Effects of multiple cropping green manure practices and nitrogen fertilization regimes on soil organic carbon and wheat yield after wheat
[Objective]In view of the problems of long-term continuous cropping and irrational fertiliza-tion of wheat crops in the Qinghai-Tibet Plateau,which lead to the reduction of soil organic carbon and crop yield,the effects of different green manure planting patterns and nitrogen fertilization systems on soil or-ganic carbon content and crop yield were investigated to provide a basis for soil sequestration in the experi-mental area.[Method]This study is based on the long-term positioning experiment set up at the experimen-tal station of the Academy of Agriculture and Forestry,Qinghai University in 2018.The experiment ad-opted a two-factor split-plot design,and two nitrogen fertilization systems were set up in the main plot.The total nitrogen fertilization rate was 180 kg/hm2,and spring wheat and green manure were divided into two systems.100%and 0%(N1),80%and 20%(N2),and three green manure patterns for multiple cropping af-ter wheat were established in the subplot:spring wheat-Vicia sativa(W-V),spring wheat-rape(W-R)and spring wheat-Vicia sativa×rape(W-VR);6 treatments in total.Soil samples in the ploughing layer(0~10 cm and 10~30 cm)were collected after the spring wheat harvest in 2020 and 2021,and soil organic car-bon and its components were determined.[Result]There was a significant difference between N2 and N1 in the 0~30 cm soil nitrogen application system(P<0.05),and the contents of soil organic carbon,soluble or-ganic carbon,hot water extraction organic carbon and easily oxidizable organic carbon were increased by 4.7%in N2 compared with N1,2.9%,7.9%and 4.5%,the yield of wheat grain increased by 12.1%.The content of organic carbon in the 0~30 cm soil layer of different green manures after wheat was significantly different(P<0.05),and the soil organic carbon content of W-VR was higher than that of W-V and W-R.content increased by 7.6%and 15.1%,soil soluble organic carbon content increased by 5.6%and 10.80%,soil hot water extraction organic carbon content increased by 4.9%and 15.7%,soil easily oxidiz-able organic carbon content increased by 7.5%and 13.6%,and grain yield increased by 4.9%and 11.1%.The interaction between wheat post-wheat green manure mode and nitrogen application system has a sig-nificant effect on soil organic carbon content,and W-VRN2 has a higher level of soil organic carbon,hot wa-ter extraction organic carbon and easily oxidized organic carbon than traditional planting mode W-VN1 re-spectively increased by 12.6%,13.0%and 12.5%,wheat grain yield increased by 17.7%.[Conclusion]Mixed sowing of Vicia sativa and rapeseed after wheat combined with 20%nitrogen application of green manure can effectively increase soil organic carbon content and increase wheat grain yield,which is a reason-able green manure planting pattern and nitrogen application system in the Qinghai-Tibet Plateau.
spring wheatgreen manureplanting patternnitrogen fertilization regimeorganic carbon