An integrated methodology using open soil spectral libraries and Earth Observation data for soil organic carbon estimations in support of soil-related SDGs

There is a growing realization amongst policy-makers that reliable and accurate soil monitoring information is required at scales ranging from regional to global to support ecosystem functions and services in a sustainable manner under the amplifying climate change enabling countries in target setting of the Sustainable Development Goals (SDGs). In this line, the need of access to and integration of existing regional in situ Earth Observation (EO) data and different sources such as contemporary and forthcoming satellite imagery is highlighted. The current study puts major emphasis on leveraging existing open soil spectral libraries and EO systems and bridging them with memory-based learning algorithms that create more cost-efficient and targeted large scale mapping of soil properties. Relying mostly on contemporary capacities and open resources it can be readily applied to countries with differing capacities and levels of development. To test our methodology, the GEOCRADLE SSL developed in the Balkans, Middle East, and North Africa region and a hyperspectral airborne image were utilized to provide Soil Organic Carbon (SOC) maps of cropland fields over an agricultural region near the city of Netanya, Israel. Furthermore, simulated data of forthcoming space-borne satellite (EnMAP) and current super-spectral mission (Sentinel 2) were explored. The SOC content of the collected in situ soil samples was predicted using a novel local regression approach that combines spatial proximity and spectral similarities. These predictions were subsequently used to develop models using the airborne and simulated satellite spectra, achieving a fair prediction accuracy of R² > 0.8 and RPIQ>2.