| In view of the problems such as single planting patterns,serious soil desertification,decreased soil nutrients and fertility,and farmland ecological deterioration in Horqin Sandy Land,this paper conducted a localization experiment to improve soil quality and agricultural ecological function in this area.Four planting patterns were set as peanut-maize rotation(P-MR),maize-peanut rotation(M-PR),maize continuous cropping(MC)and peanut continuous cropping(PC),respectively.To study the spatial and temporal changes of soil physical and chemical properties,microbial biomass,soil culturable microorganisms,microbial community structure and diversity in surface soil(0-20cm)and subsurface soil(20-40cm)in different growing seasons under different planting patterns.the results are as follows:(1)Different planting patterns had no significant effect on soil p H in 0-20 cm soil layer.In the20-40 cm soil layer,the p H of the maize-peanut rotation and peanut continuous cropping treatments was lower,and the soil p H value decreased due to peanut planting.Different planting patterns significantly affected soil nutrient content.The contents of soil organic matter,total nitrogen,available nitrogen,total phosphorus,available phosphorus,total kalium and available kalium in rotation pattern were higher than those in continuous cropping pattern.Specifically shown as MPR>P-MR>MC>PC.In terms of vertical soil structure,the overall soil nutrients of the four planting patterns showed a downward trend,and the plough layer(0-20cm)was higher than the plough pan(20-40cm),and the soil nutrients showed surface aggregation.(2)Different planting patterns had significant effects on microbial biomass.The contents of MBC,MBN and MBP in maize-peanut rotation treatments were higher than those in maize-peanut rotation treatments.Seasons had significant effects on soil microbial biomass.The MBC content of the four planting patterns were spring >autumn> summer.MBN content was summer >autumn>spring.The content of MBP was the highest in spring.In terms of soil vertical structure,MBC,MBN and MBP of the four planting patterns all decreased with soil depth deepening.(3)The number of soil culturable microorganisms under the four planting modes showed Bacteria >Actinomycetes>fungi.The contents of culturable bacteria,fungi and actinomycetes in spring,autumn and 0-20 cm soil layer were higher than those in continuous cropping pattern,while the contents of culturable bacteria,fungi and actinomycetes in other treatments and 20-40 cm soil layer were higher than those in rotation pattern.Seasons had significant effects on soil culturable microorganisms.The changes of the content of culturable bacteria in the four planting patterns was spring>summer>autumn.The fungi content changed was spring>autumn> summer.The seasonal dynamics of actinomycetes were similar to those of fungi,with the highest variation in spring.In the vertical structure of soil,the number of three kinds of culturable microorganisms decreased along the vertical distribution under the four planting patterns,and the number of culturable microorganisms in the plough layer(0-20cm)was higher than that in the plough pan(20-40cm).Planting patterns changed the soil microenvironment.(4)Planting patterns changed soil microbial community structure.The microbial communities of P-MR,M-PR and MC treatments were significantly different from those of other treatments in spring.Microbial community structure in spring,summer and autumn treated by MC and PC was similar.The variation of soil microbial community diversity index under planting mode was greatly affected by season.Except that the diversity index of PC treatment was significantly lower than that of other treatments in summer,there was no significant change of diversity index among different treatments in different seasons(P>0.05).Compared with PC,rotation treatment,especially M-PR treatment,had higher diversity index.Maize-peanut rotation is beneficial to improve soil ecological environment. |
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