# Sodium molybdate

> Sodium molybdate dihydrate (Na2MoO4·2H2O), about 39.7% molybdenum, is the common Mo source for micronutrient mixes, used in microgram-per-litre amounts.

- Canonical: https://genetixbay.com/knowledge/glossary/sodium-molybdate.html
- Also written: Na2MoO4, sodium molybdate dihydrate, Na2MoO4·2H2O
- Glossary category: Nutrients · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Sodium molybdate is the soluble salt that supplies [molybdenum](https://genetixbay.com/knowledge/glossary/molybdenum.md) as molybdate. The dihydrate form is about 39.7% Mo and 19% Na. [Ammonium](https://genetixbay.com/knowledge/glossary/ammonium.md) molybdate is a common alternative with a higher Mo content.

## In practice

Molybdenum is needed in the smallest amount of any nutrient, around 0.03-0.05 mg/L (ppm) in the final feed. At that dose the [sodium](https://genetixbay.com/knowledge/glossary/sodium.md) it brings is negligible. It is always dosed from a concentrated [micronutrient](https://genetixbay.com/knowledge/glossary/micronutrient.md) stock, since a single gram would supply enough for several thousand litres. It is one of the few micronutrients that becomes more available as [pH](https://genetixbay.com/knowledge/glossary/ph.md) rises.

## Units and formula

1 mg/L gives about 0.4 mg/L (ppm) Mo. To reach 0.05 ppm Mo, add about 0.13 mg/L.

## Don't confuse with

- **Ammonium molybdate**: another Mo salt, with ammonium instead of sodium.
- **Molybdenum disulfide**: an insoluble lubricant, not a fertiliser.

## Related terms

[Molybdenum](https://genetixbay.com/knowledge/glossary/molybdenum.md), [Micronutrient](https://genetixbay.com/knowledge/glossary/micronutrient.md), [Stock solution](https://genetixbay.com/knowledge/glossary/stock-solution.md), [Sodium](https://genetixbay.com/knowledge/glossary/sodium.md)

## Read more

- [Molybdenum (Mo) in cannabis: the trace element nitrate depends on](https://genetixbay.com/knowledge/nutrients/molybdenum.md)
- [Hydroponic salts explained: what each fertiliser salt supplies](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md)

## Sources

1. Kaiser BN, Gridley KL, Brady JN, Phillips T, Tyerman SD. 2005. The role of molybdenum in agricultural plant production. Annals of Botany 96(5):745-754. https://doi.org/10.1093/aob/mci226
2. Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6