Pedogeomorphological Categorization of Selected Soils in Mbogo - Komtonga Irrigation Scheme, Mvomero District, Morogoro Region, Tanzania

Pedogeomorphological categorization of selected soil profiles developed on alluvial deposits in Mbogo - Komtonga traditional irrigation scheme, Mvomero District in Morogoro Region, was carried out during February 2017. Using standard grids, pedogeomorphic approach and standard manuals, detailed soil survey was conducted which enabled delineation of soil mapping units from which the representative profiles were identified, described and sampled. Eighteen samples were collected at a depth of 0–30 cm and from each horizon of the selected soil Master pits and analyzed for physico – chemical characterization. Based on FAO soil survey system of classification, the representative profiles were classified as Eutric Fluvisols and/or Eutric Cambisols. The pedon was deep to moderately deep, well to moderately well drained, with brownish black clay top soils or dull yellowish brown soil colors with sub soils stratified with fS, C, CL and SCL. Top soil pH was strongly to medium acid to medium or slightly acid sub soils. OC showed no decline in soil quality. N was very low to low, P and K levels were medium to low or very low; CEC was high to very high in all the profiles. Ca2+ and Mg2+ in the top soils were high to very high and very low or low to medium in the sub soils. Na+ was rated as low to medium in the top soils of all profiles and low to very low in the sub soils. Base saturation was > 50% and was rated as high. Topsoil Bd and total porosity were ideal to medium. AWC was medium and water storage capacity (AWSC) was good and sufficient for paddy production and other upland crops. These results suggest that where the soil parameters were low to very low as for N, P and SOM should be included in the overall soil fertility management program. Soil reaction may be regulated during irrigation development by provision of sufficient drainage, discharge and flood control structures and minimum application of lime if required.