# Ammonium nitrate

> Ammonium nitrate (NH4NO3) is a 34-35% nitrogen salt, half ammonium and half nitrate, used in small amounts to steer root-zone pH in hydro.

- Canonical: https://genetixbay.com/knowledge/glossary/ammonium-nitrate.html
- Also written: NH4NO3, 34-0-0
- Glossary category: Nutrients · Evidence: Supported
- 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"

Ammonium nitrate is a salt containing nitrogen in both its main plant-available forms: about 17% as [ammonium](https://genetixbay.com/knowledge/glossary/ammonium.md) and 17% as [nitrate](https://genetixbay.com/knowledge/glossary/nitrate.md), for 34-35% total N. It is very soluble and strongly hygroscopic.

## In practice

In mineral hydro it is used sparingly to add an ammonium fraction, which offsets the [pH](https://genetixbay.com/knowledge/glossary/ph.md) rise caused by nitrate uptake. Langenfeld and Bugbee examined [nitric acid](https://genetixbay.com/knowledge/glossary/nitric-acid.md) and ammonium nitrate as tools for pH control in [recirculating systems](https://genetixbay.com/knowledge/glossary/recirculating-system.md). Too much shifts the NH4/NO3 balance and harms cannabis yield and quality. Pure ammonium nitrate is restricted or regulated in many places because it is an oxidiser with explosive potential; many growers use calcium ammonium nitrate or the ammonium in fertiliser-grade [calcium nitrate](https://genetixbay.com/knowledge/glossary/calcium-nitrate.md) instead. Check local rules.

## Units and formula

1 g/L gives about 340-350 mg/L (ppm) N, half as NH4-N and half as NO3-N.

## Don't confuse with

- **Calcium ammonium nitrate (CAN)**: ammonium nitrate blended with limestone or dolomite.
- **Ammonium sulfate**: ammonium with [sulfate](https://genetixbay.com/knowledge/glossary/sulfate.md), more acidifying.
- **Urea**: an organic N compound needing enzymatic conversion.

## Related terms

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

## Read more

- [Hydroponic salts explained: what each fertiliser salt supplies](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md)
- [pH drift in hydro: why reservoir pH rises (and sometimes falls)](https://genetixbay.com/knowledge/ph-ec/ph-drift-hydro.md)

## Sources

1. Langenfeld NJ, Bugbee B. 2025. pH control in recirculating hydroponics with nitric acid and ammonium nitrate. HortScience 60(9):1555. https://journals.ashs.org/view/journals/hortsci/60/9/article-p1555.xml
2. 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