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SPP 1090 AG 3: The function of soil microorganisms during mineralisation and stabilisation of organic substances in microhabitats
Project
Project code: DFG SPP 1090
Contract period: 01.01.2000
- 01.01.2006
Purpose of research: Basic research
Spatial soil ecology is the key to understand the function of soil biodiversity for organic matter cycling. Therefore, in the first part of the project we investigated the influence of organic matter amendment on microbiological properties (organic matter content, enzyme activities, total microbial biomass and microbial population structure) of particle-size fractions. We compared two treatments: no fertilization (control) and 12 t FYM ha-1 year-1 (farmyard manure). Since 1878, the fine fractions contained most C and N, microbial biomass, total amount of phospholipid fatty acids (PLFAs) and highest invertase activity. Xylanase activity as well as fungal biomass increased only gradually with diminishing particle size, whereas the relative abundance of fungi decreased with diminishing particle size. The least diversity of the soil microbial community - indicated by the smallest Shannon index based on the abundance and amount of different PLFAs and low number of terminal restriction fragments (T-RFs) of 16S rRNA genes - was found in the sand fractions. The results supported the hypothesis that this microhabitat is colonized by a less complex bacterial community than the silt and clay fractions (Poll et al. 2003). In the second part of the project our aim is to understand the function of microorganisms for the mineralization of organic matter at the soil-litter interface. Microcosms using different water content and presence or absence of irrigation simulate different transport mechanisms (diffusion, convection) of low molecular weight substrates and their impact on soil microorganisms. Microcosms experiments are performed in a climate chamber to achieve constant incubation conditions. At different distances from the soil-litter interface (0.0-0.4, 0.4-0.8, 0.8-1.2, 1.2-1.6, 1.6-2.0, 2.0-3.0, 3.0-4.0, 4.0-5.0, 5.0-7.0, 7.0-10.0 µm), we will measure enzyme activities and microbial biomass as well as C12/13-ratios of the soil organic matter and PLFAs.
Section overview
Subjects
- Soil science
