C And N Characteristics Of Desert Steppe Soil Under Different Caragana Intermedia Stubble

Caragana intermedia is a legume shrub widely planted in Ningxia desert steppe,because it is an excellent coarse feed for livestock,the utilization of its stubble can not only supplement the coarse feed for livestock,but also the main measure of regeneration and rejuvenation of Caragana intermedia.Under the background of global climate change,it is of great significance to explore the effects of Caragana intermedia stubble on soil carbon and nitrogen characteristics in desert steppe for the development of grassland and livestock industry and scientific management of desert steppe.In this study,desert steppe of Different Caragana intermedia stubble styles in Yanchi County,Ningxia was taken as the research object.The characteristics of soil,soil microorganisms and soil extracellular enzymes C and N and their internal correlations were analyzed in the artificial Caragana intermedia forest with No stubble(WP),Stubble one belt with two belt no stubble(G2P1),Stubble one belt with one belt no stubble(G1P1),Stubble two belt with one belt no stubble(G1P2),All stubble(QP).The main conclusions were as follows:(1)There were significant differences in soil pH,bulk density,water content and electrical conductivity under different Caragana intermedia stubble(P<0.05).WP had the highest soil pH and bulk density,while QP had the highest soil water content and electrical conductivity.Soil bulk density,water content and electrical conductivity all increased with the soil layer decreasing.Soil pH and bulk density decreased with the increase of stubble amount,while soil water content and electrical conductivity increased with the increase of stubble amount.(2)Soil carbon and nitrogen in desert steppe were significantly different under different Caragana intermedia shrub stubble(P<0.05).Soil carbon and nitrogen contents QP and G1P1 in Caragana intermedia shrub forest were the highest,while soil CARBON and nitrogen ratio of QP and G1P1 were the lowest.The mean values of soil carbon and nitrogen in the study area were 5.80g/kg and 0.20g/kg,respectively,lower than the national average of 11.12g/kg and 1.06g/kg.There was no significant difference in soil soluble organic carbon among different stubble treatments(P>0.05),and SOIL readily oxidized organic carbon of G1P1 was the highest and WP was the lowest.The soil ammonium nitrogen in QP was the highest,and that in G2P1 was the lowest.The soil nitrate nitrogen in G2P1 was the highest,and the soil QP was the lowest.Soil carbon and nitrogen contents showed a low-high-low trend with the soil layer decreasing,and soil carbon,nitrogen,soluble organic carbon and nitrate nitrogen increased with the stubble amount increasing.(3)Soil microbial biomass carbon and nitrogen of desert steppe under different Caragana intermedia stubble were significantly different(P<0.05):The soil microbial biomass carbon of G1P1 was the highest,and the soil microbial biomass nitrogen of QP was the highest.There was no significant difference in soil microbial entropy carbon of different stubble modes(P>0.05).The soil microbial entropy nitrogen of WP was the highest,and the soil microbial biomass C:N of G2P1 was the highest.LAP,NAG,BG,AP,BG:NAG was highest in WP,G1P1,G2P1,WP,G2P1,respectively.Soil microbial biomass carbon,microbial biomass N,microbial entropy carbon and microbial entropy nitrogen all showed a decreasing trend with soil layer decreasing.Soil microbial biomass carbon,microbial biomass C:N,NAG,BG and BG:NAG increased firstly and then decreased with the increase of stubble amount.In terrms of extracellular enzymes,except AP,the other three extracellular enzymes were higher in G1P1.For AP,uneven stubble could maintain higher soil alkaline phosphatase activity.(4)The relationship between C and N characteristics of soil-microbe-extracellular enzyme showed that soil soluble organic carbon had a strong positive correlation with soil water content,electrical conductivity,nitrogen,ammonium nitrogen,microbial biomass nitrogen and NAG,indicating that soluble organic carbon could be used as a reference index in evaluating the soil of Caragana intermedia forest in desert steppe.The relationship between SOIL extracellular enzyme NAG and soil nitrogen was stronger than LAP,and BG was stronger than soil carbon content on the easily oxidized organic carbon,indicating that soil easily oxidized organic carbon is the organic carbon component affecting BG in the soil organic carbon pool.(5)In this study,G1P1 and QP significantly improved soil bulk density and pH,and increased soil water content,carbon and nitrogen content,storage and microbial biomass nitrogen in desert steppe under five cropping methods.Principal component analysis based on soil carbon and nitrogen characteristics showed that G1P1 treatment was the most beneficial to the preservation of soil properties in desert steppe among the five treatments.