Filling in the gaps on smallholder maize-legume farming systems to address farmer needs in Tanzania

"Smallholder farming systems in sub-Saharan Africa (SSA) are faced with the major sustainability challenge of increasing production on land with declining fertility. Legume intensification has been proposed as an important pathway for ecologically-sound, sustainably intensified production on smallholder farms, yet numerous challenges stand in the way of enhanced adoption and intensifying production of legumes. Promising legume technologies demonstrated on research stations often fail to be adopted on smallholder farms. Yet, this is where they are needed most. Legume production is a knowledge intensive enterprise, and as such requires effective extension systems. Addressing challenges in legume production requires understanding the disconnects between research and farmer practice in order for technologies to be developed and disseminated that fit within smallholder farming conditions.This dissertation consists of three studies focused on maize-legume cropping systems in Tanzania at different scales. An interdisciplinary approach was used to evaluate legume production through integrating field trials, on-farm assessments, and analysis of Tanzania extension systems. In the first study, 14 lablab (Lablab purpureus) accessions were evaluated by environment through a multi-site, multi-year field experiment using performance and biological nitrogen fixation measurements. This allowed for determination of suitability in sole and maize intercrop systems to identify appropriate accession types for Tanzanian smallholder farming systems. The second study used survey data from households across Northern and Southern highlands of Tanzania (n = 578) with linked soil samples to assess how soil properties and erosion signs are related to farmer perceptions and practices. Additionally, a subset of farms was used to test a new extension approach to quantify site-specific soil degradation, facilitated by the smartphone application LandPKS. In the third study, extension systems and sources of information were evaluated and compared to farmer practices associated with legume production systems to better understand connections and disconnects. Traditional extension and a novel approach involving village-based advisors were explored through mixed methods, including in-depth characterization of farmer legume production systems. Findings from each study highlight how to facilitate the sustainable intensification of legume production at different levels and address the multi-faceted needs of smallholder farmers."--Pages ii-iii.