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Effects Of Different Winter Planting Patterns On Soil Physical And Chemical Properties And Microbial Diversity In Double Cropping Rice Fields

Posted on:2021-05-28Degree:MasterType:Thesis
Country:ChinaCandidate:P ZhangFull Text:PDF
GTID:2480306302488314Subject:Ecology
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Winter cropping plays an important role in the utilization of natural resources.The planting of green manure is conducive to the maintenance of soil quality.The planting of cash crops is conducive to the increase of farmers' income.The optimization of the planting patterns fully reflects the effective utilization of light,temperature,water and heat resources,and improves the soil ecology and guarantees food production.Soil fertility can ensure the healthy growth of crops,which is reflected in the biological processes of soil physical structure,chemical nutrients,and microbial metabolism.In view of this,based on the field experiments and due to the limitations of the traditional planting patterns in the Middle Reaches of the Yangtze river,this study set up different winter planting patterns to study the effects of five winter planting patterns on soil aggregates,organic carbon pool,organic carbon mineralization characteristics and microbial community in paddy soil,and comprehensively analyzed the relationships among soil physics,chemistry and microbial community under different planting patterns,aiming at revealling the effects of long-term different planting patterns on soil organic carbon pool and microbial community,improving soil carbon fixation capacity and guaranteeing food security in the paddy field,which can provide scientific basis for formulating reasonable planting patterns to maintain sustainable soil productivity.The main conclusions are as follows:(1)In terms of rice yields,based on the annual average yield,it can be seen that the yield growth ranges from 0.88% to 3.18%,the planting pattern of winter garlic and winter crop rotation performed better(P<0.05).(2)In the aspect of soil physical properties,through the comprehensive analysis of0?30cm soil layer,it is found that the soil aggregate content(>2mm)was dominant(the highest),followed by <0.053 mm,while the soil aggregate content of 1?2mm,0.5?1mm,0.25?0.05 mm,0.053?0.25 mm was similar;the mean weight diameter(MWD)and geometric mean diameter(GMD)of water-stable aggregates in paddy fields were increased by all winter cultivation treatments.The MWD of winter rape treatment,winter rotation treatment and winter Chinese milk vetch treatment were increased by 21.50%,21.16% and16.32% respectively(P<0.05).GMD of winter rape treatment and winter rotation treatment increased by 83.31% and 62.50%,respectively,compared with that in winter fallow treatment(P<0.05).Different planting patterns significantly reduced the fractal dimension of soil water stable aggregates(P<0.05),which was helpful to maintain the stability of soil structure;the change of soil bulk density by different planting patterns was not significant(P>0.05),but their long term planting reduced the soil bulk density to a certain extent,and the soil bulk density increased with the increase of soil depth.(3)In terms of soil fertility,different winter planting patterns have positive effects on the improvement of soil total nitrogen in 0?30cm soil layer,soil microbial biomass carbon,easily oxidized organic carbon and soluble organic carbon content were increased in a certain degree;Secondly,winter planting patterns are conducive to the improvement of soil organic carbon content in paddy field,among which continuous cropping pattern of winter garlic and rotation have an effect on the accumulation of soil organic carbon.The most significant is that the long-term winter rotation planting mode can significantly improve the accumulated mineralization amount and rate of soil organic carbon;Each winter planting mode slightly reduced the accumulated mineralization rate of soil organic carbon and beneficial to the increases of soil carbon fixation capacity.(4)In terms of soil microorganism,compared with winter fallow CK,each winter planting mode is beneficial to the increase of species diversity in the rhizosphere of paddy field,among which the difference between winter garlic and winter fallow treatment is significant(P<0.05);In terms of soil community diversity index,winter planting modes significantly increased the Shannon and Simpson indexes of soil(P<0.05),but in the community richness index,there was no significant difference in the indexes of Chao 1 and ACE(P>0.05).
Keywords/Search Tags:double cropping rice field, rotation, soil organic carbon, organic carbon mineralization, soil aggregate, bacterial diversity
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