In the previous article we explored what happens when calcium loses its place on the exchange complex. Structure begins to weaken. Soil architecture becomes vulnerable.

Often the mineral that steps forward when calcium steps back is magnesium.

Magnesium is an essential nutrient. It anchors chlorophyll. It participates in photosynthesis.

But when magnesium becomes dominant on the exchange complex, the physical character of soil begins to change.

What was once open and crumbly can begin to feel tight.

Magnesium's Place in Soil

Magnesium is one of the base cations held on the exchange complex along with calcium, potassium, sodium, and hydrogen.

In balanced soils, magnesium occupies a moderate portion of exchange sites—enough to support plant nutrition without shaping the soil’s physical structure.

When magnesium begins to dominate relative to calcium, its influence becomes structural rather than simply nutritional.

Magnesium ions are smaller and pull soil particles closer together.

The...