American Journal of Agriculture and Forestry
2017; 5 (1): 1-11
This study was carried out in Kilombero District, Tanzania with the objective of characterizing the soils in terms
of their morphology, genesis, physico-chemical properties and classification. Three pedons KISA-P1, MKU-P1 and MBA-P1
were identified within the Kilombero Valley, dug, described and sampled. Disturbed and undisturbed soil samples were taken
from designated pedogenic horizons for physical and chemical analysis in the laboratory. Using both field and laboratory data
soils were classified using both USDA Soil Taxonomy and World Reference Base for Soil Resources schemes of classification.
Results show that the three pedons were developed under Isohyperthemic temperature and Aquic moisture regimes. All pedons
were deep (100 - 120 cm). Whereas Pedons KISA-P1 and MBA-P1 had sandy clay loam topsoils overlying sandy clay
subsoils, Pedon MKU-P1 had clayey texture throughout its profile depth. All pedons had low chromas of . 3 and
redoximorphic features in form of abundant mottles particularly in the subsoils. Topsoils of Pedons KISA-P1 and MBA-P1 had
dominantly friable to very friable moist consistence while those of Pedon MKU-P1 had very firm moist consistence. Subsoil
moist consistence varied from firm to extremely firm (Pedons KISA-P1 and MKU-P1) and from friable to very firm (Pedon
MBA-P1). Structures were dominantly weak to moderate subangular blocky in all studied soils but some horizons were
structureless single grained and massive. Soil reaction ranged from extremely acid (topsoil of MBA-P1) to mildly alkaline
(subsoil of MKU-P1) with pH values of 4.44 and 6.73 respectively. Topsoil organic carbon and total nitrogen contents in the
studied pedons were low (0.66 to 1.4%) and very low to low (0.08 to 0.19%) respectively. CECsoil values were rated as low to
medium ranging from 8.4 to 23.8 cmol (+)/kg respectively in Pedon KISA-P1 and Pedon MKU-P1. Percent BS values varied
between and within studied pedons and ranged from low < 50% to high > 50%. Studied soils manifested nutrient imbalances in
respect of basic cations. On the overall, fertility of the studied soils was rated as low to medium. According to USDA Keys to
Soil Taxonomy, Pedons KISA-P1 and MKU-P1 classified as Inceptisols, equivalent to Cambisols in WRB for Soil Resources
whereas Pedon MBA-P1 classified as Entisols equivalent to Fluvisols. All three sites were recommended for paddy production.