Soil organic carbon variation in relation to land use changes: the case of Birr watershed, upper Blue Nile River Basin, Ethiopia

• Published in: Journal of ecology and environment 2018, 42(3), 42, pp.128-138
• Main Authors: Amanuel, Wondimagegn, Yimer, Fantaw, Karltun, Erik
• Format: Article
• Language: English
• Subjects: Agricultural land; Agricultural production; Agriculture; Carbon; Carbon sequestration; Climate change; Cultivated lands; Cultivation; Eucalyptus; Forests; Greenhouse gases; Land use; Markvetenskap; Organic carbon; Organic matter; Organic soils; Oxidation; Plantations; River basins; Rivers; Soil management; Soil properties; Soil Science; Sorghum; Stream flow; Tillage; Variance analysis; Watersheds; 생물학
• ISSN: 2288-1220; 2287-8327; 2288-1220
• DOI: 10.1186/s41610-018-0076-1

Background This study investigated the variation of soil organic carbon in four land cover types: natural and mixed forest, cultivated land, Eucalyptus plantation and open bush land. The study was conducted in the Birr watershed of the upper Blue Nile (‘Abbay’) river basin. Methods The data was subjected to a two-way of ANOVA analysis using the general linear model (GLM) procedures of SAS. Pairwise comparison method was also used to assess the mean difference of the land uses and depth levels depending on soil properties. Total of 148 soil samples were collected from two depth layers: 0–10 and 10–20 cm. Results The results showed that overall mean soil organic carbon stock was higher under natural and mixed forest land use compared with other land use types and at all depths (29.62 ± 1.95 Mg C ha− 1), which was 36.14, 28.36, and 27.63% more than in cultivated land, open bush land, and Eucalyptus plantation, respectively. This could be due to greater inputs of vegetation and reduced decomposition of organic matter. On the other hand, the lowest soil organic carbon stock under cultivated land could be due to reduced inputs of organic matter and frequent tillage which encouraged oxidation of organic matter. Conclusions Hence, carbon concentrations and stocks under natural and mixed forest and Eucalyptus plantation were higher than other land use types suggesting that two management strategies for improving soil conditions in the watershed: to maintain and preserve the forest in order to maintain carbon storage in the future and to recover abandoned crop land and degraded lands by establishing tree plantations to avoid overharvesting in natural forests.