Effects Of Long-term Application Of Organic And Inorganic Fertilizars On Microbial Community In Rice Wheat Rotation System

The use of organic compost combined with certain doses of inorganic fertilizer can enable balanced fertilization under intensive farming conditions,but little is known about how these fertilization practices affect the properties of the soil and the microbial communities in arable ecosystems.In this study,a field trial of a rice-wheat cropping system was established to examine the effects of 8 years of fertilization with inorganic fertilizers(IF)and the organic manure-inorganic fertilizers(OMIF)on soil chemical properties,the composition of microbial communities.The study aimed to assess the effect of long-term fertilization on soil quality.The main results were listed as follows:1.The effects of different fertilization on the soil chemical properties are as follows.Increased N in fertilization treatments resulted in increased total N contents in the soil.The application of N fertilizers significantly increased the contents of soil OM and soil nitrate,which also increased with increases in the ratio of PMC in OMIF.No significant differences in ammonium nitrogen,pH,total P,available K,or available P contents were found among the treatments.In addition,the application of OMIF did not significantly increase both the total and available heavy metal contents.Compared to the background,the long-term nitrogen fertilizer reduced the pH of the soil.2.The effects of different fertilization on the fungal and bacterial community structure are as follows.Significantly lower fungal richness and higher bacterial richness were observed for the OMIF treatment compared to the other treatments.No obvious changes in fungal diversity were observed among the treatments,while decreased bacterial diversity was detected in the IF treatment.The compositions of the fungal and bacterial communities from soils treated with different fertilizer treatments(CK,IF3,OMIF3-3)were similar.There were no significant differences of dominated bacterial and fungal community structure on the phylum level in all treatment.3.Soil microbial community structure and soil chemical properties correlation analysis results showed that the change of soil microbial community structure is mainly related to soil total nitrogen,nitrate nitrogen and organic matter content,and a significant correlation with the nitrate nitrogen and the organic matter content was observed.The the fungal abundance-based coverage estimator(ACE)estimate showed a significant negative correlation with the soil OM/NO3-N content,while the correlation was positive for the bacterial ACE estimate.This study suggests that,the fungal and bacterial communities respond differently to the long-term organic-inorganic compound fertilization,which may results from different effects of OM/NO3--N contents on the composition of fungal and bacterial communities.