Mitigation potential of soil carbon management overestimated by neglecting N2O emissions

International initiatives such as the ‘4 pour 1000’ are promoting enhanced carbon (C) sequestration in agricultural soils as a way to mitigate greenhouse gas emissions1. However, changes in soil organic C turnover feedback into the nitrogen (N) cycle2, meaning that variation in soil nitrous oxides (N2O) emissions may offset or enhance C sequestration actions3. Here we use a biogeochemistry model on approximately 8,000 soil sampling locations in the EU4 to quantify the net CO2 equivalent (CO2eq) fluxes associated with representative C mitigating agricultural practices. Practices based on integrated crop residue retention and lower soil disturbance are found to not increase N2O emissions as long as C accumulation continues (until around 2040), thereafter leading to a moderate C sequestration offset mostly below 47% by 2100. The introduction of N fixing cover crops allowed higher C accumulation over the initial 20 years, but this gain was progressively offset by higher N2O emissions over time. By 2060, around half of the sites became a net source of greenhouse gases. We conclude that a significant CO2 mitigation can be achieved in the initial 20-30 years of any C management scheme but, afterward, N inputs should be controlled through appropriate management.

LUGATO Emanuele;  LEIP Adrian;  JONES Arwyn; 

2018-11-15

NATURE PUBLISHING GROUP

JRC106969

1758-678X (online),   

https://www.nature.com/articles/s41558-018-0087-z#Sec11,    https://publications.jrc.ec.europa.eu/repository/handle/JRC106969,   

10.1038/s41558-018-0087-z (online),