Study On The Variation Characteristics Of Crop Yield,carbon And Nitrogen Accumulation And Soil Nutrients Under Sweet Corn || Soybean Intercropping System In Upland Red Soil

In order to study the effects of interspecific competition and nitrogen reduction on crop yield,carbon and nitrogen absorption accumulation and soil nutrient in different planting modes of Zea mays L.and Glycine max merri.in upland red soil,a field experiment was conducted in Agricultural Science and Technology Park of Jiangxi Agricultural University（2018-2020）.The experiment was designed by using three nitrogen application levels(N0,0 kg·hm^-2;N1,150 kg·hm^-2;N2,300 kg·hm^-2)and three planting modes（MC,Sweet corn sole cropping;MS,Soybean sole cropping;CS,Sweet corn‖soybean intercropping）.The planting system of sweet corn and soybean was studied from four aspects:crop productivity（yield,dry matter accumulation and agronomic characters）,carbon and nitrogen absorption accumulation,interspecific competition analysis（Invasion（Ag）and competition ratio（CR））,soil nutrients,etc.The results show that:1.The yield of sweet corn in three years showed that the yield of sweet corn was significantly increased by applying nitrogen fertilizer than without nitrogen,and the stem diameter,ear height and plant height agronomic characters of sweet corn were increased.Compared with N2（conventional nitrogen application）,N1（reduced nitrogen application）had no significant negative effect on the agronomic characters of sweet corn.Under the same planting mode,there was no significant difference in yield of sweet corn at N1 level compared with N2.The effect of intercropping and nitrogen application on soybean yield and dry matter was small.2.From the perspective of nitrogen application level,fertilization significantly increased the carbon and nitrogen absorption accumulation of sweet corn than that of non fertilization,and the effect of N1 and N2 on the carbon and nitrogen absorption and accumulation of sweet corn was not significantly different.From the perspective of planting mode,the carbon and nitrogen absorption accumulation of sweet corn and soybean is lower than that of sole cropping sweet corn and soybean,but the total absorption accumulation of planting mode is higher than that of sweet corn or soybean sole cropping.3.From the perspective of the competition relationship between the varieties of sweet corn soybean planting system,the intercropping system showed obvious intercropping advantages（Land equivalent ratio LER>1,Competition ratio CR>0,Aggressivity AG>1）whether nitrogen was applied or not.Sweet corn has a great competitive advantage in intercropping competition,and the land productivity advantage of sweet corn soybean intercropping mode is mainly reflected in sweet corn.In the first year of planting,no nitrogen application had better intercropping advantage than nitrogen treatment,but with the increase of planting years,nitrogen application was beneficial to maintain the production advantage and inter annual stability of sweet corn under intercropping mode.Compared with the conventional nitrogen application（N2）,reducing nitrogen application（N1）did not significantly reduce the crop productivity and competitive advantage of sweet corn under the intercropping mode of sweet corn soybean,and had better inter annual stability.4.From the perspective of soil nutrients,during the three-year field positioning test,the soil nutrients showed fluctuation,and the amount of nitrogen application increased the content of total nitrogen,nitrate nitrogen,ammonium nitrogen and organic matter,and reduced the soil p H value to a certain extent.Compared with the sole cropping,the intercropping mode has a certain stability on the content of available P and potassium in soil.