Home › MCQs › Agronomy › Question #2056
Back to Questions
Agronomy QUESTION #2056
Question 1
The plant-available water capacity (PAWC) of a soil is correctly expressed as:
  • The moisture content at field capacity only
  • \(PAWC = \theta_{FC} - \theta_{PWP}\), where \(\theta_{FC}\) is volumetric water content at field capacity (\(-33\) kPa) and \(\theta_{PWP}\) is at permanent wilting point (\(-1500\) kPa)✔️
  • The total porosity of the soil minus bulk density
  • The gravitational water fraction that drains within 48 hours of saturation
Correct Answer Explanation
PAWC represents the reservoir of water accessible to plant roots. It equals the difference in volumetric water content between field capacity (−33 kPa, where drainage becomes negligible) and permanent wilting point (−1500 kPa, where plants cannot extract water). Sandy soils have low PAWC; loam soils have the highest.