Distribution of soil organic carbon in a part of Gilan Province, Iran

Soil quality and fertility are affected by soil organic carbon (SOC). Management of SOC can reduce soil erosion and improve crop productivity. Accurate estimation of SOC variability could provide reliable information for understanding nutrients cycling and sediment. Therefore, the present research was aimed to investigate the spatial variation of soil organic carbon in Sefid-Rood river delta. In this regard, soil sampling was performed from 0-30 cm soil depth with their GPS-based coordinates. SOC values for 200 soil samples were measured using standard methods. For geostatistical analyses, semivariogram were developed and then the suitable theory model fitted to the experimental semivariogram. The information generated from the fitted model was applied to make use of ordinary kriging to estimate the value of organic carbon in the unknown locations. Cross Validation technique and statistical parameters of RMSE, MAE and MBE were also used. According to the results, the Gaussian model was selected as the best-fit model for the semivariogram with an effective radius of 3.64 km, a nugget effect of 0.17% and a sill of 0.48 was selected. The obtained results showed that the less SOC mostly in the south and northwest of the study area. In these parts, manure can be used to increase soil organic carbon.

Keywords:

Kriging , soil organic carbon , spatial distribution