The aim of the present study was to provide a better understanding of the degree and drivers of intensification of shifting cultivation and its effects on vegetation and soils. The study was conducted in uplands and low lands agro-ecological zones of Kilosa District, eastern central Tanzania. Data collection involved household survey, focus group discussions, soil and vegetation description and analysis of Landsat satellite images.
Results indicated intensified land use practices had occurred in the study area between 1995 and 2013. In the uplands, the number of shifting cultivators declined from 38% to 13% but the area under shifting cultivation slightly increased from 15% to 16%. In the lowland, shifting cultivators declined from 24% to 18% but the area substantially declined from 63% to 38%. In both agro-ecological zones, the shifting cultivators changed to permanent cultivation of annual crops and intensive short fallow systems. They also adopted intensive land preparation methods that involved deep cultivation and burying of vegetation. Intensification in upland was driven by adoption and enforcement of land tenure policies which restrict shifting cultivation whereas in the lowlands, it was driven by increase in population pressure on limited available land.
Furthermore, results indicated that intensification of shifting cultivation has contributed to 43.5% of the total deforestation, equivalent to a loss of 1848 ha/year. The intensification has also reduced the soil quality since the recovery of total N, plant-available P and exchangeable K significantly declined with shortening of fallow duration. The intensification has also negatively affected the recovery of Miombo woodland species composition, life form and abundance of the dominant tree species.
Based on these findings, I recommend that sustainable intensification of shifting cultivation be sought to prevent further adverse effects on the environment. The present restrictive policy driven approach of intensification of shifting cultivation seems to cause more negative environmental consequences. I recommend development and promotion of policies that create opportunities and advantages to farmers. The opportunities or advantages can be created through improvement of infrastructure-roads, access to agricultural inputs, credits, irrigation systems, modern farming equipment, secured market, protection of the individual rights to land and resources and provision of reliable agricultural extension service and information system.