Effects Of Different Crop Rotation Patterns On Soil Physical Structure,Organic Carbon And Related Enzyme Activities In Alpine Mountainous Area Of Northern Shanxi Province

With the rising of global temperature,the research on soil carbon cycle has attracted much attention.How to effectively control the emission of greenhouse gases has been a research hotspot for many years.Under this background,in order to explore the effects of different rotation patterns on soil structure and organic carbon in Alpine mountainous areas of northern Shanxi,a field experiment was conducted in Datong,Shanxi Province from 2018 to 2019.The treatments were as follows: rape-buckwheat(RB),corn-buckwheat(CB),potato-buckwheat(PB)and oat-buckwheat(OB)rotation mode,buckwheat-buckwheat(BB)continuous cropping and leisure-leisure(FF)as control.The soil physical properties,aggregate composition and stability,soil enzyme activity and soil organic carbon were measured.The results show that:(1)Compared with continuous cropping,soil bulk density decreased and soil field water capacity increased after rotation,which increased the number and stability of soil aggregates,and improved the soil structure in the study area.4 kinds of crop rotation mode,the rape-buckwheat crop rotation mode significantly increases the 0-20 cm soil layer soil porosity and capillary porosity and field capacity,MWD and GMD,respectively increased by 33.48%,48.16%,50.77%,5% and 7%,20-40 cm soil capillary porosity and field capacity,R0.25,MWD,GMD value was also significantly increased by 51.34%,61.01%,8%,26% and 37%,increased most,the most beneficial to improve soil structure in the study area.(2)Compared with continuous cropping,the content of soil total organic carbon had no significant change,the content of soil oxidizable organic carbon increased,and the activities of soil invertase and amylase increased.>3 mm aggregate is the largest contribution carrier of soil aggregate organic carbon in the study area.The results showed that rape-buckwheat crop rotation mode can maintain relative stability of the soil total organic carbon content,and most significantly increased the easy oxidation of soil organic carbon content,the three periods of seedling,flowering and maturity,0-20 cm and 20-40 cm soil layer,in turn,has increased 43%,7%,9% and 35%,26%,15%,and the organic carbon content of different graded aggregate and > 3 mm size aggregate organic carbon and contribution rates also increased significantly.Potato-buckwheat rotation significantly increased soil invertase and amylase activities,followed by rape.In general,rape-buckwheat rotation mode is most conducive to improve the availability of soil organic carbon nutrients in the study area,but also conducive to the stability of organic carbon.(3)After comprehensive analysis and comparison,rape-buckwheat rotation mode was more conducive to the improvement of soil structure and the storage and fixation of organic carbon in the study area,which can be promoted and applied as an important rotation mode in the study area.