Recognizing Potassium Deficiencies
Potassium deficiencies can be difficult to diagnose, primarily because they resemble in many aspects, deficiencies in Calcium and Magnesium. There are some distinguishing features however.
How Do I Know It’s A Potassium Problem?
Potassium will typically show up initially as interveinal chlorosis, starting in the older growth. This is because potassium is mobile in the plant, allowing the plant to move what potassium it has from the old growth to the new, delicate growth.
If the potassium deficiency isn’t initially treated, it will get worse, culminating in browning, drying and death of the edges of the leaves, dead, necrotic spots on the leaves, bronzing and cupping.
Each crop can show slightly different symptoms, and oftentimes, when the deficiency becomes extreme, it becomes impossible to differentiate from calcium deficiency.
One tell-tale sign for many crops in aquaponic systems is the stunting of root growth, meaning that plants show slowed or stunted growth and can be easily pulled from the media. The root system of pulled plants will be small, often browned, and lack lots of structure.
To help with diagnosis, please download the key that I’ve developed. It isn’t foolproof, but it can often give you a starting point for diagnosing potassium, calcium, magnesium and iron deficiencies, and help you to see the differences between them.