Estimation of Organic Carbon Loss Potential in a Climosequence in Golestan Privence, Northern Iran.

Soil organic matter (SOM) can be divided into labile or rapidly decomposed, and stable or slowly decomposed fractions. The most labile components of SOM include cellular contents such as carbohydrates, amino acids, peptides, amino sugars and lipids. Soil carbon oxidized by neutral KMnO₄, or permanganate-oxidizable carbon (POC), has been used as index of labile C by several workers, although the nature of organic C (OC) oxidized has not been well elucidated. The study area a climosequence (Udic-Xeric-Ardic regimes) with loess parent material in Golestan province, Iran. Samples from 7 different soil orders with pasture land use (Mollisols, Inceptisols, Aridisols and Entisols) were collected at (0-20 cm) depth. Permanganate-oxidizable carbon (POC) an index of soil labile carbon, was used to show soil potential loss of organic carbon. This index shows the maximum loss of OC in a given soil. Maximum loss of OC for each soil was estimated through POC and bulk density (BD). The potential loss of OC were estimated between 1930634 and 69180986 g ha^-1 Carbon. The lowest organic C loss was related to Entisols because of containing the lowest OC, and maximum potential loss of OC has been detected in Mollisols mainly due to having a lot of fresh organic tissue in mollic epipedon. In addition, the total amount of OC which were oxidised by KMnO₄ ranged from 14.41 to 59.43% of the total carbon. The effect of soil texture on soil permanganate oxidizable C (POC) was examined, clay + silt/OC, silt/OC and clay/OC accounts for 73%, 75% and 63%, respectively, of the variability in soil POC(P < 0.05). And also soil permanganate oxidizable C (POC) of 7 soil sample were regressed with their total C contents and were found to be highly correlated (R² =0.964, P < 0.01).