Effects of ‘‘Guie’’ on Soil Organic Carbon and Other Soil Properties: A Traditional Soil Fertility Management Practice in the Central Highlands of Ethiopia

A traditional soil fertility management practice through soil burning, locally called ‘‘guie’’ is practiced in the central highlands of Ethiopia. The study was conducted to investigate the effect of ‘‘guie’’ on physico-chemical properties of the soil and its long term impact on soil organic carbon (SOC). Two sets of soil samples were collected from the field. The first set was from central part of the heaps of the burnt soil. The second set was from adjacent cultivated fields used with and without ‘‘guie’’ for many years. Collected samples were analysed following standard laboratory procedures. Complete soil burning showed a significant decrease in SOC, total nitrogen, cation exchange capacity (CEC), exchangeable calcium, magnesium, sodium, available iron and clay while it significantly increased available phosphorus, manganese and copper, exchangeable potassium and sand. A significant difference (p<0.001) in SOC was also obtained for the second sample set. The highest (7.14%) and the smallest (1.54%) mean SOC was obtained from cultivated land where ‘‘guie’’ integrated with fallowing and without ‘‘guie’’ and fallowing, respectively. This indicates that fallowing could help the soil to accumulate SOC and if it coupled with the partial soil burning practice, accumulation of stable organic carbon in the soil could be enhanced. Intensive cultivation exposes the soil for erosion accompanied by active mineralization of the organic matter. Thus, results of the present study have an implication that fallowing integrated with ‘‘guie’’ is more sustainable to reserve OC in the soil system than the continuous cultivation.