Methodology for estimating the impact of no tillage on the 4perMille initiative: The case of annual crops in Spain

The 4perMille Initiative aims to mitigate anthropogenic CO2 emissions through carbon sequestration in soil organic carbon (SOC). Its main objective is to increase the annual amount of C in soils of the world by 0.4%. A new study methodology focused on achieving the regional objectives of 4perMille Initiative through No Tillage (NT) potential application in annual crops has been presented in this paper. It has been based on the modelling of Carbon Sequestration (CS) in Carbon Benefits Project (CBP), an online free tool. For the entire field of study (15 regions in Spain), the annual average is 0.38 Mg of C ha(-1) yr(-1). And the potential CS amounts are almost up to 3 Tg of C per year. CBP is a digital tool which allows to make an online modelling of the evolution of C stocks and Greenhouse Gas (GHG) emissions, derived from using different soil management systems. The comparison between the annual CS through NT and the contents in SOC in annual crops, has allowed to calculate the potential importance of NT, within the regional framework, of the 4perMille Initiative. There are large areas where the stored C could be 2 and up to 3 times over the reference values. What entails that the potential application of NT would represent a significant percentage of the CS objectives of the 4perMille Initiative in Navarra (52%), Castilla-La Mancha (51%), Castilla y Leon (43%), Aragon (35%), La Rioja (35%), Andalucia (35%) and Cataluna (29%). This methodology for calculating the NT potential over the 4perMille Initiative can be easily replicated in regions and countries around the world.