water-dynamics → infiltration-vs-percolation
Water movement through soil or substrate occurs in two distinct phases:
Confusing these leads to irrigation mistakes, poor root access, and nutrient loss.
Infiltration describes how easily water enters the soil or substrate surface.
It is influenced by: - Surface condition - Particle size distribution - Hydrophobicity - Organic matter - Compaction
Poor infiltration causes: - Runoff - Channeling - Uneven wetting
Percolation describes how water moves downward once inside the profile.
It is influenced by: - Pore size distribution - Structure and layering - Bulk density - Saturation level
Rapid percolation increases: - Leaching - Nutrient loss - Uneven root access
A medium may: - Accept water quickly (good infiltration) - Yet fail to wet evenly
This occurs when: - Preferential flow paths dominate - Fine pores remain dry - Roots sit outside active flow zones
Water movement does not equal water availability.
Water follows the path of least resistance.
Preferential flow: - Bypasses dry zones - Delivers water unevenly - Reduces effective root volume
This explains why roots die back in “wet” substrates.
Roots proliferate where: - Water - Oxygen - Nutrients
coincide.
Poor infiltration or uneven percolation creates: - Patchy root systems - Localised stress - Reduced uptake efficiency
Effective irrigation aims to: - Slow infiltration where needed - Encourage uniform wetting - Avoid excessive percolation - Match application rate to medium properties
Key mistake: - Increasing volume to fix uneven wetting
Water must enter, spread, and remain accessible.