Towards Expansion of Coffea canephora Production in Tanzania: The Land Suitability Perspective

Abstract

As an effort to generate information that can be used to expand the Robusta coffee production in Tanzania, a study was conducted in six potential districts (Geita, Sengerema, Kibondo/Kakonko, Kasulu/Buhigwe, Uvinza and Mpanda) and two reference districts in Kagera (Muleba and Karagwe/Kyerwa) to assess the quality of land in general and soil fertility in particular. A total of 354 soil samples were taken from 116 survey sites across the study districts and were analyzed for routine soil fertility parameters. Land evaluation (qualitative, parametric method) was done, with climatic data adopted as proxy from nearby weather stations; and other land characteristics (slope, drainage and soil depth) taken from the field. In fertility assessment, soil pH was used to establish the correction factors for available N, P and K (fN, fP and fK). Then relationships were empirically worked out between the correction factors, OC and the amount of total N, available P and exchangeable K to get the total available forms of each in kg ha-1 which were converted to kg-equivalent (kE) per ha and summed up. Spatial interpolation was done using the inverse distance weighting (IDW) algorithm under QGIS 3.2. Geita and Sengerema compared fairly well with the reference districts in land suitability for Robusta. In the soil’s point of view, they showed to be even more fertile than the reference districts. They are hereby recommended as priority areas in Robusta expansion with the Robusta type of choice being Nganda which appears to be specific to the lacustrine ecosystem. The other four districts could constitute Phase two of the expansion. And because they are farther away from Lake Victoria, investors can adopt the Erecta type which appears to be better adapted to a diversity of agro-ecosystems.