Effects of different tillage practices with organic fertilizers on rhizosphere soil microbial communities of maize in saline-alkali soils

The aim of this study is to investigate the effects of different tillage practices with organic fertilizers on the chemical properties and microbial community structure of maize rhizosphere soil in saline-alkaline soil, in order to identify the most suitable combination of tillage practices and organic fertilizer application, so as to provide an important basis for improving saline-alkaline soil and understanding the microbial community characteristics of maize rhizosphere soil. In this study, a split-zone experimental design was adopted, with two tillage practices in the main zone: CT (conventional tillage) and DV (vertical deep rotary tillage), and four levels of organic fertilizer application in the secondary zones: O1 (0 kg∙hm^-2), O2 (7 500 kg∙hm^-2), O3 (15 000 kg∙hm^-2), and O4 (22 500 kg∙hm^-2), in order to investigate the effects of different tillage practices combined with organic fertilizer on the rhizosphere of maize in saline-alkaline soils. organic fertilizers on rhizosphere soil soil chemical properties and microbial community structure of maize in saline soil. The results showed that under DVO3 and DVO4 treatments, the pH and total salt content of maize rhizosphere soils were significantly reduced by 3.94%-9.20% and 6.31%-25.96% compared with the other treatments, The contents of organic matter, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium significantly increased by 5.29%-45.24%, 4.71%-24.34%, 13.63%-32.67%, and 10.77%-34.25%, respectively, compared to other treatments, and the differences between DVO3 and DVO4 treatments were not significant. Compared to the other treatments, the richness and diversity of the microbial community in the maize rhizosphere soil were significantly enhanced under the DVO3 and DVO4 treatments, and the differences between the DVO3 and DVO4 treatments were not significant. In addition, DVO3 and DVO4 treatments significantly increased the relative abundance of Proteobacteria and Bacteroidetes in the bacterial dominant phylum and of Ascomycota and Basidiomycota in the fungal dominant phylum, as well as the relative abundance of Ohtaekwangia, Gp6, and Gp7 in the bacterial dominant genus and of Ascobolus, Filobasidium, and Botryotrichum in the fungal dominant genus, and the differences between the DVO3 and DVO4 treatments were not significant. The relative abundance of the above phylum and genus was positively correlated with the organic matter and fast-acting nutrient content of maize rhizosphere soil. In summary, vertical deep rotary tillage with 15 000-22 500 kg∙hm^-2 organic fertilizers can significantly reduce the pH and total salt content of saline soils, increase the content of quick-acting nutrients and organic matter, and improve microbial abundance and diversity, which is conducive to soil improvement and nutrient cycling in saline soils.