ISRIC Report 2015/02: Root zone plant-available water holding capacity of the Sub-Saharan Africa soil, version 1.0

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JGB Leenaars, T Hengl, M Ruiperez Gonzalez, J Mendes de Jesus, GBM Heuvelink, J Wolf, L van Bussel, L Claessens, H Yang and KG Cassman
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objective of this project is to produce a robust, quantitative framework, which is updateable and spatially explicit, to generate and maintain functional soil information on root zone depth and associated plant available soil water holding ca pacity for a major rainfed staple food crop (maize) in Sub-Saharan Africa. In most cases,
the rootable soil depth is considered to be an intrinsic soil property because it is difficult to modify the soil physical and chemical traits that restrict root growth, including high acidity or alkalinity, subsoil compaction, cemented layers, abrupt textural transitions, and bedrock. To achieve the project’s objective, a collaborative project was established among the Africa Soil Information Service (AfSIS) project and the Global Yield Gap and Water Productivity Atlas (GYGA) project, both funded by the Bill and Melinda Gates Foundation. Partners in the AfSIS project ( are Columbia Global Centers, ICRAF and ISRIC. Partners in the GYGA project ( are the University of Nebraska, Wageningen University, ICRISAT, and participating institutes and universities in ten Sub-Saharan countries. The collaborative project was led by ISRIC - World Soil
All soil data (field observations and laboratory measurements) and relevant covariate data (1km – 250 m resolution imagery), as generated by the AfSIS project and publicly available, are used to assess and map the plant-available water holding capacity of the effective root zone depth of maize
4. Maps of primary soil properties are interpreted for producing maps of functional soil properties, including soil moisture retention characteristics derived by pedotransfer functions and root zone depth derived from rules and thresholds as developed for this study. The resulting functional soil information for Sub-Saharan Africa is publicly available as a gridded dataset at 1 km resolution, referred to as version 1.0 of the Root Zone Plant-Available Water Holding Capacity dataset (RZ-PAWHC SSA v.1.0). The dataset is used by the GYGA project as input to simulation of crop yield potentials under water-limited (i.e. rainfed) production, including temporal variation, to estimate yield gaps in ten Sub
-Saharan countries. Summarizing, the collaborative work developed a consistent and updateable high-resolution soil information framework for agronomic modelling in support of both long- and short-term goals of smallholder farmers in SSA.The dataset is accessible at: