Molecular Soil Biology 2025, Vol.16, No.5, 272-286 http://bioscipublisher.com/index.php/msb 279 33.6%, while in the alkaline sand ginger black soil, nitrogen accumulation was reduced by 21.7%. The reason for the analysis may be related to the different competitiveness of the original symbiotic nitrogen-fixing bacterial communities in different soils and the opposite direction of the soil nitrogen cycle process affected by inoculation. When promoting microbial agents, the strain type should be selected according to the soil: when the abundance of inherent soil bacteria is high, strains with strong competitiveness should be selected; salt-alkali-tolerant strains should be selected for saline-alkali soil; acid-tolerant rhizobia should be selected for acidic soil. In addition, the "microbial community package" of combined inoculation of multiple functional microbial agents has gradually gained attention. For example, mixed inoculation of rhizobia with growth-promoting bacteria (PGPR) can synergistically promote the development of legume roots and nitrogen fixation efficiency. Studies have reported that co-inoculation of rhizobia and Pseudomonas on peas can significantly alleviate continuous cropping obstacles and increase plant dry weight and photosynthetic performance. For example, some Bacillus preparations can produce plant hormones, and co-inoculation with rhizobia can increase the number and yield of soybean nodules (Miljaković et al., 2022). The effectiveness of microbial preparations varies in different soils, but reasonable selection and application can significantly exert their yield-increasing potential and is an important auxiliary means for the green and efficient cultivation of legume crops. 5.3 Application examples of formula fertilizers and controlled-release fertilizers in different soils The application of new fertilizers provides a technical approach for efficient management of legume nutrients under different soil conditions. Among them, formula fertilizers are customized according to the fertilizer requirements of crops and the characteristics of soil fertilizer supply. They generally contain a variety of macro- and micro-nutrients, which can meet the needs of legumes during the growth period at one time. The use of special formula fertilizers for legumes on alkaline soils lacking trace elements can effectively prevent nutrient deficiency and increase the pod setting rate and seed fullness. In recent years, special fertilizers for peanuts and soybeans developed in different regions have been promoted in production. For example, the application of special soybean fertilizers containing gypsum and boron and zinc on alkaline soils in North China has a significantly better yield-increasing effect than conventional NPK compound fertilizers. For example, the peanut fertilizer promoted on red soils in the southwest has increased the phosphorus and calcium content, which significantly promotes pod development. Controlled-release fertilizers slowly release nutrients through special coatings or slow-release technologies, which are also suitable for medium-fertilization crops such as legumes. Studies have shown that the application of controlled-release urea on soybeans can simultaneously increase yield and nitrogen utilization without weakening biological nitrogen fixation (Clovis et al., 2023). In a field trial, the application of controlled-release urea did not significantly differ from conventional urea in soybean nodulation number and nitrogenase activity, but increased grain yield by more than 6%. This is because controlled-release fertilizers slowly release nitrogen, avoiding the inhibition of nodule symbiosis by excess nitrogen in the seedling stage (Abulfaraj and Jalal, 2021). Controlled-release phosphate fertilizers also have potential in leguminous crops, slowing down the fixation of phosphorus in the soil and increasing the supply of effective phosphorus in the later stage. It is worth noting that new fertilizers are often more expensive and should be used in a targeted manner according to soil conditions to obtain the best input-output ratio. For example, the use of controlled-release fertilizers on sandy soils that are prone to leaching is more effective, while clay soils have a relatively weak response to the yield increase of controlled-release technology due to their strong buffering capacity (Ren et al., 2022). For example, the yield increase of formula fertilizers on nutrient-rich black soil is limited, but the effect is significant on barren red soil. Therefore, these new fertilizer technologies should be applied first to the soil types that need them most. A combination of various measures, such as the combined application of controlled-release nitrogen fertilizers, phosphorus bacteria agents and formula fertilizers, is expected to achieve a win-win situation of efficient nutrient management and high bean yields on difficult soils. With the development of fertilizer technology, new products that more accurately match soil nutrient supply and demand will continue to emerge, pushing the fertilization of bean crops from "balanced fertilization" to "intelligent fertilization."
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