ModelingWithin-field Soil Variability and Its Potential Use in the Variable-rate Treatment of Experimental Plots

This study described the soil variability in an experimental 10×10 m plot in Zanjan Province. The study was aimed at: (i) characterizing the short-range spatial variability of soil properties that control soil fertility and plant nutrition, (ii) delineating uniform areas within trial sites based on spatial dependence of soil properties, (iii) determining if this variation is large and can be managed at practical scales. Surface soil samples (0-30 cm) were analyzed for clay, silt and sand contents, calcium carbonate equivalent, pH, organic carbon, available phosphorus and available potassium. The spatial variability of soil properties was described using geostatistics. Sampling on a 1 m2 grid, revealed a relatively large spatial variability of soil properties. Clay content exhibited no spatial dependence but other variables investigated were well-described with variogram models and significant short-range variations depicted. Based on the geostatistical analysis, a stratification of the field into potential management zones was possible.