African Cassava Agronomy Initiative (ACAI)

Background

Considered for long time as a food insurance and subsistence crop, cassava is increasingly a commercial crop with increasing demand by the food and feed industries. However, average yields are still low: about 10-11 Mg fresh storage roots ha⁻¹ in farmers’ fields in sub-Saharan Africa, against attainable yields of 50-60 Mg ha⁻¹ in researcher managed fields experiments. Key underlying constraints are the declining soil fertility and sub-optimal agronomic practices. The African Cassava Agronomy Initiative (ACAI) was established to develop and disseminate cost-effective technologies to sustainably improve cassava productivity in the short and long-term. ACAI is a 5 year project (2016 – 2020) operating initially in 2 countries in Africa (Nigeria and Tanzania). The project uses a demand-driven approach in developing agronomic solutions and extension tools for dissemination of improved fertilizer recommendations, best planting practices, intercropping, scheduled planting and cassava management for high starch content.

Objectives

The project aims to:

i) reduce yield gaps by generating basic information on cassava growth and nutrient requirements to enable the development of improved agronomic recommendations
ii) develop site specific fertilizer recommendations based on smallholder farmer resources and production objectives enabling farmers to reduce cassava yield gaps
iii) develop a decision support framework for extension service providers that allows large-scale dissemination of improved fertilizer recommendations and agronomic practices
iv) develop the scientific capacity for cassava agronomy within the national research systems.

IPNI’s role

IPNI is leading the fertilizer recommendation and fertilizer blending use cases within the framework of this project. The aim of the fertilizer recommendation use case is to participatory develop a decision support tool to derive site-specific nutrient management recommendations for cassava production based on site-specific agronomic conditions, production objectives, input/output prices and demand creation with service providers. To achieve this goal, nutrient omission trials have been established in major cassava production areas in these two countries: 143 in Nigeria and 117 in Tanzania in 2016. These trials were comprised of eight treatments: control, PK, NK, NP, NPK rep 1, NPK rep 2, half NPK and NPK+micronutrients. The latter treatment was included to assess micronutrient deficiencies. NPK treatment is replicated to assess the heterogeneity of the soil. The half rate NPK will be used for agronomic efficiency analysis. Data on non-destructive monitoring of cassava growth, as well as destructive harvests are being collected using Open Data Kit (ODK)-collect and field books. Soil samples have also been collected before or at planting for chemical and physical property analyses. Plant samples at harvest will also be analysed for chemical contents.