Variability of soil organic carbon with landforms and land use in the Usambara Mountains of Tanzania
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Date
2016-09
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Soil Science and Environmental Management
Abstract
This study was carried out to assist in the formulation of conservation technologies for landscape
sustained productivity in the Usambara Mountains, Tanzania. Conventional soil survey methods were
used to develop a base map on which 55 soil profile pits were randomly located on representative
landforms and land use mapping units. Soil samples were collected from topsoils for soil carbon
analysis using the wet digestion method. Descriptive statistics and linear regression models were used
to establish relationships between landforms, land use and soil organic carbon levels. Results showed
that carbon levels ranged between 0.55 and 10.8% for bush land and forest plantations in the plain and
plateau, respectively. Under cultivation, soil organic carbon (SOC) levels varied between 1.03 and 6.34%
for mid-slopes and lower slopes of the plateau respectively. The average soil organic carbon in the
vegetable growing valley bottoms was 4.5% while in the forest plantation was 5.5% with minimum and
maximum of 0.8 and 10.8% respectively. Linear regression model analysis indicated that factors
influencing variability of SOC apart from land use are: slope form, soil pH, electrical conductivity and
CECclay. It was concluded that soil organic matter in the study area is mainly determined by elevation,
slope form and type of land use and management. Introduction of soil erosion control measures and
incorporation of crop residues to areas where soil organic matter has been depleted were
recommended for sustainable crop production.
Description
Journal of Soil Science and Environmental Management 2016; Vol. 7(9): pp. 123-132
Keywords
Soil quality, Soil health, Topographic variation, Organic carbon.