Maximum hygroscopicity
The maximum amount of moisture a dry soil can absorb from the atmosphere under saturation conditions, expressed as a percentage of the soil's dry weight.
Также говорят: total hygroscopicity, adsorption water capacity
Maximum hygroscopicity is primarily determined by the soil texture and the amount of organic matter present. Soils rich in clay minerals and humus exhibit higher values due to their extensive surface area capable of adsorbing water vapor.
Agronomists use this parameter to characterize the physical state of the soil and to distinguish between different soil types. It serves as a critical indicator for understanding how soil moisture dynamics behave under varying atmospheric humidity levels.
A common mistake is failing to account for the fact that water held at the level of maximum hygroscopicity is unavailable to plants. Because it is bound by strong molecular forces, this moisture does not contribute to plant growth and should not be included in calculations of plant-available water.