No abstract

This paper examines the variability of rainfall and temperature in Igunga and Kishapu Districts using time series data (1985 to 2016) from Tanzania Meteorological Agency. The regression analysis results show rainfall variability of R 2 = 0.096 in Igunga and R 2 = 0.186 in Kishapu which implies that about 0.96% and 1.86% of the changes in rainfall across the districts are associated with changes in weather variables. A considerable change of amount of rains was evident in Igunga than in Kishapu District. In both districts there was a change of months with the most rains. Generally rainfall showed a decreasing trend in both districts. The paper also examined temperature trends in the two districts; the findings showed an increasing trend throughout October in both districts. From this point of view, higher temperatures can increase evapo-transpiration that in turn can have an effect on moisture for the crops adversely affecting pasture productivity for livestock, and leading to a shortage of water for both crops and livestock. Annual rainfall variability trends, however, increased indicating that annual variability was somewhat a common feature in the study districts. So, districts efforts should be directed towards the support of crop and livestock adjustments in order to buffer impacts of rainfall and temperature variability during critical periods for growing of crops and pastures.

Small-scale crop production in many parts of Tanzania is constrained by many problems among which soil fertility degradation is a major problem.Over 80% of cassava (Manihot esculenta) production in Tanzania is done by the small-scale farmers who continuously cultivate their fields, but use limited inputs to restore depleted plant nutrients. The objective of this study was to examine the best legume species that could be incorporated in cassava (Manihot esculenta) production systems under farmers' conditions and result in increase in soil fertility and crop yields. Mucuna pruriens and Canavalia ensiformis were either incorporated with cassava (Manihot esculenta) or planted as sole crop in rotation with cassava. Mucuna pruriens and Canavalia ensiformis were found to produce almost similar amount of biomass. The two legumes, however, produced higher biomass in rotation than intercropping system. The amount of biomass produced by Mucuna pruriens and Canavalia ensiformis in rotation system was 6.28 t•ha ). Intercropping and rotation of cassava with legumes increase cassava yield and represent a sustainable alternative to reduce the farms' dependence on external inputs and to enhance inherent soil fertility.

The technological transformations of smallholder agricultural systems that took place as part of the Green Revolution in Asia and Latin America in the second half of the twentieth century have been slow to take hold in sub-Saharan Africa (SSA). A history of low fertilizer use in SSA has led to widespread depletion of soil nitrogen (N) and other nutrients (Cobo et al., 2010;Vitousek et al., 2009), limiting crop productivity and contributing to the inability of many smallholders to break out of poverty (Barrett & Bevis, 2015). New efforts at agricultural intensification became a focus of international development and national policy in multiple African countries during the 2000s (Jayne & Rashid, 2013;Jayne & Sanchez, 2021). Many agricultural development practitioners have focused on restoring soil nutrients, increasing productivity, and alleviating poverty through the intensification of smallholder agriculture (AGRA, 2009). Although there is some debate about the

Titles in the Working Paper Series aim to disseminate interim results on agroforestry research and practices and stimulate feedback from the scientific community. Other publication series from the World Agroforestry Centre include the Trees for Change series, Technical Manuals and Occasional Papers.