Effects Of Biochar And Arbuscular Mycorrhizal Fungi On Alfalfa Growth And Soil Chemical Properties In Different Saline And Alkaline Land

Planting crops in saline-alkali soils is an important measure for the sustainable use of land resources and an urgent issue to improve and restore of global ecosystems.Biochar（BC）mainly uses crop straws and rice husks as raw materials,it is an organic material that not only realizes resource reuse,but also improves the structure of the soil,reduces environmental and groundwater source pollution and increases plant biomass.Arbuscular mycorrhizal fungi（AMF）can mutually symbiotic with plant roots,and promote the absorption and utilization of nutrients such as water and nitrogen and phosphorus in host plants.However,the current research reports are relatively few that focus on improving the yield and quality of crops in saline-alkali land and effectively improving the soil through the synergy of rhizosphere microbial inoculum inoculation and organic material addition.In this study,the surface saline-alkali soils of farmland from Yinchuan,Ningxia and Dongying,Shandong were used as the test soil,the test plant was alfalfa（Medicago sativa L.cv.‘Zhongmu No.3’）,the pot experiment was conducted with biochar（corn stalk as raw material）and rhizosphere symbiotic microorganism AMF as experimental treatment factors.The research content includes two parts:Experiment（1）:Effects of AMF and biochar on alfalfa growth and soil physical and chemical properties in saline-alkali land of Yinchuan,Ningxia province.This experiment soil（unsterilized and sterilized（S））,AMF（not inoculated with AMF and inoculated with AMF）,and biochar（not added with biochar and added with 2%（w:w）biochar）.There were a total of eight treatments（CK,BC,AMF,AMF+BC,S,S+BC,S+AMF,S+AMF+BC）,with 3 repetitions for each treatment.The main test results are as follows:1.Whether the soil was sterilized,The biomass of alfalfa significantly increased in BC treatment and BC+AMF treatment（P<0.05）,but inoculation of AMF alone had no significant effect on the alfalfa biomass.2.Under unsterilized soil conditions,the plant total nitrogen concentration and nitrogen uptake increased in BC treatment and BC+AMF treatment,and the total phosphorus concentration of plants significantly increased with the adding biochar（P<0.05）.The total phosphorus concentration of plant roots significantly increased in BC+AMF treatment（P<0.05）;the nitrogen concentration of shoots inoculated with AMF significantly decreased（P<0.05）,but the nitrogen and phosphorus concentration of plant roots significantly increased（P<0.05）.After soil sterilization,the root nitrogen concentration and nitrogen absorption increased in each treatment;and the total phosphorus concentration of roots in each treatment（except S treatment）significantly increased（P<0.05）.3.The pH and electrical conductivity（EC）of the soil were reduced in each treatment.The NH4+-N and NO3--N concentration in soil significantly decreased（P<0.05）in BC treatment;the NH4+-N concentration in soil significantly increased（P<0.05）in BC+AMF treatment,which had no significant effect on NO3--N concentration in soil;the concentration of NO3--N in soil increased significantly（P<0.05）after inoculated with AMF,but the concentration of available phosphorus significantly decreased（P<0.05）.Experiment（2）:Effects of AMF and biochar on alfalfa growth and soil physical and chemical properties in the saline-alkali land of Dongying,Shandong province.The experiment design is the same as experiment（1）,the main test results are as follows:1.Under unsterilized soil conditions,plant biomass increased in BC treatment and BC+AMF treatment compared with control treatment,and the increase effect of BC+AMF treatment was significant（P<0.05）;after the soil was sterilized,the plant biomass was significantly reduced（P<0.05）,and the biomass above the ground inoculated with AMF was significantly increased（P<0.05）.2.Under the condition of unsterilized soil,the concentration of nitrogen and phosphorus in plant roots was significantly reduced in the inoculation of AMF only（P<0.05）,the absorption of nitrogen and phosphorus in plant roots was significantly increased in the addition of biochar only（P<0.05）,and the concentration of total phosphorus in plant overground was significantly increased（P<0.05）in BC+AMF treatment.After soil was sterilized,the total nitrogen concentration of plant roots significantly reduced in BC treatment（P<0.05）,and the nitrogen and phosphorus uptake of plants significantly increased with the inoculation of AMF（P<0.05）.The plant total phosphorus concentration significantly increased in BC+AMF treatment（P<0.05）,but decreased root total nitrogen concentration（P<0.05）.The effect of inoculating AMF alone on the increase of plant phosphorus uptake was significantly higher than that of adding biochar treatment（P<0.05）.3.There was no significant difference in the NH4+-N and NO3--N concentration in soil under the condition of non-sterilization.After soil was sterilized,the NO3--N concentration in soil in AMF treatment was significantly higher than in BC treatment（P<0.05）.The NO3--N concentration in soil was significantly increased in S treatment（P<0.05）,while that in other treatments was significantly decreased（P<0.05）.4.Under unsterilized soil conditions,the available phosphorus concentration in soil significantly increased in BC+AMF treatment（P<0.05）.After soil was sterilized,the available phosphorus concentration in soil significantly increased（P<0.05）except S treatment,and BC+AMF treatment>BC treatment>AMF treatment.