The Soils4Africa project, funded under the EU H2020 programme, aims to develop a soil information system that serves information on the prevalence and spatial distribution of soil quality indicators and constraints relevant for sustainable intensification of agriculture in Africa, that can be used as baselines for monitoring changes in soil conditions in the future.
Soil samples are currently being collected at over 16,000 locations for two depths across agricultural land. Uniform procedures for fieldwork as well as lab analysis, combining wet chemistry with spectroscopy analyses, are used to ensure consistency. Here we present the sampling scheme designed for continental assessment and monitoring of soil conditions of the agricultural land in Africa. The design is a three-stage sampling design with stratified random sampling (with stratification based on farming system) in the first stage, and simple random sampling in the second and third stage. Using probability sampling allows model-free and unbiased estimation of the soil (health) parameters of interest of the sample population (or relevant sub-areas thereof such as for land cover types, agro-ecological zones, etc.) and their associated uncertainty. Additionally we will showcase the design and functionality of the emerging, continental soil information system that will eventually be hosted by an Africa-based institution. |