Bringing CSA practices to scale: assessing their contributions to narrow nutrient and yield gaps

Photo: P. Vishwanathan (CCAFS)
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Project description

In Sub-Saharan Africa, both the area of land under agriculture and the intensification of agricultural practices are expected to expand over the next few decades to meet the growing population’s food needs and preferences. Greenhouse gas (GHG) emissions from agriculture will also increase, but the increase in emissions can be tempered through widespread adoption of climate-smart agricultural practices.

The Crop nutrient gap project aims to substantially increase the productivity of maize-legume smallholder farming systems in Ethiopia, Kenya and Tanzania without substantially increasing GHG emission intensity, nitrogen pollution or other negative externalities by employing the “4R nutrient stewardship approach.” The 4R approach means applying nutrients using the right source, at the right rate, at the right time and in the right place.

To address the current gap in meeting crops’ nutrient requirements, the project will identify and assess climate-smart fertilizer management options and agronomic practices to develop site- and crop-specific fertilizer best management practices. The project will select, test, and pilot promising best management practices. Trade-off analysis of environmental and farm economic objectives and upscaling of detailed work at farm level are important components of the approach.

Successful practices will be rolled out to smallholder farmers through local extension services, CCAFS and partner networks, and the private sector, including fertilizer companies. The approach – and specific practices – will be shared widely with other countries when applicable, an important interest of the private sector.


Additionally in 2016, the project conducted an initial stakeholder consultation, resulting in collection of essential data for quantifying legume yield gaps, defining nutrient gaps and packages, selecting suitable trial sites and setting up joint trials. A generic protocol for calculating nutrient gaps was drafted and distributed among project partners, and a python program, based on the QUEFTS model, was developed to perform the calculations. So-called Technology Extrapolation Domains (TEDs) were defined based on biophysical (climate and soil) and socio-economic criteria (population and livestock density, market distance).


The project is led by Wageningen University & Research (WUR), in collaboration with the International Fertiliser Association (IFA), the University of Nebraska-Lincoln, Yara International and the International Maize and Wheat Improvement Center (CIMMYT).

Further information

For more information, please visit the direct project website at or contact project leader Martin Van Ittersum (WUR) at