International audienceThe ‘4 per mille Soils for Food Security and Climate’ was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New Zealand, Chile, South Africa, Australia, Tanzania, Indonesia, Kenya, Nigeria, India, China Taiwan, South Korea, China Mainland, United States of America, France, Canada, Belgium, England & Wales, Ireland, Scotland, and Russia). We asked whether the 4 per mille initiative is feasible for the region. The outcomes highlight region specific efforts and scopes for soil carbon sequestration. Reported soil C sequestration rates globally show that under best management practices, 4 per mille or even higher sequestration rates can be accomplished. High C sequestration rates (up to 10 per mille) can be achieved for soils with low initial SOC stock (topsoil less than 30 t C ha⁻¹), and at the first twenty years after implementation of best management practices. In addition, areas which have reached equilibrium will not be able to further increase their sequestration. We found that most studies on SOC sequestration only consider topsoil (up to 0.3 m depth), as it is considered to be most affected by management techniques. The 4 per mille number was based on a blanket calculation of the whole global soil profile C stock, however the potential to increase SOC is mostly on managed agricultural lands. If we consider 4 per mille in the top 1m of global agricultural soils, SOC sequestration is between 2-3 Gt C year⁻¹, which effectively offset 20–35% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration buys time over the next ten to twenty years while other effective sequestration and low carbon technologies become viable. The challenge for cropping farmers is to find disruptive technologies that will further improve soil condition and deliver increased soil carbon. Progress in 4 per mille requires collaboration and communication between scientists, farmers, policy makers, and marketeers

No abstract

No abstract

Proposed legislation to secure and maintain soil quality in Europe has generated interest surrounding how best to characterize soil geochemistry, and how to assess and monitor soil contamination. Visible-near infrared (vis-NIr), mid-infrared (MIr), and portable X-ray fluorescence (pXrF) spectroscopy can reduce time and cost associated with new soil monitoring programs. Before becoming deployable, accuracy of these techniques needs to be quantified. This study investigated potential of these techniques to characterize a full suite of soil geochemistry (40 elements), pH, and soil organic carbon (SOC) in a diverse set of agricultural soils from the Irish National Soil Database (NSDB) archive. Cubist models were employed to assess goodness of fit from spectrally derived estimates of each soil property. Then a model ensemble, or model averaging, approach was tested to examine if combining model outcomes of either vis-NIr or MIr with pXrF could improve accuracy of soil property prediction. In total, 15 of the 42 soil properties could be predicted to a good accuracy status using individual spectral methods, mostly achieved by MIr and pXrF. Combining model outcomes of vis-NIr or MIr with pXrF resulted in a positive improvement, increasing the number of soil properties that could be predicted from 15 to 25. Most notably is the large number of trace elements (As, Cd, Co, Cu, Hg, Mn, Ni, and Zn) predicted to good or reasonable accuracy. It was concluded that the synergistic use of vis-NIr, MIr, and pXrF spectral methods is well placed as a tool to permit large scale routine soil monitoring.Abbreviations: ICP, inductively coupled plasma; IQ, interquartile range; MIR, midinfrared; NSDB, Irish National Soil Database; pXRF, portable X-ray fluorescence; RPIQ, ratio of performance to inter quartile distance; SOC, soil organic carbon; vis-Nir, visiblenear infrared.T he strategy for protection of soils in Europe (European Commission, 2006a) recognizes a number of degradation processes or 'threats' to important soil functions. Among these is soil contamination arising from the introduction of substances on/in the soil that hamper soil functions, or present risks to human health or the environment. Proposed legislation for the protection of soils in Europe outlines a plan for member states to identify contaminated sites and introduce a program of remediation (European Commission, 2006b). A lack of legislation for soil protection in Europe (aside from the Directive on the management of waste from extractive industries [European Commission, 2006c]) makes regulation of contaminated sites difficult ( Jones et al., 2012). In the 39 countries of the European Environment Agency, the total number of contaminated soil sites in 2011 was estimated to be 2.5 million. The key sources of soil contamination arose from waste disposal and treatment, industrial, and commercial activities (e.g., mining, oil extraction, and power plants), storage (e.g., oil, oil extraction, and obsolete chemicals), transport spills on land (e.g., oil and other hazardou...