Q91: Find out the value of $\text{pF}$ when there is a... - Pedology, Soil Physics, Soil Colloids, Problem Soils & Water Quality - ICAR AIEEA PG Physical Science 14 July 2023 Shift-1 Paper | Agrigyan

The concept of $\text{pF}$ was introduced by R. K. Schofield (1935):

• Definition: $\text{pF}$ is defined as the common logarithm (base 10) of the soil water suction or tension head expressed in centimeters of a water column: $\text{pF} = \log_{10}(h)$, where $h$ is the hydraulic suction head in $\text{cm}$.
• Calculation: Here, tension head $h = 100\text{ cm}$. Therefore, $\text{pF} = \log_{10}(100) = 2.0$.
• Reference points on $\text{pF}$ scale: Free water / saturation: $\text{pF } 0$ ($1\text{ cm}$); Field capacity: $\text{pF } 2.53$ ($340\text{ cm}$ or $1/3\text{ bar}$); Permanent wilting point: $\text{pF } 4.18$ ($15,000\text{ cm}$ or $15\text{ bars}$); Hygroscopic coefficient: $\text{pF } 4.50$ ($31,000\text{ cm}$ or $31\text{ bars}$); Oven dry: $\text{pF } 7.0$ ($10^7\text{ cm}$).