is higher than that of no nitrogen application(NN).The same applies to net profits in maize soybean intercropping(IMS),maize monoculture(MM),and soybean monoculture(SS)models.However,in the production to investment ratio,there is a situation where the treatment without nitrogen application(NN)is higher than the constant nitrogen application(CN)and reduced nitrogen application(RN),as the input of nitrogen fertilizer accounts for a large production cost in the entire production system and the harm of nitrogen fertilizer to the environment is not considered.Under the condition of increasing nitrogen fertilizer application,the yield to investment ratio of reduced nitrogen application(RN)is higher than that of constant nitrogen application(CN).Reduced nitrogen application(RN)helps to improve the economic benefits of maize soybean intercropping cultivation mode.