Effects Of Long-term Apply Organic Fertilizers On Physicochemical Properties And Microbial Community Of Tobacco Planting Soil

At present,the problem of soil degradation caused by continuous overuse of chemical fertilizer and single continuous cropping model in tobacco production has seriously affected the production of high quality tobacco in Hubei tobacco area.The application of organic fertilizer has achieved remarkable success in enhancing soil fertility and improving crop yield and quality.However,there are different results caused by significant differences in production process,element composition and nutrient content of different organic materials.Therefore,based on a long-term experiment of organic fertilization(2013—2020)in Baiyang Town,Lichuan City,Hubei Province.We set three organic fertilization pattern: Commercial organic manure(CFM1),farm manure(CFM2)and green manure(CFM3)with the conventional chemical fertilizer(CK)as the control to analyze changes of soil physicochemical and biological properties to provide a technical support for the conservation of tobacco-planting soil in Hubei Province.The main findings are as follows:1.Long-term application of commercial organic fertilizer significantly increased soil p H value,reduced soil bulk density and improved aggregate stability.The content of alkali-hydro nitrogen of three organic fertilizer was equivalent to that of chemical fertilizer treatment,while the content of available potassium increased by8.8%～14.2%.The content of soil available phosphorus in chemical fertilizer was equivalent to that of farm manure,but increased by 20.1% and 14.6% compared with that of commercial organic manure and green manure treatments.The content of available phosphorus and potassium in each treatment showed an upward trend in the in-situ time.2.There has been a general uptrend of soil organic content in commercial organic fertilizer and farm manure treatments with the increase of in-situ time,which increased by 4.4% and 4.0% respectively compared with chemical fertilizer treatment.While the green manure treatment had no significant effects.Compared with chemical fertilizer treatment,the application of farm manure significantly increased the content of soil microbial biomass carbon and labile organic carbon,which was 21.0% and14.1% higher than that of chemical fertilizer treatment.The application of commercial organic fertilizer also significantly increased the content of mid-and highly labile organic carbon in soil.In addition,the application of organic fertilizer could promote the accumulation of humus in soil,which was 7.0%～28.9% higher than that of chemical fertilizer treatment.Compared with green manure,commercial organic fertilizer and farm manure treatments also promoted the accumulation of humic acid in soil.Humic acid FTIR spectrum showed that the application of organic fertilizer increased the aromatic substances of humic acid,which was beneficial to the stability of humic acid structure.3.Compared with chemical fertilizer treatment,three kinds of organic fertilizer significantly increased the content of amino sugar nitrogen in soil.In addition,commercial organic fertilizer also increased the content of acid-hydrolyzed ammonia nitrogen and amino acid nitrogen in soil,and farm fertilizer significantly increased the content of amino acid nitrogen in soil.The proportion of soil acid-hydrolyzed organic nitrogen to total nitrogen was 73.3% to 82.5%,and the proportion of commercial organic fertilizer and farm fertilizer was lower than that of chemical fertilizer treatment,which was mainly caused by the decrease of the proportion of acid-hydrolyzed unknown nitrogen.4.The microorganisms carbon utilization ability in prosperously growing stage was higher than those of root-extented,maturing and harvested stages.Compared with CK treatment,the average well color development(AWCD)of commercial organic fertilizer and farm manure treatments significantly increased by 22.0% and31.0% respectively,15.2% and 18.0% of Mclntosh diversity index in root-extented stage.AWCD and functional diversity indices of CFM1 treatment in prosperously growing stage were significantly higher than others.Correlative analysis showed that soil microbial activity and functional diversity have a significantly positive correlation with p H.In addition,the content of available potassium,mid-and highly labile organic matter,acid-hydrolyzed ammonia nitrogen and amino acid nitrogen were also positively correlated with microbial functional diversity.5.16 S r RNA sequencing analysis suggested that the application of commercial organic fertilizer and farm manure could improve the diversity and richness of soil bacteria,and the composition of soil bacterial community was different in three kinds of organic fertilizer treatments.Commercial organic fertilizer significantly increased the relative abundance of bacteria such as Gemmatimonas,Arthrobacter,Nitrolancea and Sphingomonas,farm manure significantly increased the relative abundance of Gemmatimonas,and chemical fertilizer and green manure treatments significantly increased the relative abundance of bacteria such as Chujaibacter,Rhodanobacter,Bryobacter and Acidothermus.Correlation network analysis showed that these bacteria were the key species in the microbial network.At the same time,the microbial network of commercial organic fertilizer and green manure treatment was more close and stable.6.The yield of three kinds of organic fertilizer treatments increased by11.2%～13.1% compared with chemical fertilizer treatment,among which the commercial organic fertilizer treatment was the highest.The output value increased by 5.4%～12.5% compared with chemical fertilizer treatment,and the farm manure treatment was the highest.7.In conclusion,commercial organic fertilizer treatment could successfully improve soil fertility and microbial communities.Therefore,"chemical fertilizer combined with commercial organic fertilizer" is recommended as the main fertilization measure for the conservation of tobacco planting soil in this area.