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Dr. Nele Meyer

2nd prize of the year 2018 (awarded twice)

„Sensitivity of soil organic matter turnover to temperature and nutrient supply“

Institute of Crop Science and Resource Conservation at University Bonn

© Geoverbund ABC/J / Forschungszentrum Jülich GmbHDr. Nele Meyer
Copyright: Geoverbund ABC/J / Forschungszentrum Jülich GmbH

Soil organic carbon (SOC) turnover plays an important role in the earth’s carbon (C) cycle but is increasingly affected by global change, which includes, amongst others, rising temperatures, increasing nitrogen (N) deposition, and altered phosphorus (P) supply. The degree and direction by which SOC turnover responds to changing temperature and nutrient supply, however, are still a matter of debate. The overall aim of this work was to identify the spatial variability in the response of SOC turnover to changes in temperature and nutrient supply and to derive the regulating factors.

The effect of temperature was studied on a regional scale (Rur catchment, Germany/Belgium/Netherlands) by incubating samples from 108 soils at five temperatures from 5-25°C and measuring CO2 release using a Respicond system. The effect of nutrient supply on soil respiration was investigated in soils with pronounced spatial, temporal, and vertical gradients of nutrient availability (long-term bare fallow soils and tropical soils) by adding glucose with and without additional N and P supply and measuring the induced soil respiration.

The results indicate that the response of SOC turnover to temperature and altered nutrient supply is spatially variable but largely predictable by environmental soil classes (i.e., a combination of land use, soil group, and texture) and by the soil’s initial nutrient conditions. The identification of spatial patterns and their regulating factors provides a first basis to systematize the observed variability across the landscape towards their representation in carbon- and earth system models.