Soil climate regulation
International initiatives such as the ‘4 per 1000’ are promoting enhanced carbon (C) sequestration in agricultural soils as a way to mitigate greenhouse gas emissions. However, changes in soil organic C turnover feed back into the nitrogen (N) cycle , meaning that variation in soil nitrous oxide (N2O) emissions may offset or enhance C sequestration actions. Here we use a biogeochemistry model on approximately 8,000 soil sampling locations in the European Union to quantify the net CO2 equivalent (CO2) 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 significant CO2 mitigation can be achieved in the initial 20–30 years of any C management scheme, but after that N inputs should be controlled through appropriate management.
Contact point: Emanuele Lugato; Arwyn Jones
The data are available for public use. In order to download the data (6 scenarios), please fill in the form.
Lugato, E., Leip, A., Jones, A. 2018. Mitigation potential of soil carbon management overestimated by neglecting N2O emissions. Nature Climate Change 8:219–223
Agricultural soils may act as a carbon source or sink depending of the complex inter-relations between the carbon (C) and nitrogen (N) cycles. To one side, plants uptake carbon dioxide from the atmosphere and stabilise it in the soil, generating a mitigation effect when C accumulated in the soil is more than the CO2 released back into the atmosphere. N inputs, used to sustain plant productivity, also exert a direct and indirect control on C turnover. To the other side, the amount and type of N (e.g. synthetic fertilizer, N fixing crops, manure etc.), affect the availability of substrates used by microbial transformations, which produce N2O (a powerful GHG!) as intermediate of biogenic reactions involving N cycle.
To examine the relationship between land management and the soil C and N cycles in agricultural soils, JRC scientists have set up a complex data-biogeochemistry modelling framework. The model, running in approximately 8,000 locations across the EU (Land Use and Coverage Area Frame Survey-LUCAS), can provide a wide range of ecosystem parameters and, hence, become a useful tool for orienting the policymakers in promoting a ‘climate-smart’ agriculture.
Flow chart showing the datasets utilized and their spatial resolution, the inputs derived, and the model integration.
The data N2O emissions from agricultural soils in Europe are available for download; please fill in the form.
Lugato E, Paniagua L, Jones A, de Vries W, Leip A . 2017. Complementing the topsoil information of the Land Use/Land Cover Area Frame Survey (LUCAS) with modelled N2O emissions. PLoS ONE 12(4): e0176111