Using soil health parameters as indicators of sustainable management of dry lands in Northern Ethiopia
Abstract
Land use change and agricultural intensification in developing countries affect terrestrial carbon (C) stocks, CO2 efflux, microbial communities and overall soil health. However, the response of soil health to diverse expressions of global change especially in dry lands remains unclear. We therefore assessed the effects of four land use types typical for arid northern Ethiopia (forests, exclosures, grazing lands and intensively cultivated croplands) on microbial biomass carbon (MBC), water extractable organic carbon (WOC), metabolic quotient (qCO2), substrate use efficiency (SUE) and dynamics of 14C labelled as soil health indicators. Irrespective of the land use, MBC but not SUE decreased 2 to 8-fold with increasing depth demonstrating the C limitation of subsoil microbial communities under all land use forms. Sandy texture, which permits seepage and leaching of WOC into lower layers and promotes subsoil microbial communities adapted to frequent input of easily accessible C substrates. However, significantly higher qCO2 were recorded in subsoils compared to topsoils especially in croplands with low MBC. High glucose-14C incorporation (≈ 20%) into their low microbial biomass indicates a high SUE in croplands and reflects a better nutrient supply of these microbial communities. Mineralization of up to 95% of 14C labeled glucose in top soils of forest and grazing lands was higher than croplands and even exclosures. This demonstrates that 6 - 10 years of exclosure establishment does not result in soil microbial communities and a soil C dynamics resembling those of natural forests. Our study demonstrates that land use change can negatively affect the ecological performance of microbial communities and that these impacts are more severe in sandy than in clayey soils. Mitigation strategies such as minimum tillage or residue retention in cultivated croplands can increase microbial abundance and activity and thus ensure environmental sustainability and mitigation of climate change effects in dry lands.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B21F2406O
- Keywords:
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- 0402 Agricultural systems;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCES;
- 0486 Soils/pedology;
- BIOGEOSCIENCES