The AGSUS protocol: bringing science to practice.

For attaining the sustainable development goals, soil conservation and/or regeneration is fundamental and new ways of engaging farmers in carbon projects that besides the prospect of benefitting from carbon credits delivers capacity building and guidance are required. Our objective was to develop and implement a MRV protocol for carbon sequestration and sustainable soil management certification that is based on the current state of knowledge and is attractive and viable for farmers to join these projects. We also considered specifically the way soil scientists, farmers and consultants develop a durable transdisciplinary team for co-learning and co-developing new soil management schemes that promote soil health and ecosystem services. We included the sustainable soil management certification because this ensures that the benefits will not be restricted to the eventual financial gain by selling carbon credits but engages the farmers in a change of attitude towards their soils, promoting more durable effects of changing agricultural practices. These certificates can also become more valuable in the future when markets recognize the need to comply with the SDG and will pay higher prices for sustainably produced food and the maintenance of healthy soils. The method comprises the annual Visual Evaluation of Soil Health (EV) and every five years SOC and texture determination on soil samples taken at 0-10 and 10-20 cm depth. We analyzed a database of all baseline certified farm sampling points (n= 546), representing more than 35.000 ha in Argentina. Overall, 3% of the soils had a "poor", 79% a "moderate", and 18% a "good" VE score. This is probably related to the mentality of the participating farmers who are probably more convinced of soil conservation and regeneration practices than the average farmer. Carbon stocks at these sites were related to the EV scores, with average values of 18.3, 15.5, and 14.6 g/kg for EV good, moderate and poor, respectively. While the organic matter index varied from 6.0, 5.4, and 4.2 for the same EV categories. This showed that there is a relationship between EV scores the OM index and SOC contents, which validates the VE as a monitoring tool that will reflect changes in SOC due to soil management. The yearly EV monitoring also provides the basis for the relationship between farmers and the organization which promotes the project and provides decision support and capacity building for the participating farmers.