Sequestering soil organic carbon: a nitrogen dilemma
In this short perspective piece, researchers from the Netherlands, USA and the UK critically assess the COP21 4 per 1000 initiative, which seeks to increase global yearly agricultural soil organic carbon sequestration by 4‰ (= 0.4%, or 1.2 billion tonnes). The authors argue that as soil organic matter (SOM) also contains nitrogen (N), with a C-to-N ratio always approaching 12, this will require the sequestration of an extra 100 million tonnes of N per year, and they question the feasibility of achieving this.