Fertilizer Concentrates and Compatibility

Some fertilizer materials interact to form insoluble compounds and precipitates when mixed together in a single concentrated solution. These precipitates fall out of solution, tying up nutrients and making them unavailable to the plant — and potentially clogging irrigation systems.

For example, fertilizers containing calcium must never be mixed with fertilizers containing sulfates or phosphates in the same concentrated stock tank:

Ca(NO₃)₂ + K₂SO₄ → CaSO₄ ↓ (precipitate)
Calcium Nitrate + Potassium Sulfate = Calcium Sulfate (gypsum) precipitate

Fertilizer Compatibility Charts

The charts below show which fertilizer combinations are compatible, conditionally compatible, or incompatible in concentrated stock solutions.

Nutrient Solutions for Greenhouse Crops — Free PDF Guide

For a comprehensive look at making fertilizer stock solutions, download this industry reference manual:

Nutrient Solutions for Greenhouse Crops
Edited by Geerten van der Lugt

Produced in collaboration by Yara, SQM, AkzoNobel, Eurofins Agro, NMI Research Institute, and consultant Geerten van der Lugt, this manual provides growers worldwide with up-to-date information on the correct use of nutrient solutions in horticulture. It covers the principles of fertigation, preparation of nutrient solutions, and includes recipes for various horticultural crops grown in soil, organic material, or inert substrates. All nutrient solutions in the manual can be prepared using fertilizers available from Custom Hydro.

Questions about mixing your stock solutions or fertilizer compatibility? Contact us — we’re happy to help you build a safe, effective program.