Tanzania Agricultural Research Institute

Author(s) : Catherine J Senkoro1, George J Ley1, Atanasio E Marandu1, Charles Wortmann2, Muhamadi Mzimbiri3, Joh

Most croplands of Tanzania have low fertility and nitrogen is the most limiting nutrient (Mowo et al., 1993; Marandu et al., 2014). Soil phosphorus availability is commonly low. Potassium and S deficiencies are locally important. There are occasional indications of localized Cu, Zn and Mn deficiencies. Current fertilizer use is reported to average 17 kg/ha/yr with most used for maize, rice and vegetable production (World Bank 2014). In 2008, a subsidy on fertilizers and seeds was introduced under the National Agricultural Input Voucher Scheme (NAIVS) to promote adoption of improved seed and fertilizers, especially for high potential maize and rice production and fertilizer use has increased from 9 to 17 kg/ha/yr since then. Generally less than 5% of farmers in 50% of the districts use fertilizers. MAFS (2012) indicated that 42% of fertilizer is used in the Southern Highlands, 17% in Shinyanga and Tabora Regions, 12% in Kilimanjaro and Arusha Regions, 10% in Morogoro Region and 5% in Kagera and Kigoma Regions. Urea accounts for about 65% of fertilizer usage. Traditional soil management practices include incorporation of crop residues, fallow, use of farmyard manure, and inter-cropping or rotation of legumes and non-legumes (Shekiffu 2011). Most farmers, however, harvest or burn crop residue. In Eastern Zone, almost 70% of the farmers in cassava based production systems burned crop residues during land preparation, 12.5% farmers incorporated crop residues, 16.5% fallowed land for 1 to 3 years, 2.5% used farmyard manure, and none used fertiliser (Shekiffu 2011). In Northern Zone, crop residues are commonly burnt or harvested with no significant incorporation of organic material into the soil to maintain topsoil structure and nutrient status. The first fertilizer recommendations were issued in 1982 for 20 AEZ and later adapted to a district basis (Harrop and Samki 1984.based on results of fertilizer trials conducted by different institutions (Mowo et al., 1993). World Bank supported a project to update fertilizer recommendations for rice and maize in some AEZ in 2009 to 2012 (Marandu et al., 2014) with differentiation for production potential, e.g. the N recommendation for lowland rice in high potential (HP) areas like Mombo irrigation scheme is 120 kg N/ha but 80 kg/ha for rainfed lower potential areas.