Project Details
Projekt
The unknown soil microbial biomass stoichiometry and its potential use – C:N:P:et al.
Subject Area
Soil Sciences
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 513567414
For fulfilling the diverse ecosystem functions in soil at high rates, which for instance are needed for soil fertility and health, a larger and more active soil microbial biomass (SMB) is advantageous. Commonly, SMB is determined by chloroform fumigation extraction of carbon (C), nitrogen (N), and phosphorus (P) and these three elements show a homeostatic stoichiometry. However, microorganisms consist of more elements, which play important roles in cell functioning, growth, and activities related to ecosystem services. But their stoichiometry in SMB is not known. According to the law of the minimum, growth or activity are limited by that nutrient which in relation to the amount needed has the lowest availability, though nowadays it has become clear that co-limitation of elements is the dominant case. However, some elements like manganese can substitute for others, e.g. magnesium, iron, and zinc. The ratio of C to the elements beyond N and P needed for growth and activity in soil is not known. Recently, we optimised a chloroform fumigation extraction method for analysis of other SMB elements. Using this new method the SMB of soil variants of two agricultural soils and according soil particle size fractions, i.e. sand, silt, and clay, will be analysed. While the first differ in nutritional status due to long-term fertilisation treatments, the latter differ due to diversity of minerals and in quality of associated soil organic matter. Furthermore, in incubation experiments elements will be added in several concentrations to soil. With these approaches the hypothesis will be tested that in contrast to C:N:P, elements which can be substituted for show a plastic stoichiometry. Measurements will include respiration and enzyme activity, while shotgun sequencing will enable analysis of element-related functional genes, e.g. those coding for metalloproteins. It will be tested whether the knowledge of stoichiometry of bioavailable elements and SMB elements can be used to enhance microbial growth and activity. The results obtained in this project will give insight into the stoichiometric phenotype of SMB beyond C, N, and P. This knowledge together with that of bioavailable elements in soil shall enable stakeholders to manipulate the soil microbial community by addition of specific elements in specific concentrations in order to enhance soil fertility and health and, thus, soil ecosystem services.
DFG Programme
Research Grants
Co-Investigator
Professor Dr. Florian Wichern
