| The two-maturing area of the Yubei Plain is an important grain-producing area in China.The crop planting in this area adopts the single-crop mode of summer maize-winter wheat twice a year,and the long-term use of chemical fertilizers leads to acidification and fertility decline of soil structure.Such problems have limited the production efficiency of the land.Rotation has the effect of improving soil physical and chemical properties and improving land production efficiency.However,the mechanism of change in the physical and chemical properties of soil is still insufficiently understood.Therefore,in this study,the physical and chemical properties and microbial community structure of rhizosphere soil and non-rhizosphere soil under four rotation patterns and eight conventional planting patterns were determined by conventional methods of soil physical and chemical properties and high-throughput sequencing of soil microbial communities.The comparative study on community diversity has provided a theoretical basis for the construction of land productivity restoration and rational cultivation model system in the main grain crop production areas in the two-middle area of the northern Henan Plain.The main results are as follows:1.Comparing the soil physical and chemical properties under the four rotation patterns,it was found that the soil organic matter content decreased gradually with the increase of planting years,and the soil organic matter content rotation was significantly higher than that of single cropping.The total nitrogen content in the soil increased with the increase of planting years.For soil pH,the soil pH of the rotation was lower than that of the single crop;from the analysis of the trend of the five sample data from 2016 to 2018,both farming models showed a “W” pattern;In terms of changes in total phosphorus content,the trend of change is opposite to that of soil pH,presenting an "M" shape.Among them,the soil C/N in the four rotation modes was significantly higher than 25:1.2.In order to understand whether the changes in soil physical and chemical properties under different rotations are caused by the effects of rotation on soil microbial community structure and diversity,we studied soil microbes under four different rotation patterns.The results showed that the number of bacteria and fungi OTU in the soil samples under rotation was 79376 and 6500,respectively,and the number of soil bacteria and fungi OTU under single crop was 74614 and 6144,respectively,so the bacteria in the soil samples were rotated.The number of fungi OTUs was significantly higher than that of monoculture,and the number of bacteria in soil samples showed a curve change with the year of planting.In different planting methods,except for wheat,the number of bacteria in soil samples in no-tillage mode was significantly higher than that in normal farming in peanut,corn and soybean fields.The sequencing results also showed that the dominant bacterial flora in the obtained microbial community was Proteobacteria(about 25%),Fusarium(about 20%),Actinobacteria(about 16%),and Acid Bacillus(about 14%),the content of these four dominant bacterial flora is about 75%.The dominant fungal flora is Ascomycota,which accounts for more than 65% of the fungal community.In order to understand the relationship between the physical and chemical properties of soil and the relationship between microbial communities,the trend of soil physical and chemical properties and microbial community change trends under different rotation patterns showed that the change trend of soil pH was the same as that of bacteria and fungi OTU.,showing a "W" type,and the total phosphorus content of the soil is opposite to that of the "M" type.3.In order to analyze whether crop root exudates affect soil physical and chemical properties,we analyzed the physical and chemical properties of rhizosphere soil and non-rhizosphere soil under 8 different planting patterns.The results showed that except for the pH value of soil,the contents of soil organic matter,total nitrogen and total phosphorus were significantly higher than that of non-rhizosphere soil.Among them,soil C/N was significantly higher than 25:1 in 8 different planting modes.4.In order to understand whether root exudates affect soil microbial community diversity,we studied the microbial community diversity of rhizosphere soil and non-rhizosphere soil under 8 different planting patterns.The results showed that the number of bacteria and fungi OTU in rhizosphere soil was 48724 and 4897,respectively,and the number of bacteria and fungi OTU in non-rhizosphere was 38656 and 4431,respectively.Therefore,the number of bacteria and fungi OTU in rhizosphere soil was significantly higher than that in non-rhizosphere.earth.In addition,the effects of root exudates of different crops on microbial communities were different.For example,the number of non-rhizosphere soil bacterial communities planted under normal tillage was significantly higher than that of other crops;the non-root soil bacterial community of maize under no-tillage mode The number is significantly higher than other crops.Comparing soil type,organic matter,pH value,total nitrogen and total phosphorus content and microbial community change trends under different planting patterns,soil organic matter,total nitrogen,total phosphorus and soil microorganisms were found in addition to soil pH.Diversity is higher than non-rhizosphere soil.5.In addition,we screened and identified the dominant microorganisms in the study area.After 16 S rDNA sequencing and phylogenetic tree analysis,a strain of Stenotrophomonas maltophilia was initially obtained.The Congo red hydrolysis cycle method showed that the strain had the ability to decompose cellulose. |
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