| Biochar,as a soil conditioner,is increasingly recognized and accepted by scientific community.Currently,the research on soil amendments by biochar mainly focuses on the tropical,subtropical and temperate acidic soils,while there are few researches on physical and chemical properties of saline-alkali soil,soil microenvironment and crop growth.Based on this point,the effects of biochar application in saline-alkali soil inter-field scale was studied in order to clarify the effects of biochar application on the physical and chemical properties,nutrition indexes,soil micro-environment of saline alkaline soil and soybean growth,so as to provide a reference for the utilization of biochar in the agriculture of saline-alkali soil.This study was conducted in the Experimental Base of College of Agricultural,Heilongjiang Bayi Agricultural University.Biochar derived from corn straw was applied at four loading rates: 0 t / hm2(B0),32.5 t / hm2(B1),65 t / hm2(B2)and 130 t / hm2(B3)(w/w),and applied at one time.Soil physical index,chemical index,nutritional index,soil enzyme index,and plant photosynthetic physiology,growth and development,and yield index were measured respectively.The changes of soil microbial diversity were studied by traditional dilution plate cultural method,Biolog-ECO microplate method and Illumina Miseq sequencing,respectively.The results are as follows:Biochar application significantly reduced the bulk density of saline-alkali soil,increased the total porosity,the saturated water holding capacity and the measured field water holding capacity,increased the infiltration capacity of saline alkali soil at the unstable and stable infiltration stage,and the infiltration rate increased significantly with the increase of biochar application.After the biochar was applied into the alkaline soil,the soil EC and p H showed a dynamic trend with the development of soybean growth and increase of seasonal rainfall.Biochar had little effect on the soil p H in the early growth stage of soybean,and the p H decreased with the increase of biochar loading rates in the later growth stage.Biochar also significantly increased the CEC level of soil and decreased soil ESP.The "V" curve of field electrical conductivity(EC)of Soda saline-alkali soil amended with biochar was proposed for the first time in this study,which enriched and perfected the mechanism of biochar regulating Soda saline-alkali soil.B2 and B3 treatment significantly increased the total organic carbon content and total nitrogen content at different soybean growth stage.At the same time,the soil C/N ratio increased with the increase of biochar loading rates.Among them,the soil C/N ratio of B3 treatment increased by 39%,27.8%,24.2%,27.9% and 20.4% respectively compared with the control at five growth stages.The application of biochar increased the NH4+-N and decreased NO3--N content of the tested soil,decreased the content of available nitrogen,and increased the content of available phosphorus and available potassium in the soil.Four key enzymes showed different trends in the whole growth stages of soybean.The difference of alkaline phosphatase activity between sowing and full bloom stage was more significant than that between podding and ripening stage.The soil invertase activity of B3,B2 and B1 treatment increased by 20.89%,19.40% and 9.75% respectively compared with the control at the early bloom stage,and increased by 29.42%,18.61% and 12.73% respectively at the full bloom stage.The activities of soil invertase increased with the increase of biochar application,and the effects of different biochar treatments on soil urease and catalase activities were different in different growth stages of soybean.Biochar application increased leaf area index,photosynthetic potential and dry matter accumulation of soybean.The application of biochar significantly increased the number of pods per plant,the number of seeds per plant,the weight of 100 seeds and the yield of seeds.The B2 treatment yield the highest seed yield,while the seed yield and biomass yield of B3 treatment decreased slightly.The yield showed B2> B3 >B1>B0,and increased by 11.01%,7.57% and 5.47% respectively compared with the control.The application of biochar in saline-alkali soil increased the relative abundance of bacterial and affected the composition of soil bacterial community.Among them,Proteobacteria?Acidobacteria?Gemmatimonadetes?Actinobacteria?Chloroflexi?Bacteroidetes Nitrospirae are are playing the role of predominant.Among them,Proteobacteria has the highest relative abundance,followed by Acidobacteria?Gemmatimonadetes and Actinobacteria.The application of biochar increased the microbial activity of cultivated soil and the number of beneficial bacteria in bacterial community(e.g.,Pseudomonas and Gemmatirosa).And Rokubacteria were detected for the first time in biochar treated soda saline-alkali soil in our study,Rokubecteria is a monophyletic strain with large genome and high GC content,and it was reported as“Novel soil bacteria possess diverse genes for secondary metabolite biosynthesis.”This study confirmed that biochar has the potential to improve the plant growth and soil condition in poor alkaline soil.The biochar can be applied to the high p H saline-alkali soil as a soil conditioner,improve the physical,chemical and nutritional characteristics of the alkaline soil,especially the soil hydraulic properties,improve the soil microenvironment,and then improve water and nutrient use efficiency,and then improve the yield of crops.At the same time,special attention should be paid to the negative effects of excessive application of biochar in alkaline soil,which should be considered in the application process. |
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