How well can we assess impacts of agricultural land management changes on the total greenhouse gas balance (CO2, CH4 and N2O) of tropical rice-cropping systems with a biogeochemical model?

Abstract

Paddy rice is the main cropping system in Southeast Asia. However, water scarcity arising from competition from other sectors, rainfall variability and climate change increasingly challenges global rice production. One option to adapt to lower water availability is switching from paddy rice to less irrigation intensive upland cropping systems. Such land management change (LMC) is likely to significantly affect ecosystem carbon and nitrogen cycling and its greenhouse gas (GHG) balance. This study evaluates how well the ecosystem model LandscapeDNDC is able to simulate observed emissions of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) from different tropical cropping rotations, i.e., double- and triple-cropped paddy rice, aerobic rice–paddy rice and maize–paddy rice (rice: O. sativa, maize: Zea mays) and how management changes to rice dominated lowland systems will affect the GHG balance on short (a few years) and long (several decades) time scales.