Spatial Variability of Penetration Resistance on Pseudogley

Usually large numbers of measurements are required to describe spatial variability of soil resistance but GIS technology with interpolations methods make it possible to estimate data from unsampled locations. In this paper cone index (CI) measurements were made in two occasions in 2.88 ha fi eld in central Croatia to present soil condition. A commonly used tillage operation consists of ploughing (about 30 cm depth) and disc harrowing (12 15 cm), and they are practiced on annual basis. Measurements (240) were taken according sample grid in 48 diff erent 24 x 25 m2 fi elds. Cone index (CI) data were interpolated using geostatistical techniques (ordinary kriging) to produce the maps of soil resistance. Th ese maps combined with expert knowledge can provide good direction for applying appropriate soil management. Our results demonstrate that the investigated layers had variable spatial structures in terms of their linear trends. Th is suggests that each layer has a unique spatial structure possibly as consequence of pedogenetic processes, tillage operations and changes infl uenced by drainage and leveling operations. Th e results presented here describe spatial variability of soil resistance of a drained Pseudogley of Central Croatia, measured as CI in a fi eld conditions. Tillage practices caused the formation of a plow pan at a depth 30 – 40 cm where the maximum CI values were obtained. According to the values of penetration resistance the tillage practices should be changed if we consider improved conditions for plant roots development.