| The farmland soil environment has been destroyed over the recent years because of excessive reclamation and inappropriate fertilizer.Consequently,the decrease of soil fertility has severely threatened the sustainable utilization of farmland soil.Due to excellent characteristics of diatom shale,such as abundant nanopore,super adsorption,diatom shale can improve soil environment and increase crop growth.Therefore,a rice experimental area of diatom shale was set up in this study.Diatom shale powder was applied with the first fertilization.There were four treatments in this experiment,0kg/hm~2(CK),150kg/hm~2(DS10),300kg/hm~2(DS20),600kg/hm~2(DS40).Soil samples were collected from rice rhizosphere at maturity stage.The soil physico-chemical properties and enzymes activities were determined.Illumina Miseq sequencing was used to study the effects of different doses of diatom shale on the abundance,diversity and structure of bacterial and fungal communities in rice rhizosphere soil.The relationship among diatom shale dosage,soil physical and chemical properties and soil microbial community was discussed in this study.This study provides a reference for rational application of diatom shale resources in agriculture.Main results are shown as follows:1.Soil pH value in the diatom shale treatments was decreased by 1.73%-6.14%compared to the CK treatment.Soil total nitrogen was increased by 20.69%-51.72%.Soil available nitrogen was increased by 25.05%-32.76%.Soil available potassium was increased by 19.05%-38.78%.Soil organic carbon in DS10 and DS20 treatments were increased by 46.21%and 32.94%compared to the CK treatment,respectively.Total phosphorus in DS10 and DS20 treatments were increased by 24.97%and 17.52%compared to the CK treatment,respectively.Available phosphorus in DS40 treatment was decreased by 20.34%compared to the CK treatment.Soil total potassium in all diatom shale treatments did not significantly change.2.After diatom shale application,soil dehydrogenase activity decreased significantly.Catalase activity did not change significantly.Sucrase activity was increased by18.03%-45.48%.Amylase activity was increased by 19.66%-37.06%.Cellulase activity was increased by 11.71%-169.49%.Soil urease activity increased by 21.31%and29.51%in DS10 and DS20 treatments,and decreased by 50%in DS40 treatments.Soil acid phosphatase activity increased by 24.05%in DS10 treatment,did not change significantly in DS20 treatment,and decreased by 19.59%in DS40 treatment.The soil enzyme and soil properties have some certain correlation.3.Compared with the CK treatment,the soil bacterial community richness index and diversity index after application of diatom shale decreased by 0.28%-1.02%and0.33%-1.96%,respectively.The soil fungi community richness index was decreased by7.98%-34.51%.The soil fungi community diversity index was increased by 20.14%in the DS10 treatment and decreased by 21.49%and 46.23%in the DS40 and DS20,respectively.Principal component analysis showed that diatom shale changed the structure of soil bacterial and fungal communities.Community composition analysis showed that the dominant phylum of soil bacteria after diatom shale application was Proteobacteria,Chloroflexi,Acidobacteria,Actinobacteria and Bacteroidetes,and the dominant phylum of soil fungi was Ascomycota and Basidiomycota.The relative abundance of Proteobacteria increased by 3.33%in DS40 treatment compared to the CK treatment.The relative abundance of Chloroflexi was increased by 3.64%-14.06%in diatom shale treatments.The relative abundance of Nitrospirae was increased by8.33%and 11.43%in DS10 and DS40,respectively.The relative abundance of Ascomycota increased by 24.77%in DS20 treatment,and decreased by 9.48%and17.32%in DS10 and DS40,respectively.The correlation analysis between species and environmental factors showed that soil available nitrogen,total nitrogen,total phosphorus and total potassium were significantly correlated with bacterial community composition,and soil available phosphorus and available nitrogen were significantly correlated with fungal community composition.These indicated that the change of soil bacterial and fungal community structure after diatom shale application occurred indirectly as a result of the alteration of soil physical and chemical properties. |
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