The use of chemical fertilizer along with organic fertilizer is an important agricultural practice that improves crop yield but also affects soil biogeochemical cycles. In this study, a maize field experiment was conducted to investigate the effects of NPK fertilizer (NPK), organic fertilizer (OF), and their combination (NPK+OF) on soil chemical properties, bacterial and fungal community structures, and diversity compared the control (CK, without any fertilizer). The results showed that the application of OF and NPK-combined OF increased soil organic matter (OM), total N, total P, available N, available P, and available K levels. For alpha diversity analyses, the application of fertilizers led to decreases in soil bacterial and fungal Shannon indices (except for NPK in fungi). Compared with CK, NPK, OF, and NPK+OF fertilization treatments significantly increased the abundances of Acidobacteriota, Gemmatimonadota, and Basidiomycota. Network analysis showed that fertilization produced fewer connections among microbial taxa, especially in the combination of NPK and OF. A redundancy analysis combined with Mantel test further found that the soil OM, available N and P were the main soil-fertility factors driving microbial community variations. Therefore, using organic fertilizer or biological fertilizer combined with chemical fertilizer to improve the status of soil C, N, and P is a promising method to maintain the balance of soil microorganisms in maize field.

Salinity is one of the most devastating abiotic stresses limiting crop productivity. Here, the salinity tolerance level and physiological changes in Echinochloa frumentacea in saline and alkaline soils were estimated by studying root morphology, quantifying ions (Ca2+, K+, Na+, Ca2+/Na+, and K+/Na+) in roots, and measuring antioxidant enzyme activities, malondialdehyde (MDA), proline, and soluble sugar contents. Echinochloa frumentacea was tested against four neutral and alkaline salts, NaCl: Na2SO4:NaHCO3:Na2CO3 in different proportions at 60, 120, 180, 240, and 300 mmol L−1 concentrations. Echinochloa frumentacea was evaluated and compared with plant species, which are commonly cultivated in non-saline and alkaline soils i.e. Echinochola crusgalli, Avena sativa, Salicornia europaea, Medicago sativa, and Glycyrrhiza uralensis. The results revealed an increase in root length, diameter, absorption area, fresh, and dry weight at 120 mmol L−1. However, a gradual decrease in these parameters was observed at higher salt concentrations. In contrast, an increase in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities, and MDA and proline levels were observed with increasing salt concentration. The roots of E. frumentacea absorbed higher levels of ions than the other five forage plant species. Higher K+/Na+ and strong root structure in E. frumentacea indicate its better tolerance in saline soil than in alkaline soil. Our results demonstrate that E. frumentacea can tolerate up to 120 mmol L−1 salt in a saline–alkaline environment and is more suitable for growth in saline soil. In addition, the root system of E. frumentacea can be used to dechlorinate the chloride from soil and reduce its toxic effect on plants. It can also be used as a target species for selection and breeding programs to improve salt tolerance in future studies.