Nitrogen (N), while the most abundant element in the atmosphere, is an essential soil nutrient that limits plant growth. Leguminous plants naturally possess the ability to fix atmospheric nitrogen through symbiotic relationships with rhizobia in their root nodules. However, the widespread use of synthetic N fertilizers in modern agriculture has led to N enrichment in soils, causing complex and profound effects on legumes. Amid ongoing debates about how leguminous plants respond to N enrichment, the present study compiles 2174 data points from 162 peer-reviewed articles to analyze the impacts and underlying mechanisms of N enrichment on legumes. The findings reveal that N enrichment significantly increases total legume biomass by 30.9% and N content in plant tissues by 13.2% globally. However, N enrichment also leads to notable reductions, including a 5.8% decrease in root-to-shoot ratio, a 21.2% decline in nodule number, a 29.3% reduction in nodule weight, and a 27.1% decrease in the percentage of plant N derived from N₂ fixation (%Ndfa). Legume growth traits and N₂-fixing capability in response to N enrichment are primarily regulated by climatic factors, such as mean annual temperature (MAT) and mean annual precipitation (MAP), as well as the aridity index (AI) and N fertilizer application rates. Correlation analyses show that plant biomass is positively correlated with MAT, and tissue N content also exhibits a positive correlation with MAT. In contrast, nodule numbers and tissue N content are negatively correlated with N fertilizer application rates, whereas %Ndfa shows a positive correlation with AI and MAP. Under low N addition, the increase in total biomass in response to N enrichment is twice as large as that observed under high N addition. Furthermore, regions at lower elevations with abundant hydrothermal resources are especially favorable for total biomass accumulation, indicating that the responses of legumes to N enrichment are habitat-specific. These results provide scientific evidence for the mechanisms underlying legume responses to N enrichment and offer valuable insights and theoretical references for the conservation and management of legumes in the context of global climate change.

Organic agriculture is widely regarded as an important approach to reducing biodiversity loss and promoting sustainable agricultural development compared to conventional agriculture. Notably, organic farming practices have substantially boosted the diversity of soil microbial communities. However, empirical studies on the functional structure of soil microbial communities in organic agroecosystems and the mechanisms influencing them remain relatively scarce. Using high-throughput sequencing technology, we analyzed soil microbial communities associated with organic (orange lands) and conventional (coffee and maize lands) farming practices in the Gaoligong Mountains (GLGM) region, with the aim of revealing differences in soil properties, microbial community structure, and functional composition across different agricultural management practices. The results revealed that organic farming boosted soil organic carbon and fertility, driving changes in the microbial community composition. Organic farming notably increased the abundance of bacterial functional groups involved in the carbon and nitrogen cycles but decreased the abundance of symbiotic fungi. Furthermore, no significant differences were observed in the abundance of saprotrophic and pathogenic fungi between the organic and conventional farming systems. The present study demonstrates that organic farming enhances the functional roles of oil microorganisms in nutrient cycling and overall ecosystem processes by enhancing soil’s organic carbon content and soil fertility, thereby modifying the soil’s microbial community structure and functions. Overall, organic farming contributes to improvements in soil health and supports the sustainable development of agriculture in the GLGM region.

Fusarium oxysporum and Fusarium solani are the main soybean root rot pathogens in northern China. We investigated the distribution and driving factors of Fusarium under different cropping systems to evaluate and regulate soil health. The factors affecting Fusarium in soybean cropping systems were assessed using high-throughput sequencing of ITS1 to identify soil microbial population diversity, and then the soil physicochemical properties were assessed to determine the levels of various elements present in the environment. According to the results, the abundance of Fusarium was obviously reduced in the corn-soybean rotation and uncultivated soil systems. The relative abundance of Fusarium in the soil and the abundance and diversity of fungal communities were significantly positively associated with the abundance of Ascomycota. Additionally, the relative abundance of Fusarium was significantly positively correlated with the zinc (Zn) content. When the Zn content was high, the abundance of Fusarium increased, and the correlations with Chaetomium, Cryptococcus, Penicillium and Trichoderma significantly decreased. Soybean yield was significantly negatively correlated with fungal community abundance and diversity. Based on our results, the uncultivated soil and corn-soybean rotation cropping systems improved the organizational structure of the soil fungal community and were conducive to the health and production of soybean.

Soil fungi are closely tied to their surrounding environment. While numerous studies have reported the effects of land-use practices or elevations on soil fungi, our understanding of how their community structure and diversity vary with elevation across different land-use practices remains limited. In the present study, by collecting soil samples from four different land uses in the Gaoligong Mountain area, namely shrublands (SLs), coffee plantations (CPs), cornfields (CFs), and citrus orchards (COs), and combining them with the changes in altitude gradients (low: 900 m, medium: 1200 m, high: 1500 m), high-throughput sequencing technology was used to analyze the composition and diversity of soil fungal communities based on the collected soil samples. The results showed that the interaction between land-use types and elevation significantly influenced the structure and diversity of fungal communities, although their relative importance in shaping fungal diversity or community structure varied. Specifically, elevation posed a stronger effect on fungal community alpha-diversity and functional guilds, whereas land-use types had a greater influence over fungal community composition. Our study reveals the individual and combined effects of land-use practices and elevation on the structure and diversity of soil fungal communities in the Gaoligong Mountain region, enhancing our understanding of the distribution patterns and driving mechanisms of soil fungal communities in this biodiversity-rich region.