Spatial variability of organic carbon, available potassium and phosphor in Eslamabad Gharb agriculture research station, Kermanshah province

Accurate information about spatial distribution of soil nutrients and application of fertilizer is important in modern agriculture. Ordinary kriging was used to map of organic carbon، available phosphor and potassium in Eslamam-abad agriculture research station. Soil samples were collected on 50m*50m grids and analyzed for organic carbon، available phosphor and potassium. Results showed that distribution of organic carbon and available potassium data are normal but Logarithmic transformations were used for available phosphor content to fit it in normal distribution. The best semivariogram model for organic carbon was spherical model. Semivariogram of available phosphor and potassium data were fitted by exponential model. Variogram analysis indicated that spatial dependence for organic carbon and available potassium is moderate (nugget to sill ratio is between 25 % and 75 %) and spatial dependence of available phosphor is strong (nugget to sill ratio is less than 25 %). Ranges of variogram for organic carbon، phosphor and potassium are 579، 5058 and 588 m respectively. Kriging maps showed spatial variability for three soil fertility properties. Fertilizer recommendations based on Kriging maps provided optimal application of fertilizer and reduced bioenvironmental risks.