Combining Tree-Crop Farming: Mimicking Farmers' Mixed Cropping and Land Fallowing Practices in Developing Sustainable Farmland Management System

Abstract: Growing population and climate changes exerts pressure on land productivity and forest resources. Emerging unsustainable practices such as shortened period of traditional smallholders' natural fallows, exploitative cultivation and extension of farms through opening new farmlands and harvesting of natural forests for fuel wood are threats to productivity and environment. This necessitates development of sustainable production and environmental management solutions. Tree and shrubs were grown for two seasons in association with maize to mimic traditional farmers' mixed cropping and land fallowing in south western Tanzania, which significantly increased soil fertility with concomitant doubling of maize yield and reducing households' drudgery through increasing accessibility to firewood. Trees, Acacia mearnsii and Calliandra calothyrsus provided on average 20t/ha and 10t/ha of fuel wood biomass sufficient for over 590 and 330 days requirement of a rural household, respectively. These trees were liked by households as fuel wood for their heating strength, smokiness, charcoal and smelling on burning. The results mean that scaling up and out in the local landscapes of trees-crops culture would substantially increase farmland productivity, while eliminating harvesting pressure on natural forests. Trees and shrubs wood biomass and crop residues are promising economic resources in development of small electric power plants in rural areas.