SPATIAL VARIABILITY OF SOME PHYSICAL PROPERTIES IN RICE CULTIVATED SOIL USING GIS

الخلاصةThe study area was selected in the Abbasia district of Najaf Province, which is confined between two longitude 32° 06 42.8 ° to 32 ° 07 57.2 ° North and two latitude 44 ° 25 ° 16.4 ° to 44 ° 24 30.5° east. Coordinates of Pedons study locations were determined by GPS. Eight Pedons were detected for soils cultivated with rice, the Pedons were described morphologically. As well as interfaces samples was obtained randomly to four equal depths of 25-0 cm, 50-25 cm, 75-50 cm, 100-75 cm, for the study of spatial variability for the properties of those soils, the variability of physical properties using geological statistics, clay was the most variance of all horizons. The effective distance (Range) ranged between 91 - 180 m, followed by sand with a distance of 134 - 318 m in both horizons Ap and C1, and silt in both horizons C2 and C3, the effective distance (Range) ranged from 167 to 249 m. The trait that was less variability is the apparent density, with the distance between 368-55 m. The appropriate statistical models to describe the variability of soil properties when the geological statistics uses, and it was the spherical model and the Circular model by 50% for each. It found that the appropriate technology for obtaining soil samples be represented more efficiently, Depending on the effective range value with a strong spatial dependence of all the studied properties. As the number of samples that were calculated by the randomization law for physical properties between 5-797 samples, but when using geological statistics, the number of samples varied 5-28 sample. The soil of the study was classified under the order of modern soil composition (Entisol), under sub order of river deposits (fluvents), the great group (Torrifluvents) and sub group (Typic Torrifluvents).