Impacts Of Intercropping With Cover Crops And Maize On Soil Fertility And Ecosystem Service Value

Problems such as weakened ecosystem services,decreased soil organic matter content,reduced soil fertility,and soil erosion,threaten agroecosystems and food security in Northeast China.Cover crop cultivation is a long-established pattern of continuous farming.It is of great significance to carry out research on ecosystem services and values of cover crop intercropping farmland for scientifically understanding the value of farmland ecosystem services,promoting the transformation of ecological asset values,and promoting the realization of ecological product values.The study adopted a combination of field experiments,laboratory analysis and value accounting,selected ryegrass,alfalfa and hairy vetch as cover crops,set up four treatments:maize monocropping（CK）,ryegrass and maize intercropping（Ryegrass-Maize）,alfalfa and maize intercropping（Alfalfa-Maize）and hairy vetch and maize intercropping（Hairy vetch-Maize）,to study the effects of different cover crops and maize intercropping on maize yield,soil nutrients and their associated invertases enzymes and greenhouse gas emissions,On this basis,the value of farmland ecosystem services in different planting modes is calculated,in order to provide a reference for exploring the generation mechanism of farmland ecosystem services and quantifying the value of farmland ecological services.The main conclusions are as follows:1.Intercropping can increase maize yield per unit of land area.Hairy vetch-Maize and Alfalfa-Maize could significantly increase maize yield per unit area（P<0.05）.2.Intercropping can improve soil nutrient supply capacity.It has an enhancing effect on soil soluble organic nitrogen,ammonium nitrogen,nitrate nitrogen,available phosphorus and available potassium.Hairy vetch-Maize and Alfalfa-Maize could significantly increase soil dissolved organic nitrogen contents,soil nitrate and ammonium nitrogen contents（P<0.05）.Hairy vetch-Maize treatments significantly increased soil available phosphorus and soil available potassium content（P<0.05）.3.Intercropping increased soil enzymes activity.Hairy vetch-Maize and Alfalfa-Maize significantly increase enzyme activities related to nitrogen conversion（P<0.01）.Alfalfa-Maize significantly increase soil peroxidase enzyme activity（P<0.05）.The activity of polyphenol oxidase in Hairy vetch-Maize is significantly higher than that in CK（P<0.05）.4.The impact of intercropping on GHG emissions is influenced by the type of cover crop.Ryegrass-Maize significantly reduces soil CO₂ emissions（P<0.05）.Intercropping of cover crops and maize significantly reduce soil N₂O cumulative emissions（P<0.05）.5.Intercropping improves the value of farmland ecosystem services.The ecosystem services of different treatments are sorted from highest to lowest:Alfalfa-Maize>Ryegrass-Maize>Hairy vetch-Maize>CK,intercropping increased the overall ecosystem service value due to nutrient cycling value increasing.In conclusion,at the initial stage of conversion from monoculture maize to legume cover crop intercropping with maize,some indicators of available nutrients and enzymes in soil fertility are slightly improved,maize yield per unit area is increased,and farmland ecosystem service value is increased.