Combined application of amendments enhances maize yield by improving soil properties, bacterial communities and increasing bacterial abundance in saline-alkali soil

Soil salinization poses a severe threat to crop survival and productivity. Application of amendments are considered as effective strategies for improving soil properties, bacterial communities and crop yield. Thus, a field study was conducted to examine the impacts of amendments on soil properties, bacterial communities, and maize yield. High-throughput absolute quantification sequencing was used to investigate soil bacterial communities during two growing seasons. Five treatments including: (i) control without amendments (CK); (ii) desulfurization gypsum (DE); (iii) soil ameliorant (SA); (iv) farm manure (FA); (v) DE plus SA plus FA (DSF). The results showed that amendments application led to increased soil nutrient levels and decreased soil pH and EC. Enzyme activities were significantly enhanced in the FA and DSF treatments, while no significant differences observed among DE, SA and CK treatments. Five predominant phylum were detected including Proteobacteria, Acidobacteria, Gemmatimonadetes, Bacteroidetes and Actinobacteria in all soil samples. The application of amendments increased bacterial diversity, richness, and functional potential of the N and C cycling, and altered the soil bacterial community structure relative to the CK treatment, in which DSF treatment had the greatest effect. The interconnectivity of the bacterial co-occurrence network was notably strengthened after applying amendments, with Proteobacteria identified as the key taxa among the treatments. Maize yield improved after the application of amendments, and the structural equation modeling (SEM) results indicated that soil properties, enzyme and bacterial community were the major factors influencing yield performance. Therefore, our study provides valuable insights into the application of different amendments in improving soil properties, bacterial communities and sustaining agricultural output in saline-alkali soils of Hetao Plain.