محبوبه ضرابی

Geo-statistical science is one of the methods which is used for the spatial distribution of soil parameters. The purpose of this staudy was to investigate the spatial variability of macro-elements in some surface soils in two landuse (Range land and agriculture), of the shahzand area at Arak province. A total of 76 soil samples were randomly collected from a depth of 0-30 cm from the study area. Some physico-chemical properties and values of different froms of Potassium, available Phosphorous amount, Calcium, Maganesium, Sulfur and Nitrogen percentage were determined. Kolmogrov-Smirnov test was used to control the normality of these parameters. The concentration mean of Phosphorus, solution k+, exchang k, Nn structur k, Calcium, Magnesium, Sulfur and Nitrogen were achieved to 35/98, 70/81, 509/24, 119/22, 6099/42, 1/27, 2/41, 23/92 mg/kg and %0/45 respectively. All of the elements value have highest in rangeland than agriculture land use. The results showed that between exchangeable, nonexchandable and total potassium with clay percentage were significant regression.Variogram model and kriging methods have been spatical variability of these variable. The results of Geostatistial analysis showed that the spherical model with high R2 and lowest errore was proper model for interpretation of studied elements. The values of different Potassium froms in these soils were high and related to the presence of Illite, especially non exchangeable and structur Potassium. Result of zoning showed that amounts of solution, exchnagable, nonexchangable and total potassium were highest in north and west norht regions of the study lands. the values of Calcium, Magnesium and Sulfurs were related to lithogenic sources.Consequently, the results showed that geostatistical method could be trace spatial variability of macro-element and any soil propertie .