Vitalize EDU: What Magnesium Is (and Isn’t) Doing in Your Soil
Magnesium (Mg) is often overlooked, but it plays a critical role in both soil and plant function.
Like calcium, magnesium sits on the soil colloid.
It’s part of base saturation alongside:
- Calcium (Ca)
- Potassium (K)
Balance between these drives how your soil behaves.
Magnesium influences soil structure, but differently than calcium.
- Calcium helps loosen and aggregate soil
- Magnesium tends to create denser, tighter soil structure compared to calcium
Too much Mg can:
- Reduce porosity
- Slow water infiltration
- Create heavier, tighter soils
But too little Mg isn’t good either.
In the plant, magnesium is essential for:
- Photosynthesis (chlorophyll production)
- Energy transfer
- Enzyme activation
Energy transfer is how the plant captures and uses energy to grow, and magnesium is central to that process.
No magnesium = reduced photosynthesis and plant energy.
This is where understanding CEC matters.
CEC helps define how nutrients like Ca, Mg, and K are held and balanced on the soil colloid.
Targets should align with your goals:
- Tillage vs. no-till
- Irrigated vs. non-irrigated
- Soil type and structure
Back to balance.
Magnesium is antagonistic with:
- Calcium (Ca)
- Potassium (K)
Too much Mg can limit Ca uptake and tighten soils.
Too little Mg can limit plant function.
This even applies to foliars.
Magnesium is mobile in the plant, so foliar applications can help correct deficiencies more systemically.
Calcium is not, so consistent root uptake is critical, with foliar Ca being more situational.
That’s why we don’t chase magnesium or calcium blindly.
I often hear, “I just apply gypsum, it’s great.”
But without understanding your base saturation, you could be reducing magnesium availability and impacting photosynthesis efficiency in the plant.
We look at:
- Base saturation
- CEC and soil type
- Plant response
Understanding this, along with the previous posts, helps bring soil chemistry into balance, leading to better lime decisions, smarter foliar choices, and improved results, whether that’s yield or forage quality for wildlife.
