Effects of green manuring on chemical characteristics and microecology of tobacco-growing soil in central henan.

OBJECTIVE

This study explored green manuring effects on microecology, carbon/nitrogen levels, and enzyme activity in tobacco-growing soils.

METHODS

After 30,000 kg·hm⁻² overpressure and 28 days of natural decomposition, plants (Hordeum vulgare L. (DM), Secale cereale L. (HM), Medicago sativa L. (MX), Vicia dasycarpa Ten. (SZ), Brassica napus L. (YC), and Astragalus sinicus L. (ZY)) were grown in a lab to analyze changes in carbon and nitrogen components, microbial community structure, and enzyme activities in the soil.

RESULTS

The results showed improved soil nutrition and increased organic matter, nitrate-nitrogen, and ammonium-nitrogen levels. Except for MX, the other treatments markedly enhanced carbon/nitrogen in the soil microbial biomass. Compared to the CK treatment, the HM treatment boosted alkaline phosphatase and catalase activities by 20.54% and 61.98%, respectively, and increased the soil microbial biomass carbon and nitrogen content by 99.59% and 61.07%, respectively. Green manuring altered bacterial and fungal community structures. Proteobacteria, Actinobacteria, Chloroflexi, Firmicutes, Acidobacteria, Planctomycotes, and Gemmatimonadetes were the dominant bacterial communities. MX significantly increased the abundance of Bacteroidetes. Over half of all soil fungi were Ascomycota, with SZ substantially increasing their abundance. LEfSe analysis revealed 29 differential bacterial and fungal species (LDA > 3.5); fungi comprised 29 distinct species in six treatments (LDA > 4), with the exception of the YC treatment. Fusarium and Mortierella were positively correlated with sucrase and urease activities and negatively correlated with other markers, whereas Sphingomonas was strongly negatively correlated with UE and positively correlated with other indicators. HM showed the highest relative abundance of genes related to the tricarboxylic acid cycle (icd), starch breakdown (malZ), nitrification process (amoABC, hao), and nitrogen fixation process (nifK, nifD, nifH). Secale cereale L. manuring effectively improved the carbon sequestration and nitrogen mineralization capacity of soil microorganisms.

CONCLUSION

Green manuring improved soil nutrition and microecology, controlling bacterial community composition, with optimal results when turning Secale cereale L. first.