# Nitrate

> Nitrate (NO3-) is the main form of nitrogen in hydroponic and soilless feeds; its uptake tends to push root-zone pH upward.

- Canonical: https://genetixbay.com/knowledge/glossary/nitrate.html
- Also written: NO3-, NO3, nitrate nitrogen, NO3-N
- 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"

Nitrate is the negatively charged ion NO3-, the dominant nitrogen form in mineral feeds and in aerated soil. Roots absorb it actively, store it in vacuoles and reduce it to [ammonium](https://genetixbay.com/knowledge/glossary/ammonium.md) inside the plant before building amino acids, a step that needs [molybdenum](https://genetixbay.com/knowledge/glossary/molybdenum.md).

## In practice

Most cannabis feeds supply 80-100% of their nitrogen as nitrate, from [calcium nitrate](https://genetixbay.com/knowledge/glossary/calcium-nitrate.md), [potassium nitrate](https://genetixbay.com/knowledge/glossary/potassium-nitrate.md) and [magnesium nitrate](https://genetixbay.com/knowledge/glossary/magnesium-nitrate.md). When roots take up nitrate they release hydroxide or bicarbonate to stay balanced, so a nitrate-heavy [recirculating](https://genetixbay.com/knowledge/glossary/recirculating-system.md) reservoir drifts up in [pH](https://genetixbay.com/knowledge/glossary/ph.md) over days. Growers counter that with a small ammonium fraction or acid.

## Units and formula

Labels and [lab reports](https://genetixbay.com/knowledge/glossary/coa.md) may quote "nitrate" or "NO3-N". NO3-N counts only the nitrogen: 1 mg/L NO3-N = 4.43 mg/L NO3-. Always check which one a report means.

## Don't confuse with

- **Nitrite (NO2-)**: an intermediate, toxic at higher levels, not a feed form.
- **Ammonium**: the positively charged nitrogen form, which pushes pH down.
- **Nitrogen**: the element, counted the same whichever ion carries it.

## Related terms

[Nitrogen](https://genetixbay.com/knowledge/glossary/nitrogen.md), [Ammonium](https://genetixbay.com/knowledge/glossary/ammonium.md), [Calcium nitrate](https://genetixbay.com/knowledge/glossary/calcium-nitrate.md), [Potassium nitrate](https://genetixbay.com/knowledge/glossary/potassium-nitrate.md), [Nitric acid](https://genetixbay.com/knowledge/glossary/nitric-acid.md)

## Read more

- [Nitrogen (N) in cannabis: nitrate vs ammonium, deficiency, toxicity and targets](https://genetixbay.com/knowledge/nutrients/nitrogen.md)
- [pH drift in hydro: why reservoir pH rises (and sometimes falls)](https://genetixbay.com/knowledge/ph-ec/ph-drift-hydro.md)

## Sources

1. Saloner A, Bernstein N. 2022. Nitrogen source matters: high NH4/NO3 ratio reduces cannabinoids, terpenoids, and yield in medical cannabis. Frontiers in Plant Science 13:830224. https://doi.org/10.3389/fpls.2022.830224
2. Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9