Attempts have been made to quantify penetration resistance (expressed as cone-index) from soil water content (dynamic variable) and other state variables such as texture, bulk density and over burden pressure indexed by soil depth. Stepwise regression analysis showed that among one-variable models, only soil depth explained significantly the variation in cone index. The two-variable model, soil water content and depth explained 59 per cent variability. Inclusion of sand and bulk density in the model increased the coefficient of determination to 61 per cent. With square terms of depth, sand and bulk density, the model explained 80 per cent of variability in cone index and most of the points scattered around 1: 1 line. Partial correlation coefficient of depth and soil water content with cone index had almost same magnitude followed by that of sand and bulk density.
Cone index, water content, soil depth and texture
