Project Details
Projekt
Train SpaTEn: Transport enhances the energy return on investment in the spatially and temporally heterogeneous soil environment
Subject Area
Soil Sciences
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 465127287
In soils, the partitioning of carbon (C) from a given substrate between catabolism and anabolism (referred to as substrate-use efficiency, SUE) is affected by the functional complexity of the given substrate and the soil environment. As “passive waiting” is the most common nutrient and substrate acquisition strategy for soil prokaryotes, the likelihood of contact between a given substrate and its decomposers is rather a function of short-distance transport of the substrate than of microbial mobility and active movement. The patchy and temporally irregular substrate supply in soils leads to two end-member scenarios causing reduced microbial use of a given substrate: (i) hot spots with high substrate concentrations where the microbial growth-concentration relationship is saturated, resulting in reduced microbial activity and (ii) cold spots where substrate concentrations in the soil solution are too small and irregular and the metabolic investment is too high to warrant substrate utilization energetically. Transport processes will provide an effective contribution to the termination of hotpots by balancing substrate gradients between hot and cold spots. However, despite decades of research on flow processes in soil, there is still a need to link flow paths and the resultant heterogeneous moisture distributions to soil microbial functioning. The scientific approach of the proposed project is based on unraveling the interactions between spatial and temporal heterogeneity in substrate and nutrient availability, and how their modulation by transport processes shapes microbial catabolism and anabolism in soil. This will be achieved by (i) studying how transport of substrate or Nitrogen (N) improves SUE either due to the extending spatial distribution of the substrate to soil compartments where there is still sufficiently N available, or due to N transport into substrate rich compartments where the nutrient is lacking; (ii) analyzing how the boundary conditions pore size distribution and sorption-active minerals alter the effect of transport processes on microbial energy and C use; (iii) unraveling to which extend the hypothesized positive impact of N transport to substrate rich compartments on SUE is reduced by the need of the microbial community to partition Nitrate under oxygen deficiency to denitrification and anabolism; and (iv) determining how preferential flow after drought and re-wetting steers timely water availability for the microbial community and thus the lag-phase of microbial reactivation and coinciding C flow through catabolic and anabolic pathways.
DFG Programme
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