Soil organic carbon and pH dynamics across land use types and altitudinal gradients in semi-arid Northern Tanzania
5 affiliations
- 1Department of Crop Sciences and Beekeeping Technology, University of Dar es salaam
- 2Department of Crop Science and Horticulture, Mbeya University of Science and Technology
- 3Department of Soil and Geological Science (DSGS), Sokoine University of Agriculture (SUA)
- 4Center for International Forestry Research and World Agroforestry Centre (CIFOR-ICRAF)
- 5School of Materials, Energy, Water, and Environmental Sciences (MEWES), Nelson Mandela African Institution of Science and Technology (NM-AIST)
Abstract
Despite growing evidence that land-use change and altitudinal variation influence soil organic carbon (SOC) and soil pH, integrated assessments examining their combined effects across multiple land-use systems and environmental gradients remain limited in semi-arid landscapes of northern Tanzania. This study assessed SOC (%) and pH across four land use types i.e., conserved land, cropping land, grazing land, and abandoned land in Arusha and Monduli Districts, northern Tanzania, encompassing lowland (< 1400 m), midland (1400–1600 m), and highland (> 1600 m) zones altitude categories. A total of 586 soil samples were collected across 2 Soil depth classes and analyzed for SOC (%) and pH. Results demonstrated that land use type was the dominant driver of both SOC and pH variability (one-way ANOVA: FSOC = 107.19, P = 2.95 × 10− 55; FpH = 48.68, P = 4.43 × 10− 28). Conserved land recorded the highest mean SOC (2.15 ± 0.35%) and lowest mean pH (6.48 ± 0.38), while abandoned land showed the lowest SOC (0.84 ± 0.20%) and highest pH (7.27 ± 0.42). Monduli District consistently outperformed Arusha District across all land use types, with overall mean SOC of 1.87% versus 1.18%. A strong negative correlation was observed between SOC and pH (Pearson r = -0.637; Spearman ρ = -0.653; P < 0.001), and altitude positively predicted SOC (r = + 0.59). Bonferroni-corrected post-hoc comparisons confirmed statistically significant differences in SOC between all six pairwise land use combinations. These findings show the critical role of land conservation, highland ecosystem protection, and active restoration of degraded soils in sustaining carbon stocks and soil health across semi-arid landscapes of northern Tanzania.
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BibTeX
@article{kalonga2026soil,
title = {{Soil organic carbon and pH dynamics across land use types and altitudinal gradients in semi-arid Northern Tanzania}},
author = {Joseph Kalonga and Marco Mng’ong’o and Boniface Massawe and Anthony Kimaro and Ann Winowiecki and Tor-Gunnar Vågen and Kelvin Mtei},
journal = {Discover Environment},
year = {2026},
month = oct,
doi = {10.1007/s44274-026-01149-6},
url = {https://doi.org/10.1007/s44274-026-01149-6},
note = {CC BY},
}
RIS
TY - JOUR
TI - Soil organic carbon and pH dynamics across land use types and altitudinal gradients in semi-arid Northern Tanzania
AU - Joseph Kalonga
AU - Marco Mng’ong’o
AU - Boniface Massawe
AU - Anthony Kimaro
AU - Ann Winowiecki
AU - Tor-Gunnar Vågen
AU - Kelvin Mtei
PY - 2026
DA - 2026/10/01
JO - Discover Environment
DO - 10.1007/s44274-026-01149-6
UR - https://doi.org/10.1007/s44274-026-01149-6
AB - Despite growing evidence that land-use change and altitudinal variation influence soil organic carbon (SOC) and soil pH, integrated assessments examining their combined effects across multiple land-use systems and environmental gradients remain limited in semi-arid landscapes of northern Tanzania. This study assessed SOC (%) and pH across four land use types i.e., conserved land, cropping land, grazing land, and abandoned land in Arusha and Monduli Districts, northern Tanzania, encompassing lowland (< 1400 m), midland (1400–1600 m), and highland (> 1600 m) zones altitude categories. A total of 586 soil samples were collected across 2 Soil depth classes and analyzed for SOC (%) and pH. Results demonstrated that land use type was the dominant driver of both SOC and pH variability (one-way ANOVA: FSOC = 107.19, P = 2.95 × 10− 55; FpH = 48.68, P = 4.43 × 10− 28). Conserved land recorded the highest mean SOC (2.15 ± 0.35%) and lowest mean pH (6.48 ± 0.38), while abandoned land showed the lowest SOC (0.84 ± 0.20%) and highest pH (7.27 ± 0.42). Monduli District consistently outperformed Arusha District across all land use types, with overall mean SOC of 1.87% versus 1.18%. A strong negative correlation was observed between SOC and pH (Pearson r = -0.637; Spearman ρ = -0.653; P < 0.001), and altitude positively predicted SOC (r = + 0.59). Bonferroni-corrected post-hoc comparisons confirmed statistically significant differences in SOC between all six pairwise land use combinations. These findings show the critical role of land conservation, highland ecosystem protection, and active restoration of degraded soils in sustaining carbon stocks and soil health across semi-arid landscapes of northern Tanzania.
SN - 2731-9431
ER -