Corn-soybean rotation and fertilization are common practices improving soil fertility and crop yield. Their effects on bacterial community have been extensively studied, yet, few comprehensive studies about the microbial activity, bacterial community and functional groups in a long-term continuous soybean cropping system after corn insertion and fertilization. The effects of corn insertions (Sm: no corn insertion, CS: 3 cycles of corn-soybean rotations and CCS: 2 cycles of corn-corn-soybean rotations) with two fertilization regimes (No fertilization and NPK) on bacterial community and microbial activity were investigated in a long-term field experiment. The bacterial communities among treatments were evaluated using high-throughput sequencing then bacterial functions were predicted based on the FaProTax database. Soil respiration and extracellular enzyme activities were used to assess soil microbial activity. Soil bacterial community structure was significantly altered by corn insertions (p < 0.01) and fertilization (p < 0.01), whereas bacterial functional structure was only affected by corn insertion (p < 0.01). The activities of four enzymes (invertase, β-glucosidase, β-xylosidase, and β-D-1,4-cellobiohydrolase) involved in soil C cycling were enhanced by NPK fertilizer, and were also enhanced by corn insertions except for the invertase and β-xylosidase under NPK fertilization. NPK fertilizer significantly improved soil microbial activity except for soil metabolic quotient (qCO₂) and the microbial quotient under corn insertions. Corn insertions also significantly improved soil microbial activity except for the ratio of soil induced respiration (SIR) to basal respiration (BR) under fertilization and the qCO₂ was decreased by corn insertions. These activity parameters were highly correlated with the soil functional capability of aromatic compound degradation, which was the main predictors of bacterial functional structure. In general, the combination of soil microbial activity, bacterial community and corresponding functional analysis provided comprehensive insights into compositional and functional adaptations to corn insertions and fertilization.

Rotation and fertilization are important methods used to improve crop yield. In particular, crop rotation is an effective means of enhancing ecosystem diversity; however, there exist relatively few studies regarding the effects of long-term maize–soybean rotation and fertilization on soil microbial communities. To further understand the changes in soil microbial community structure under long-term maize–soybean rotation and fertilization, we used a 9-year-old experimental site with maize–soybean rotation as the research object and soybean continuous cropping as a control. We explored the growth effects of soybean and the changes in soil microbial communities under the soybean–maize rotation system and fertilization treatments by analyzing the physicochemical properties of the soil, crop agronomic traits, yield, and changes in soil microbial community structure. The results show that, in comparison with soybean continuous cropping, the yield of soybeans was increased by 12.11% and 21.42% under maize–soybean rotation with different fertilization treatments, respectively. Additionally, there was a significant increase in the agronomic effects of nitrogen following rotation combined with fertilization. Moreover, the soil pH, SOM, and nutrient status were also improved. Bryobacter, Gemmatimonas, and Rhodanobacter were the dominant bacteria. Rotation treatment increased the relative abundance of Bryobacter and Rhodanobacter, and fertilization treatment increased the relative abundance of Gemmatimonas. Rotation also increased the stability of the bacterial community structure and strengthened the symbiotic relationship between species. The prediction of nitrogen-related functional genes indicates that rotation increased soil ammonification and nitrification. Heterocephalacria and Mrakia were the dominant fungal genera under crop rotation. The abundance of Saccharomyces Mrakia was significantly positively correlated with ammonium nitrogen levels and crop yield. Crop rotation increased the abundance of Saccharomyces Mrakia and reduced the abundance of Fusarium, but fertilization increased the abundance of Fusarium. Functional gene prediction also indicates that the relative abundance of plant pathogens was significantly reduced. This study provides a theoretical basis for soil microbial diversity and ecosystem service function in long-term soybean–maize rotation.

