Effects Of Different Greenhouse Vegetable Production Patterns On Soil Fertility And Microbial Diversity

Studying the effect of different production patterns on the soil microbial community structure and diversity in the soil ecosystem of the vegetable field is of great significance for maintaining soil fertility and soil health.In this study,the long-term experiment of organic vegetables in solar greenhouses established in 2002 was used as a platform to study the effect of different production patterns on soil fertility and microbial diversity by measuring soil moisture,pH,carbon,nitrogen and phosphorus,enzyme activity,microbial biomass carbon and microbial diversity.And then,the mechanism of different patterns of production on soil fertility and soil microbial community structure and diversity was explored.The main conclusions are as follows:(1)Organic and low-input production patterns could reduce pH value of soil in vegetable fields,increase soil moisture content and total carbon,nitrogen and phosphorus,and significantly increase soil organic carbon,inorganic carbon,and available phosphorus,compared to conventional production pattern.The organic production pattern and the low-input production pattern increased the ammonia nitrogen content of the available nitrogen,but reduced the nitrate nitrogen content.(2)Under the three production patterns,the soil catalase activity in both periods was highest under the conventional production pattern,and was lower under the low-input production pattern and the organic production pattern.Soil urease activity and protease activity responded differently to three different production patterns in different growth stages of celery.In October,organic and low-input production patterns could significantly increase soil urease activity but reduce soil protease activity.In the late growth period of celery in December,the organic production pattern and low-input production pattern could significantly improve soil protease activity,but it was not significant for the improvement of soil urease activity.(3)Phospholipid fatty acid biomarkers of 33 soil microorganisms were detected in soil samples of three production patterns using phospholipid fatty acid(PLFA)technology.The total PLFA content of bacteria,PLFA content in Gram-positive bacteria and Gram-negative bacteria in bacteria,and PLFA content in actinomycetes were the highest in the organic production pattern,followed by the low-input production pattern,and the lowest in the conventional production pattern.However,the response of fungi to different patterns of production did not have obvious rules.Under the three patterns of production,soil microbial biomass carbon(MBC)and soil microbial PLFA total amount were higher in the organic production pattern than in the low-input production pattern than in the conventional production pattern.DNA high-throughput sequencing of soil microorganisms showed that 30 phyla of bacteria were detected at the phylum level.For the three patterns of production,there are six major dominant phyla,of which the relative abundance of Proteobacteria,Acidobacteria,and Bacteroidetes is relatively high,followed by the Actinobacteria,Chloroflexi and Gemmatimonadetes,and these six types of microorganisms account for about 95% of the relative abundance of total microorganisms.Overall,organic and low-input pattern are more conducive to increasing the abundance of Bacteroidetes,Actinomyces and Green Bacteria,while the three patterns of production have no significant effect on the abundance of Proteobacteria and Acidobacteria.At the classification level,there are 67 strains in the metagenomic sample.Under the three production patternls,the main dominant strains are Alphaproteobacteria,Gammaproteobacteria,Sphingobacteriia and Blastocatellia strains,and these four classes of microorganisms account for 40%-60% of the total microbial abundance,and there are significant differences in response to different soil layers at different times and different production patterns.Alpha diversity analysis of high-throughput DNA sequencing data showed that in the early growth stage of celery in October,the trend of the Chao1 and ACE richness indexes,and Shannon diversity index of the microbial community were the highest in the low-input pattern;he patterns of organic and conventional production followed;in December,there was no significant difference between the three indexes in different production patterns.(4)The correlation between soil microbial community,soil environmental factors and soil enzyme activity was analyzed by using IBM SPSS Statistics 22.0 software and Canoco 4.5 software.The results showed that the soil urease activity and the soil total C,N,and P,total organic carbon,available phosphorus,water content,and microbial biomass carbon were positively correlated;soil protease activity was positively correlated with soil nitrate nitrogen and total av+ailable nitrogen,and negatively correlated with soil pH;There is a significant negative correlation between soil catalase activity with soil nitrate nitrogen and total available nitrogen,and a significant positive correlation with soil pH.The total PLFA content of bacteria,PLFA content of Gram-positive bacteria and Gram-negative bacteria,PLFA content of actinomycetes and fungi,with soil available P,total available nitrogen,total organic carbon,and soil water content Significantly positively correlated,significantly negatively correlated with pH and catalase activity.The correlations between different microbial groups and soil physicochemical properties at the level of the phyla were significantly different,among which Proteobacteria,Bacteroidetes,and Letscibacteria were closely related to soil physicochemical properties and enzyme activity,and each microbial group and soil hydrogen peroxide.The correlation of soil catalase activity was the most significant,followed by soil urease activity,and there was almost no significant correlation with soil protease activity.