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In order to analyse the spatial variabiltity of particle size distribution, organic matter, available phosphorous and potassium in long-term plot fields (treated with potassium, phosphorous and nitrogen at different levels) and potassium plot fields (uniform fertilizer application), soils were sampled in rectangular grids. Results have shown, in spite of small area in both cases, variations not only depend on the place but also on geographical direction (non-isotropic). All variables except avaialable phosphorous followed a linear semivariogram model. The available phosphorous showed nugget effect model
indicating the presence of random variation corresponding to its distribution with in trial treatment. Organic matter and available potassium weren't affected by fertilizer applications in long-term plots and showed spatial dependence due to physiographic conditions and probably irrigation method. The extent of soil heterogenity causing the adoption of random complete
block design was not lit for variance analysis and emphasized the necessity of
use of covariance analysis methods. Silt and clay variables emphasizes showed high nugget variance in both fields indicating more random than symmetrical variations in toal variance. Sand, available potassium and organic matter
followed spherical semivariogram model, their ranges were 19, 11, 15 metter, respectively. As far as these distances, variations were spatial and systematic whiele after that random. Therefore, these distance are economically leasible for sampling and are also of adequate precision.