Development of Pedotransfer Functions for Penetration Resistance of Few Soils under Major Soil Orders of India

Pedotransfer functions for soil penetration resistance were developed for soils belonging to soil orders Inceptisols, Alfisols and Vertisols. For upland crops grown on Inceptisol and Alfisol, soil water content (SWC) along with bulk density (BD) accounted for nearly 72–85% variation in penetration resistance (PR). However, under saturated soil water conditions during lowland rice cultivation on Inceptisols and Vertisols, the correlation between PR and BD was between 64–78%. It was further observed that for most BD's, at lower SWC, PR was higher under Alfisols than Inceptisols but trend reversed at relatively higher SWC. Above developed pedotransfer functions are of great importance in calculating soil water content at 2MPa soil strength (SWC_2MPa) which is the soil water content below which plant experiences severe stress and is now being considered as the critical soil water content at which irrigation should be recommended. They are also useful in calculating the soil water stress period experienced by growing upland crops under different irrigation schedules. Computation of SWC_2MPa from above developed regression equations showed an increase with increase in bulk density and clay content. There was an increase of 4–5% in the value of SWC_2MPa at maturity over its value at initial stage.