water-dynamics → preferential-flow
Water does not move evenly through soil or substrates.
It follows preferential flow paths — routes of least resistance that bypass much of the root zone.
Preferential flow explains why roots suffer stress in systems that appear well irrigated.
Preferential flow occurs when water:
This results in uneven wetting and uneven nutrient distribution.
Preferential flow develops due to:
Once established, it tends to persist.
Surface wetness often looks uniform.
Below the surface: - Water may move vertically in narrow channels - Large areas remain dry - Roots are excluded from active zones
This disconnect leads to misdiagnosis.
Preferential flow causes:
Roots outside flow paths experience drought even in wet systems.
Nutrients move with water.
Preferential flow causes: - Localised high EC in channels - Nutrient leaching beyond roots - Inefficient fertiliser use - Variable plant response
This explains inconsistent tissue analysis results.
Reducing preferential flow focuses on:
Key mistake: - Increasing volume to compensate for uneven response
Uniform irrigation does not guarantee uniform wetting.