Characteristics And Mechanism Of Inorganic Phosphorus Fractionation In Soils From Mongolian Plateau

Phosphorus is an essential nutrient element for plants to carry out various life activities.Its geochemical morphology and content distribution are important parameters affecting the growth and development of animals,plants and microorganisms in the ecosystem,and are of great significance to the dynamic changes and stabilization of soil carbon pools in Mongolian plateau.Representative surface and sectional soil samples were obtained from the Mongolian Plateau to analysis the fractional characteristics and spatial distribution patterns of phosphorus fractionation in different grassland types of soils,based on the continuous extraction method of phosphorus fractionation.By coupling the topography,climate,soil physical and chemical properties,and land use patterns in the study area,the correlations mechanism between soil phosphorus fractionation and its corresponding factors were explored,which revealed the morphology-based relationship between soil phosphorus and TOC on the Mongolian plateau and its influence mechanism.This study gives a comprehensive insight of the role of soil phosphorus in the Mongolian plateau grassland ecosystem,which could provide a theoretical basis for a more accurate understanding of the ecological significance of different fractionations of phosphorus in the Mongolian plateau grassland ecosystem and a more rational conservation and restoration measure for the Mongolian plateau grassland ecosystem.The main results are as follows:1.The orders of soil phosphorus in the Mongolia Plateau are as follows:meadow steppe>typical steppe>desert steppe,with its fractionation orders are:Ca₁₀-P>O-P>Ca₈-P>Fe-P>Ca₂-P>Al-P.On the soil profile,the percentage of inorganic phosphorus and available phosphorus showed significantly elevated and decreasing trends,respectively.2.The differential fractionation distribution of soil inorganic phosphorus was closely related to factors such as topography and climatic conditions.The higher altitude corresponding to the higher soil TIP and available phosphorus content.Moisture and temperature and their determined dryness both have latitudinal zonation patterns,also TIP and available phosphorus and dryness also show latitudinal zonation trends.3.Soil minerals and iron and aluminum oxides in the study area are closely related to available phosphorus fractionation,implying the potential bioavailability of mineral-bound phosphorus.4.The differences in soil phosphorus distribution were indirectly caused by the selected grazing practices in the study area.By affecting soil p H,TOC and TN contents,biomass and biodiversity index,seasonal grazing resulted in higher inorganic phosphorus and TIP and TP contents than those of sedentary grazing areas.5.The relationship between the morphology-based soil phosphorus and TOC showed that,in addition to hydrothermal conditions,the vegetation biomass and its diversity in the study area depend on the effective phosphorus sources of the soil rather than TP,TIP and potential phosphorus sources(Ca₁₀-P,O-P)with poor availability.6.Inferred from morphological analysis,to explore the recycling of materials,energy flow and sustainable development of grassland ecosystems may result in increased uncertainty in the relevant conclusions via traditional total nutrients such as TP,TN and TOC.Environmental geochemical ideas and methods such as nutrient morphology and effectiveness can deepen the understanding of ecologically relevant mechanisms and facilitate a more accurate portrayal of the coupled biogeochemical cycling mechanisms of elements in ecosystems.