Abstract: Aim Phosphorus(P) is one of the important nutrient elements to maintain plant growth and the integrity of terrestrial ecosystem, and is the limiting nutrient element second only to nitrogen in global arid ecosystems. The storage and supply capacity of phosphorus is extremely important for the healthy growth of plants, the survival of microorganisms and the stability of the soil ecosystem. Given the scarcity of phosphorus in terrestrial ecosystems and the fact that the form of inorganic phosphorus can determine the availability of soil phosphorus, studying the effects of different grassland utilization patterns on soil inorganic phosphorus components under changes in precipitation intervals is of great significance for promoting the sustainable development of grassland ecosystems. Methods This study employed a combination of field in-situ experiments and laboratory analyses to compare the effects of three grassland utilization methods (grazing, cutting, and enclosure) on soil Pi fractions in temperate meadow steppe under different precipitation intervals. Important findings The results showed that precipitation intervals and grassland utilization methods directly altered soil Pi content (r = 0.38, p < 0.01) and indirectly influenced Pi fractions through modifying soil organic carbon (SOC) (r = 0.21). SOC exhibited significant positive correlations with total phosphorus (TP) (r = 0.51, p < 0.01), which in turn positively regulated Pi fractions (r = 0.61, p < 0.001), particularly Al-P and Fe-P (p < 0.05). Additionally, SOC strongly influenced microbial biomass C, N, and P (r = 0.69, p < 0.001), which moderately regulated Pi fractions (r = 0.04). Dominant bacterial phyla (Actinomycetota, Pseudomonadota, Acidobacteriota, and Planctomycetota, collectively >70%) significantly correlated with SOC and microbial biomass nitrogen (MBN) (p < 0.05) in regulating Pi fractions. Planctomycetota further showed significant positive correlations with microbial biomass carbon (p < 0.01) and Fe-P content (p < 0.05). Ascomycota dominated fungal communities across treatments, exhibiting direct positive effects on Ca-P (p < 0.01). Chytridiomycota and Basidiomycota influenced Pi fractions through contrasting effects on available phosphorus (AP), with O-P showing significant positive correlation with AP content.

Key words: Temperate meadow steppe, Grassland utilization methods, Precipitation intervals, Soil inorganic phosphorus fractions