Roles of grasslands in sustainable improvement of land productivity in Bukoba District, Tanzania

This study was conducted in Bukoba District where land shortage and poor soil fertility are predominant thus limiting the productivity of the land. In this farming system, grasslands form an integral part in land productivity. However, changes in land tenure systems particularly for grasslands in recent years have undermined the functionality of the agro-ecological system. This study was designed to explore the roles of grasslands in sustainable improvements of land productivity through intensification of three predominant land use types namely Kibanja, Kikamba, and Rweya. Research methods involved interviews, group discussions, and retrieval of archival information on changing tenure systems; field experimentation and model development. Data were analysed for descriptive statistics, principal component analysis, ANOVA and modelling by SPSS, Conoco, GENSTAT and GAMS, respectively. Results established that customary tenure and land use practices have been destabilized by changes aimed at privatization of grasslands. Characterisation of farming households revealed three virtual farm types (FT) distinguished by: soil fertility management strategies, food security, and farm and off-farm income being important indicators of variability. All FT were found to be net food buyers annually. Grassland productivity revealed annual biomass production of 7.4 t ha-1 and 7.1 t ha-1 at high and low rainfall zones, respectively. The nutritive qualities of grasses were generally low throughout measurement period, although was better during first six months after burning implying the best grazing phase. Sustainability options for the three virtual FT showed that Kibanja productivity can be maintained in the absence of cattle provided that sufficient area of Kikamba to grow herbaceous legumes for supplying adequate N and K for optimum Kibanja productivity. Farm labour were found amounting to only 35%, 25%, and 39% of the available family labour for FT1, FT2, and FT3, respectively, implying presence of excess labour that could be allocated to off-farm activities. These findings imply that the productivity of Kibanja could be sustained even in absence of cattle provided there is sufficient land area for Rweya and Kikamba accessible to farming households