Effects Of Crop Rotation Combined With Fertilization On Soil Organic Carbon Components And Related Properties

The potential fertility of chernozem is relatively high.Hulunbeir is dominated by large scale mechanized farming operations.The disturbance of chernozem is relatively large,and the structural pressure of arable land grain supply gradually increases.This paper uses the common farming structure of Rapeseed-Wheat rotation and new cultivation structure Bean-Oat rotation were used as a comparison to compare the effects of two cropping patterns on crop yield,soil organic carbon composition,and soil properties.There were three kinds of fertilization conditions,including compound fertilizer,chemical fertilizer and no fertilizer,and four crops of rapeseed,wheat,bean and oat,and two cropping patterns.The results showed that:1.In the two rotations model,crop rotation combined with application of organic compound fertilizer can significantly increase crop grain yield.In the rapeseed-wheat rotation system,under the same fertilization conditions,rotation yield was increased by 27.52%-80.44% compared to continuous cropping,and wheat was treated with organic compound fertilizer,which was 38% higher than non-fertilizer treatment.In the Bean-Oat rotation system,grain yields were all expressed as organic compound fertilizer> chemical fertilizer> no fertilizer due to different types of fertilization.After rotation,organic compound fertilizer treatment significantly increased the yield by 14.3%-39.4%.2.Rotation combined with organic compound fertilizer can significantly increase the content of soil organic carbon and its components.Both rotation patterns showed that organic carbon content was the highest in all agglomerations of organic compound fertilizer in rotation.Rotation of rapeseed-wheat rotation increased by 11.74% to 35.42% compared with continuous cropping,and the increase in Bean-oat rotation was 7.35%-16.06%.The change trend of light organic carbon in the light group was consistent with the trend of total organic carbon,both showing that: when the fertilization conditions were the same,the rotation pattern was higher than continuous cropping pattern;in the rotation pattern,organic fertilizer had the highest organic carbon content and the chemical fertilizer had the lowest content.The content of easily oxidized organic carbon in soil agglomerates was 1mm-2mm in the agglomerates.The combination of rotation and fertilization increased the content of easily oxidizable organic carbon in agglomerates.Microbial biomass carbon and soluble organic carbon basically showed that the content of fertilizer treatment was higher than that of no fertilizer treatment,and organic compound fertilizer could increase its content significantly,and the combination of organic compound fertilizer and rotation had the highest content.3.Rotation combined with organic compound fertilizer improves soil physical properties.In the rapeseed-wheat rotation model,soil macroaggregates increased significantly,with an increase of 8.48%-10.67%.Soil bulk density was significantly reduced in the two rotation modes,of which rapeseed-wheat rotation pattern had the largest decrease,reaching 19.77%.Rotation combined with fertilization can effectively increase the soil moisture content,organic compound fertilizer has the best effect,and can reduce soil water consumption of 80-100 cm after rotation,ensure the moisture content in deep soil,and improve soil drought resistance.4.Rotation combined with organic compound fertilizer can significantly increase the soil available nutrient content.The performance trends of alkaline N and available K were basically the same,that is,fertilization could increase the content of two available nutrients in soil,and the effect of organic compound fertilizer was more obvious.Among them,the increase of alkali-hydrolyzable nitrogen content in soil was the most significant under the Bean-oat rotation pattern,with an increase of 3.94%-39.66%.The trend of phosphorus content in soil under different cropping modes was different.In rapeseed-wheat rotation system,each treatment could increase its content after fertilization.However,the content of available phosphorus in soil after the application of manure with Bean-Oat rotation and mango bean continuous cropping was similar.There are different degrees of reduction.5.Application of chemical fertilizers significantly affected soil sucrase activity.The rotation pattern of the two groups showed that the soil invertase treatment had the lowest sucrase activity,while the application of organic compound fertilizer could significantly increase soil sucrose activity.The invertase activity after fertilizer increased by 2.23%-24.08% in the Bean-Oat rotation.Urease and catalase showed different trends in different crops,tillage methods and fertilization types,but applying organic compound fertilizer under rotation mode could significantly increase the activities of the two enzymes.