In order to gure out the effect of organic fertilizers with different carbon-nitrogen (C/N) ratios on the soil improvement and the healthy cultivation, the pot experiment method was used to study effects on the physical and chemical properties and the bacterial community structure of sandy loam soil using ve treatments of chemical fertilizer application with the C/N ratios of 15 (CN15), 20 (CN20), 25 (CN25), 30 (CN30) and the control (CK) respectively. Results show that the organic materials with different C/N ratios signi cantly improve the soil porosity and water content, which all show a linear change rule with the C/N ratio. It can also signi cantly increase the soil total carbon, total nitrogen, soil C/N ratio, soil microbial biomass carbon, microbial biomass nitrogen and microbial biomass C/N ratio. Among them, CN30 signi cantly increases the soil total carbon and C/N ratio, which are 5.34%-24.13% and 8.87%-30.15% respectively compared with other treatments. It can be also found that the dominant ora (at the phylum level) of each treatment are Actinobacteria, Proteobacteria and Chlorobi. The CN30 treatment presents the most obvious improvement in the diversity and richness of the soil bacterial community and is more conducive to the growth and reproduction of Proteobacteria and Firmicutes. The correlation analysis shows that C total /N total and C mic /N mic are the most important environmental factors affecting the soil physical and chemical properties and their correlation with the bacterial communities. The higher C/N ratio of organic materials results in a more signi cant improvement of the soil physical and chemical properties. This study provides a new theoretical basis for the soil health cultivation technology.

In order to explore the impact of biochar and green manure on the micro-ecological environment of citrus soil, a field experiment was used to set CK (conventional fertilization), T1 (5.0 kg/biochar) and T2 (5.0 kg/biochar + 10% nitrogen fertilizer reduction + green manure), for measuring the 3 kinds of fertilization affectness to the fungal diversity and community structure of citrus rhizosphere soil. The results showed that, compared with CK, the pH, alkali-hydrolyzable nitrogen, available phosphorus and available potassium content of T1 and T2 treatments were significantly increased, and soil bulk density was significantly reduced. Application of only biochar increased the diversity of soil fungi, but reduced the richness of fungi. Combined application of biochar and green manure significantly increased the diversity and richness of fungi. Application of biochar increased the relative abundance of Basidiomycota, Schizoplasmodiida, and Talaromyces in soil, and decreased relative abundance of Ascomycota, Mucoromycota, Chaetomium and Fusarium. The study shows that the combined application of biochar and green manure can significantly increase the soil fungal diversity, reconstruct community structure of soil fungi, reduce the abundance of pathogenic bacteria, and promote micro-ecological balance in soil for citrus and soil health。

In order to figure out the effect of organic fertilizers with different carbon-nitrogen (C/N) ratios on the soil improvement and the healthy cultivation, the pot experiment method was used to study effects on the physical and chemical properties and the bacterial community structure of sandy loam soil using five treatments of chemical fertilizer application with the C/N ratios of 15 (CN15), 20 (CN20), 25 (CN25), 30 (CN30) and the control (CK) respectively. Results show that the organic materials with different C/N ratios significantly improve the soil porosity and water content, which all show a linear change rule with the C/N ratio. It can also significantly increase the soil total carbon, total nitrogen, soil C/N ratio, soil microbial biomass carbon, microbial biomass nitrogen and microbial biomass C/N ratio. Among them, CN30 significantly increases the soil total carbon and C/N ratio, which are 5.34%-24.13% and 8.87%-30.15% respectively compared with other treatments. It can be also found that the dominant flora (at the phylum level) of each treatment are Actinobacteria, Proteobacteria and Chlorobi. The CN30 treatment presents the most obvious improvement in the diversity and richness of the soil bacterial community and is more conducive to the growth and reproduction of Proteobacteria and Firmicutes. The correlation analysis shows that Ctotal/Ntotal and Cmic/Nmic are the most important environmental factors affecting the soil physical and chemical properties and their correlation with the bacterial communities. The higher C/N ratio of organic materials results in a more significant improvement of the soil physical and chemical properties. This study provides a new theoretical basis for the soil health cultivation technology.