Vitalize EDU: What Potassium Is (and Isn’t) Doing in Your Soil
Potassium (K) is often abundant in soil, but not always available. Sounds similar to P doesn’t it? Let’s dive in!
Research, including work by Dr. Rick Mulvaney (University of Illinois), shows soils can hold far more K than standard tests indicate. The issue is availability, not just supply.
K can be:
• Tied up in minerals
• Held on the soil colloid
• Temporarily unavailable
pH plays a role.
In acidic soils, K availability can be reduced through interactions with iron and aluminum.
Cover crops help:
•Cycle K into plant-available forms
•Improve soil structure and porosity
•Access nutrients from areas roots couldn’t previously reach
In the plant, K supports:
•Water regulation
•Drought tolerance
•Nutrient and sugar movement
•Overall plant strength
K also plays a role in soil balance on the colloid alongside Ca and Mg.
I like placing K near or at planting to improve early uptake.
But balance matters.
Too much K can:
• Compete with Ca and Mg
• In extreme cases, interfere with other nutrients
Bottom line:
Potassium is critical, but availability and balance matter more than total levels.
