Tropical Soil Carbon Stocks In Relation To Fallow Age And Soil Depth

The interest in Soil carbon has risen significantly in the science community due to the potential of climate change mitigation through soil carbon sequestration. Changes in fallow periods influence how much and at what rate carbon is sequestered in or released from the soil. Carbon sequestration in soils under three different fallow ages (7, 14 and 21) at varying sampling depths (0-20, 20-40, 40-60, 60-80, 80-100 cm) was investigated using the method of Batjes and data obtained were subjected to analysis of variance. Organic carbon content was generally low ranging from 3.99 – 5.67g kg-1. Soil carbon sequestered under the three varying fallow ages ranged from 1295 – 1611g cm-2. Though no significant variation was observed in the amount of C sequestered by the varying ages of vegetation, results showed that 14 years fallow sequestered the highest quantity of carbon (1611g cm-2) while the least (1295 g cm-2) was obtained in 7 year fallow. On the other hand, sampling depth had a significant influence on soil carbon content. In 7 years fallow period, 0-20, 20-40 and 40-60 cm sampling depths contained significantly highest carbon stock values. In 14 and 21 years fallow ages, 0-20 cm sampling depth sequestered significantly highest carbon (3147.04 g cm-2, 2247 g cm-2) compared to other sampling depths. Conclusively, more carbon is sequestered at the soil surface than in the sub-soil and prolonged fallow age up to 21 years may not be beneficial to soil carbon sequestration.