Parent material and land-use intensity as driver for niche complementarity in phosphorus mobilisation between plants and microbes
Phosphorus is an essential macronutrient that plays a central role in the cellular processes of plants and microorganisms. However, in soils, phosphorus availability is limited by the pH-dependent solubility of phosphorus-containing minerals and sorption onto charged surfaces. Its additional input is influenced by land use intensity. Consequently, plants and microorganisms must develop alternative and competitive strategies for phosphorus mobilisation, such as recycling from organically bond P and acquisition from P-containing minerals. These strategies are particularly important in grassland ecosystems, where much of the phosphorus is supplied in organic form and subsequently removed through mowing and grazing. Finally, a detailed mechanistic understanding of the interactions between plants, microorganisms and soil in phosphorus mobilisation is missing.
The project “P-Niche” focuses on the mobilisation of phosphorus by microorganisms and plants in grassland ecosystems and investigates how this interaction is influenced by land use intensity and soil properties. The aim is to develop a mechanistic understanding of the dynamics and driving factors of phosphorus mobilisation in a soil-plant-microbe continuum. Key microbial taxa will be identified, and their functional redundancy will be studied in plant rhizospheres and bulk soil. Additionally, the extent to which the soil microbiome’s functional potential is translated into active phosphorus mobilisation will be examined.
H1: There is a gradient from P acquisition to P recycling strategies from high to low LUI being more pronounced in regions with low inherent P contents.
H2: Extensification fosters P recycling strategies as well as microbiota with more versatile P mobilisation strategies.
H3: Plants rely more on P acquisition while soil microorganisms increase P recycling strategies in case of land-use extensification especially at sites with generally low P stocks. At sites with high P stocks additive effects of plants and soil microorganisms can be observed alternatively.
H4: During winter, P accumulates in microbial biomass, but less so under low LUI because of the microbial use of alternative storage compounds that do not contain P.
The project combines field studies, molecular analyses and controlled laboratory experiments. We will rely on the experimental grassland plots and on the plots of the LUX experiment where fertilization ceased. Short and longread metagenomic approaches will be used to characterise microbial communities and their functions in the rhizosphere of Lolium perenne and in bulk soil collected in the field across seasons (spring, summer, autumn, winter). This will be complemented by measurements of inorganic and organic phosphorus fractions, phosphorus in microbial biomass as well as enzyme activities in soil. Finally, we will set up mesocosm experiments containing soil from the field and L. perenne and apply isotope tracers (³³P in apatite, ¹³C in litter) to follow the mobilisation of phosphorus from inorganic and organic sources by plants and soil microorganisms. This will be complemented by metatranscriptomic analyses of the plant and microbiome, respectively.
Scientific assistants
