Nutrition & Root-Zone Chemistry
EC, Salinity & Osmotic Stress
Electrical conductivity estimates the ionic strength of a solution but does not identify which ions are present. High root-zone salinity can reduce the plant's ability to take up water even when the medium is physically wet.
Key concepts
- EC is a bulk conductivity measurement, not a nutrient recipe
- Higher dissolved-salt concentration lowers water potential
- Salinity can interact with heat and atmospheric demand
- Different ion mixtures can produce similar EC values
What to measure or observe
- Track input and representative root-zone EC
- Record irrigation volume and drainage behavior
- Observe wilt or tip/margin injury in context
- Check source-water contribution to EC
Common mistakes
- Treating EC as a direct measure of nutrient balance
- Responding to high EC by adding more fertilizer
- Ignoring uneven salt accumulation
- Assuming wet media means water is equally available to roots
Visuals this lesson still needs
- EC versus ion identity graphic
- Osmotic water-potential diagram
- Salt-accumulation profile
- Salinity stress differential