Pedological Approach for Soil Carbon Stock Estimating in Gayo Highland Coffee Plantations, Aceh-Indonesia

Soil carbon stocks (SCS) play a key role in regulating soil fertility and global climate. Determining the amount of SCS through a pedological approach is still limited, while the amount of SCS in highland areas based on elevation is still debated, also the role of elevation-slope combinations on SCS is not well known. This research aims to determine the amount of SCS in each soil horizon, elevation, slope position and also the effect of elevation and slope position on SCS.

A total of 46 undisturbed and disturbed soil samples were collected in each pedogenic horizon from 12 soil profiles at four elevation levels ie 700-715; 1000-1060; 1300-1351; 1600-1616 meter above sea levael (m.a.s.l.) and three slope positions (foot, middle, and upper of slope) in Gayo highland Arabica coffee plantation fields.

The results showed that SCS of soil horizons in Arabica coffee plantations in the Gayo highlands varied from 5.97 to 84.56 MgC.ha^-1, with SCS of the upper horizons being higher than those of the lower horizons. The amount of solum SCS from the soil profile also varied from 73.91 to 218.25 MgC.ha^-1. Based on the elevation, the highest mean amount of SCS of the solum was 157.35 MgC.ha^-1 which was found at the elevation of 1600-1616 m.a.s.l, whereas the mean amount of solum according to the slope position was 167.34 MgC.ha^-1 which was found on the foot of slope. Elevation and slope position significantly increased the SCS with the highest value found in the combination of 1000-1060 m.a.s.l, and foot of slope.