Research Of Intercropping Benefit And Nitrogen Absorption Mechanism Of Alfalfa‖Oat Intercropping Systems

In recent years,the deterioration of the environment and soil conditions in the Northern Agricultural and pastoral areas of China has intensified.How to curb the further deterioration of the soil on the basis of ensuring crop yield has become an urgent problem to be solved in this region.Leguminous‖grass crop intercropping is a widely used planting pattern in northern China,which can improve the physical and chemical properties of the soil and protect the ecological environment.Forage production in the Northern agricultural and pastoral areas of China is as important as food production,but most of the intercropping patterns in this area are concentrated in grain-feeding intercropping.In order to improve the yield and quality of forage,the leguminous‖grass forage intercropping model has been carried out in developed countries.Alfalfa and oats are the main pastures in the Northern agricultural and pastoral areas of China.The intercropping pattern can solve the problem of single forage and low yield in the region,and also can improve land utilization and improve soil conditions.Taking alfalfa and oats as research objects,this paper explored the performance of alfalfa and oats under three different patterns（single cropping,intercropping and intercropping isolation）,including aboveground part such as yield,plant height,NDVI and underground part such as soil nitrogen content,water content and other characteristics.Thus,it can be calculated whether intercropping mode has advantages over the single cropping mode,if it has advantages,the source of advantages is the aboveground part or the underground part,and the absorption of nitrogen between the two crops.Furthermore,the dominant factors and limiting factors of the whole intercropping mode are analyzed,and the intercropping mode is optimized.This experiment will provide theoretical and technical support for the promotion of high-yield and high-efficiency forage cultivation model in the Northern Agricultural and pastoral areas of China.The main conclusions of this experiment are as follows:1.The alfalfa‖oat intercropping mode has advantages over the monoculture mode.Intercropping can significantly increase yield,oat biomass yield increased by 14.4%,while alfalfa biomass yield increased by 6.8%.Intercropping advantages can also be reflected in improving land use efficiency,LER value is 1.11,and intercropping can promote crop nitrogen uptake.By calculating the relative contribution rate of above-ground and underground intercropping,it can be concluded that the main source of intercropping advantage is the above-ground part.2.The soil inorganic nitrogen,including NO₃^-and NH₄⁺,has increased after alfalfa‖oat intercropping mode,and the total nitrogen absorbed by alfalfa and oat has increased over the monoculture mode,This planting method will promote the increase of yield and improve soil nitrogen conditions.3.According to the change of soil water content of oat and alfalfa under three different patterning modes,it can be concluded that the soil water of two crops will transfer mutually in different periods within the depth of 1 meter.During the first and third flowering stages of alfalfa,oats at jointing and booting stages in the same period need more water to maintain growth.The results show that water in alfalfa soil will transfer to oat soil.When the second crop of alfalfa is in flowering stage,oats are in tillering stage,and the competition of oats for water is weak,so oat soil water branch will move to alfalfa soil.4.In the alfalfa‖oat intercropping mode,the results showed that the relative competitiveness of alfalfa was higher than that of oat,and alfalfa has an advantage in the nitrogen competition ratio.