Browsing by Author "Araki, Shigeru"

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Characterization of volcanic ash soils in south-western Tanzania: morphology, physicochemical properties, and classification
(African Study Monographs, 2007-03) Msanya, B. M.; Otsuka, Hiroo; Araki, Shigeru; Fujitake, Nobuhide
ABSTRACT This study examined the characteristics of volcanic ash soils in southwestern Tanzania. Twelve pedons of volcanic origin were studied, and 66 soil samples were analyzed. Soil morphology revealed volcanic ash layers of varying thicknesses. Most pedons had a dark thick humus surface and buried A, AB, and BA horizons with melanic indices of 1.7 or less. Except in two pedons, the NaF pH was 9.4 or more, reflecting an exchange complex domi- nated by amorphous materials and/or Al–humus complexes. The phospate-retention capacity ranged from 65 to 100%, except in two pedons, and was positively correlated with NaF pH. Both Tanzanian and Japanese volcanic ash soils showed comparable ranges of base saturation (BS) values, but the distribution patterns of BS basic cations, for example, showed some dif- ferences. Some Tanzanian volcanic ash soils had higher BS values than their Japanese coun- terparts. While the Japanese soils were generally more calcic and magnesic, the Tanzanian soils were more potassic and sodic than their counterparts, most likely reflecting lithologi- cal differences among parent materials in the two study areas. According to the USDA Soil Taxonomy, nine pedons satisfied the requirements for andic properties and were classified as Andisols at the order level, whereas according to FAO World Reference Base (WRB) soil classification, eight pedons were classified as Andosols at the level of reference soil groups.
Pedological characteristics, general fertility and classification of some benchmark soils of Morogoro district, Tanzania
(African Network of Scientific and Technological Institutions, 2003-12) Msanya, B. M.; Kaaya, K. A.; Araki, Shigeru; Otsuka, Hiroo; Nyadzi, Gerson, I
A detailed characterization of soils earmarked as “Benchmark Soils of Morogoro District”, Tanzania, was carried out to provide data required for planning and execution of soil fertility studies and transfer of agro-technology in the area. Benchmark soils are defined as those occurring in extensive areas and whose comprehensive characterization could contribute substantially to transfer of agro-technology from one area to another. Eleven sites were selected as “Benchmark Sites” of the district based on existing soils information coupled with reconnaissance field soil survey. Soil samples representative of the benchmark soil profiles were described and analysed for their chemical, physical and mineralogical characteristics. Based on these data, general fertility is discussed for the various soils pointing out their potentials and constraints. The data also permitted classification of the soils using international soil classification systems i.e. the United States Department of Agriculture Soil Taxonomy and the FAO-UNESCO Soil Classification System. The soils were classified into different categories reflecting their differences in potentials and constraints and hence use and management. The data obtained through this study presents a substantial base for sound land use planning and will facilitate transfer of technology from one area to another with similar ecological conditions.