Long term impact of residue management on soil organic carbon stocks and nitrous oxide emissions from European croplands

Abstract

Application of crop residues to agricultural fields is a significant source of the greenhouse gas nitrous oxide (N₂O) and an essential factor affecting the soil organic carbon (SOC) balance. Here we present a biogeochemical modelling study assessing the impact of crop residue management on soil C stocks and N₂O fluxes for EU-27 using available information on soils, management and climate and by testing various scenarios of residue management. Three biogeochemical models, i.e. CERES-EGC, LandscapeDNDC and LandscapeDNDC-MeTrx, were used in an ensemble approach on a grid of 0.25° × 0.25° spatial resolution for calculating EU-27 wide inventories of changes in SOC stocks and N₂O emissions due to residue management for the years 2000-2100 using different climate change projections (RCP4.5 and RCP8.5). Our results show, that climate change poses a threat to cropping systems in Europe, resulting in potential yield declines, increased N₂O emissions and loss of SOC. This highlights the need for adapting crop management to mitigate climate change impacts, e.g. by improved residue management. For a scenario with 100% residues retention and reduced tillage we calculated that in average SOC stocks may increase over 50-100 years by 19-23% under RCP8.5 and RCP4.5. However, complete retention of crop residues also resulted in an increase of soil N₂O emissions by 17-30%, so that climate benefits due to increases in SOC stocks were eventually compensated by increased N₂O emissions. The long-term EF_N2O for residue N incorporation was 1.18% and, thus slightly higher as the 1% value used by IPCC. We conclude that residue management can be an important strategy for mitigating climate change impacts on SOC stocks, though it requires as well improvements in N management for N₂O mitigation.