Gaseous nitrogen losses from a subtropical sugarcane cropping system

Direct emissions of nitrous oxide (N2O) from farmed soils account for a large share of the climate forcing through food production. The FACCE ERA-GAS project “Mitigating Agricultural Greenhouse Gas Emissions by improved pH management of soils, MAGGE-pH” explores possibilities to reduce N2O emissions by liming soils beyond the minimum needed for crop growth.

Research ranges from N2O emission measurements in liming trials to manipulative laboratory studies and molecular assessments of functional microbial communities in long-term and more recently limed soils. The overarching goal is to understand how changing soil pH, a well-known and easy to control soil property, affects biotic and abiotic nitrogen transformations and their N2O yields. There is ample evidence that liming acidic soils improves bacterial N2O reduction to N2 in denitrification and coupled nitrification-denitrification, primarily due to enhanced maturation of the N2O reductase at high pH. On the other hand, liming appears to increases the N2O yield of nitrification by enhancing bacterial over archaeal ammonia oxidation.