There has been low uptake of soil fertility improving tree technologies that have been promoted as alternatives to the costly inorganic fertiliser among the poor resource farmers of Sub Saharan Africa. This is surprising given that the majority of smallholder farmers cannot afford inorganic fertilisers. Are these technologies effective? Using data collected in 2013 from 1,231 households across six districts of Zambia, this study showed that the tree technologies increased maize productivity. However, increases in maize productivity were less than those obtained from controlled on-station and field experiments where the technologies could double or more than double maize productivity according to literature. The technologies capacity to marginally contribute to wealth creation was confirmed. Socioeconomic constraints including labour, information access, land and credit need to be tackled for the technologies to give maximum benefits. Research on fertiliser trees should therefore be redirected towards the discovery of such resource constraints saving technologies.