Understanding Cassava Yield Differences at Farm Level: Lessons for Research

Abstract

Cassava is an important food crop in Africa. A range of improved varieties and Integrated Pest Management (IPM) practices have been developed to increase and maintain its yields in response to emerging pest and disease problems. Much less attention has been given to Integrated Soil Fertility Management (ISFM) and agronomic practices. Wide cassava yield disparities between farmers exist. Using a farm typology approach and six case study sites in East Africa, yield differences between sites and farm types were quantified and factors contributing to the differences evaluated. Overall, yield differences were twice as large between sites (6 t/ha) as between farm types (3 t/ha), whereas within sites, cassava yield differences between farm types varied from 1.5 to 7.5 t/ha. While differences in agro-ecological conditions explain part of the variation found at site level, differences in management were important in explaining cassava yields between farm types. Richer households obtained significantly (p < 0.001) higher cassava yield (+3.2 t/ha) than poorer households. Hired labour input (p < 0.01–0.05), monocropping (p < 0.05–0.15) and timing of first weeding (p < 0.01–0.1) significantly explained yield differences between sites and farm typologies. Use of improved varieties was rarely linked to higher yield levels. Manure and/or inorganic fertilizer use was rarely targeted to cassava. To improve cassava production in Africa, more emphasis should be given to the development and dissemination of appropriate management practices and higher yielding varieties. Research for development efforts in cassava should take into account and benefit from differences in cassava production that exist between farm types, while not ignoring agro-ecological differences.