Effect of land use system on soil carbon and selected soil properties in Mt. Elgon ecosystem, Kenya
Okwuosa, Elizabeth A.
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The aim of this study was to systematically quantify differences in soil organic carbon and key related soil properties in different land-use systems in Mt. Elgon Ecosystem, Kenya. Results show that soil organic carbon stocks varied significantly with depth (P<.OOl) and among land use systems (P<.OOI) with primary and secondary forests having higher soil organic carbon storage. Mean values for soil organic carbon stocks in primary forests were 61.5 t ha' , 48.67 t ha' and 34.34 tha' in the 0-10, 10- 20 and 20-30 cm depths, respectively while for plantation forests were 43.23 t ha', 38.72 t ha' and 26.4 t ha' in the same depths. Carbon concentrations in 0-10 cm soil depths in areas under by tea (49.05 t ha') were similar to those in-areas under plantation forest. Areas with a maize crop had low soil organic carbon stock, viz., namely 25.06 t ha', 37.30 t ha' and 39.75 t ha' in the three respective soil depths. The estimated depth -wise distribution of soil organic carbon stocks up to 30 em soil depth in the Mt. Elgon study sites was 41, 36 and 32% in the 0-10, 10-20 and 20-30 ern soil depths respectively. The total soil organic carbon stock in the soil up to 30 cm depth was estimated to be 6,688.4 Gt of carbon distributed at 59, 19, 11, and 10 % in natural forests, bamboo, plantation forests and tea plantations respectively. Land-use and soil depth had a significant effect (P<.OOI) on the total nitrogen levels in the order of primary forests> secondary forest> cultivated land-uses. Primary forests had 0.6,0.4 and 0.3 % N in the 0- 10, 10- 20 and 20-30 cm soil depths, respectively. Cultivated land had the lowest amounts of nitrogen compared to forest land-uses. The study concludes that natural and plantation forests have higher potential for carbon storage when compared to cultivated land-use systems. Keywords: Land use system, Soil Organic Carbon, Soil properties