Fe(III) fertilization mitigating net global warming potential and greenhouse gas intensity in paddy rice-wheat rotation systems in China

A complete accounting of net greenhouse gas balance (NGHGB) and greenhouse gas intensity (GHGI) affected by Fe(III) fertilizer application was examined in typical annual paddy rice-winter wheat rotation cropping systems in southeast China. Annual fluxes of soil carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) were measured using static chamber method, and the net ecosystem exchange of CO2 (NEE) was determined by the difference between soil CO2 emissions (RH) and net primary production (NPP). Fe(III) fertilizer application significantly decreased RH without adverse effects on NPP of rice and winter wheat. Fe(III) fertilizer application decreased seasonal CH4 by 27–44%, but increased annual N2O by 65–100%. Overall, Fe(III) fertilizer application decreased the annual NGHGB and GHGI by 35–47% and 30–36%, respectively. High grain yield and low greenhouse gas intensity can be reconciled by Fe(III) fertilizer applied at the local recommendation rate in rice-based cropping systems.

► Update our knowledge of Fe(III) fertilization effects on SOC, CH4 and N2O emissions.
► Insights into a complete accounting of annual NGHGB and GHGI in typical farming systems.
► Fe(III) fertilizer increased N2O, but benefited for C sequestration and CH4 mitigation.