Saline soils are characterized by organic matter and nutrient deficiencies, and their mineral fraction consists almost exclusively of fine sand particles, resulting in an unstable soil formation process. Due to the high amount of soluble salts in the soil, the osmotic pressure of the soil is elevated, restricting water absorption. This ultimately leads to the death of the plant and adversely impacts crop growth and yield. Incorporating Fe²⁺ can improve fertilizer utilization efficiency by reducing the oxidation of NH₄⁺ to nitrogen (N₂). However, reports on the usage of iron addition for the improvement of saline-alkali soils are scanty. This study conducted an outdoor simulation in pots to assess the soils of soybean crops during the podding stage. The effects of Fe²⁺ along with organic fertilizer or bio-C addition were elucidated on the composition and function of saline and alkaline microbial communities. The findings were correlated with soil environmental factors to analyze the dynamic changes in soil microbial communities. The soil pH decreased by 1.22–2.18% and SOM increased by 2.87–11.77% with organic fertilizer (OF) treatment. Compared to the ck treatment (control without iron supplementation), other treatments showed an average increase in abundance of dominant phylum by 8.25–11.23%, and an increase in the diversity and richness of the microbial community by 1.73–10.87%. The harmful bacteria in the Actinobacteriota, Chloroflexi, and Basidiomycota groups reduced by 57.83%, 74.29%, and 67.29%, and the beneficial bacteria in Ascomycota increased by 18.23–20.39%. Fe²⁺ combined with organic fertilizer or bio-C treatment could weaken the competitive relationship between the various bacterial lineages, enhance synergistic ability, favor the function and structure of the microbial community, and thus, improve the soil environment. Overall, the application of Fe²⁺ combined with organic fertilizers improved the saline-alkali soil, while the biochar (C) treatment mainly affected the soil nutrients. Through its detailed analysis, the study provides actionable insights for farmers to manage soil fertility in saline-alkaline soils, thereby overcoming the challenges of poor yields due to salinity stress. This will lead to resilient and sustainable farming systems, contributing to global food security.

Aims: Soil nitrogen is recognized as a vital nutrient influencing soybean growth and yield. Hence, a comprehensive understanding of the intricate connections between shifts in nitrogen patterns and the behaviors of soil microbial communities and crucial enzymes in the nitrogen cycle is highly desirable. Methods: This study involved a rotation positioning experiment spanning 11 years (2012-2022). Measurement of soil microenvironment changes during the mature period for three consecutive years (2020-2022). Based on these groups, the study delved into the alterations in nitrogen patterns within the soybean rotation, examining both soil enzyme activity and microbial community dynamics. Results: Long-term crop rotation and nitrogen application led to an increase ranging from 2.16% to 108.34% in the nine components of soil nitrogen. Gemmatimonas , Rhodanobacter and Mrakia could effectively increase soil nitrogen content and had a reciprocal promotion with soil urease and protease activities, whereas Blastococcus and Fusarium increased soil nitrogen loss. Changes in inorganic nitrogen and total organic nitrogen resulting from crop rotation enhanced the abundance of soil microbial communities, reducing their diversity. Conclusions: Overall, findings demonstrate that long-term crop rotation and nitrogen management significantly influence soil nitrogen dynamics, microbial community structure, and enzyme activities. Thus, enhancing the functional capacities of soil microbial communities to support sustainable soybean production.

Plants photoreceptors perceive changes in light quality and intensity and thereby regulate plant vegetative growth and reproductive development. By screening a γ irradiation-induced mutant library of the soybean (Glycine max) cultivar “Dongsheng 7”, we identified Gmeny, a mutant with elongated nodes, yellowed leaves, decreased chlorophyll contents, altered photosynthetic performance, and early maturation. An analysis of bulked DNA and RNA data sampled from a population segregating for Gmeny, using the BVF-IGV pipeline established in our laboratory, identified a 10 bp deletion in the first exon of the candidate gene Glyma.02G304700. The causative mutation was verified by a variation analysis of over 500 genes in the candidate gene region and an association analysis, performed using two populations segregating for Gmeny. Glyma.02G304700 (GmHY2a) is a homolog of AtHY2a in Arabidopsis thaliana, which encodes a PΦB synthase involved in the biosynthesis of phytochrome. A transcriptome analysis of Gmeny using the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed changes in multiple functional pathways, including photosynthesis, gibberellic acid (GA) signaling, and flowering time, which may explain the observed mutant phenotypes. Further studies on the function of GmHY2a and its homologs will help us to understand its profound regulatory effects on photosynthesis, photomorphogenesis, and flowering time.