Soil organic carbon stock and retention rate among land uses along Didessa toposequence in humid Western Ethiopia

There is scarcity of scientific information on stocks and retention rate of soil organic carbon (SOC) among mixed farming systems in humid Western Ethiopia. The objectives of study were to determine the SOC stocks and retention rates along a 53-km long toposequence of Didessa watershed. The study was conducted in mixed farming systems (annual arable cropping, grazing, fallow, grassland, coffee agroforestry, eucalyptus agroforestry and mechanized irrigated sugarcane production) within an elevation range of 1273 to 2543 m above sea level. The results revealed that land use types greatly affected SOC stocks and retention rates in the upper 20 cm soil depth. The SOC stocks ranged from 9.27 to 13.5 Mg C ha−1 (0–20 cm) while the retention rates were 0.11, 0.20, 0.28, 0.31 and 1.14 Mg C ha−1 year−1 for coffee agroforestry, fallow, grazing, eucalyptus agroforestry and irrigated sugarcane production systems, respectively. The retention rates demonstrated that the different farming systems are potential source of C sinks. The study indicated that the farming systems are efficient in sequestering SOC and their benefits can be further adopted for their economic values, social significance, restoration of degraded land, and sequestration of carbon (C) in humid tropical Western Ethiopia.Peer reviewe