Spatial variability of soil sampling for salinity studies in Southwest Iran

Summary This study addresses the technology for soil sampling of large agricultural fields which are inherently variable in both space and time. Three several hundred ha fields in southwest Iran initially sampled on an arbitrarily selected grid of 80 m to ascertain soil salinity levels were analyzed using both geostatistical and classical statistical methods. The results from two fields showed that the variance structure of the salinity observations were spatially dependent, and hence, geostatistical techniques allowed best linear unbiased estimates of salinity values interpolated between spatially observed sampling locations to yield contour lines of isosalinity. In the third field, salinity observations were found to be spatially independent, and hence, were analyzed by classical methods to yield the number of soil samples necessary to observe the fiducial limits within which it is expected that the true mean salinity exists for given levels of probability.