Background
OCP Africa has asked a consortium consisting of ISRIC - World Soil Information, Wageningen University & Research, and the Nutrient Management Institute, in cooperation with AfricaRice, to cooperate with OCP Africa in the development of site- and crop-specific fertilizer formulations for important agroecosystems in Sub-Saharan Africa. To achieve this, it was agreed that, as a result of a longer term cooperation, the consortium will ultimately develop a broadly applicable soil fertility and crop nutrient management platform that can be used to produce maps of fertilizer recommendations for Sub-Saharan Africa based on nutrient gap analysis for specific crops in specific conditions.
Objectives
The consortium will develop and test targeted fertilizer recommendations for irrigated rice in the Office de Niger in Mali and the Senegal River Valley and Delta in Senegal to assess the feasibility of the methodology and provide a proof-of-concept.
Detailed maps of fertilizer recommendations will be developed using (semi-) mechanistic agronomic models and machine learning techniques combined with new and existing field data and model parameters. This will be done in collaboration with Office du Niger and IER in Mali and SAED and ISRA in Senegal. The resulting maps will enable project partners to define a number of area-specific fertilizer formulas (blends) which can then be produced and tested. The new area-specific fertilizer products will be tested in on-farm field trials relative to default blanket recommendations. The fertilizer recommendations themselves and the scientific methods used to develop them will be evaluated based on the resulting data.
Activities and results
The soil sampling campaigns were conducted in Mali and Senegal in 2018 after which the samples where analyzed by ICRAF in Kenya. The resulting data were used to produce detailed soil maps of the project areas.
The modelling framework itself was prepared, parameterized and tested in 2018 and used for nutrient gap analysis to produce site-specific fertilizer recommendations including N, P, K, Cu, Zn, B and S. These recommendations were generalized into six area-specific fertilizer formulas (three in each country) and these formulas were subsequently used by OCP to produce six new fertilizer products. These new fertilizers were tested in 2019 through an experimental campaign including 6x60=360 on-farm validation trials.
The area-specific new fertilizers proved to significantly outperform the blanket fertilizer in Mali and Senegal with on average 700 - 1000 kg/ha higher grain yields (within 95% confidence limits of 500 - 1500 kg/ha). This corresponds with additional yield responses of on average 60 - 120 %. The frequency of outperformance was above 90% in Mali and above 70% in Senegal.
(Note that above results for Senegal represent the effectiveness of only 1 out of 3 fertilizers. The other two are currently (2021) tested by 2x60 trials that have been reinstalled).
Funding
Funding for the project is provided by the OCP Group.