Potassium Nitrate (13-0-46) Calculator & Dosage Guide

Potassium Nitrate (KNO3) is a highly soluble fertilizer providing dual macronutrients (Nitrogen & Potassium), essential for fruit sizing, bloom quality, and disease resistance.

Nitrogen13N
Phosphate0P₂O₅
Potash46K₂O
Solubility:316 g/L
Standard Temp:20°C

Pre-configured Potassium Nitrate Calculator

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Calculated Recipe Output

Configure your targets and click "Run Analysis" to generate your fertilizer recipe.

1. What is Potassium Nitrate?

Potassium Nitrate is a high-grade chemical source supplying essential plant nutrients. The standard NPK ratio of this fertilizer is 13-0-46, which signifies that it contains 13% Nitrogen (N), 0% Phosphorus as P₂O₅, and 46% Potassium as K₂O by total product weight. Under agronomic standards, the phosphorus and potassium components are expressed in their oxide forms rather than elemental phosphorus and potassium.

When dissolved in water, this fertilizer dissociates into plant-available ionic nutrients. This allows roots to absorb them instantly via active transport. Understanding the exact composition prevents chemical lockouts and guarantees optimal nutrient concentrations.

2. Best Used For

This fertilizer is highly effective when applied to crops and systems requiring quick, specific nutrient supply:

  • Hydroponic Tomato
  • Pepper
  • Potato
  • Strawberry
  • Sugarcane

3. Solubility & Mixing Instructions

At a standard temperature of 20°C, the maximum solubility limit of Potassium Nitrate is 316 grams per liter of water. Attempting to mix at concentrations above this threshold will result in precipitation, leaving undissolved particles at the bottom of your reservoir or mixing tank.

Step-by-Step Dissolution Method

  1. Fill your clean mixing vessel or reservoir with 70% of the total target water volume.
  2. Using a digital scale with at least 0.1g precision, weigh out the required amount of Potassium Nitrate calculated above.
  3. Gradually pour the dry fertilizer granules into the water while continuously agitating or stirring.
  4. Stir until the crystals are completely dissolved, then top off the vessel with water to reach the final 100L volume.
  5. Measure the Electrical Conductivity (EC) or Total Dissolved Solids (TDS) using a calibrated meter to verify target ppm.

4. Chemical Compatibility & Warnings

To prevent chemical reactions that render nutrients unavailable to plants, observe the following compatibility constraints:

Highly soluble, but solution cools significantly when dissolved. Warm water helps speed up the process.

Avoid mixing with high concentrations of phosphate in hard water to prevent cloudiness.

5. Related Fertilizers

Compare or blend Potassium Nitrate with other high-grade fertilizer materials to complete your custom recipe: