Liming and Ca/Mg ratio
Correcting pH is not enough. It is the Ca/Mg balance that unlocks the true potential of the soil.
Many think that liming = raising the pH, but that is only the visible part of the iceberg.
In the majority of acidic soils, it is the cationic balance that must be targeted
🎯 68% calcium and 12% magnesium on the CEC of a Kinsey/Albrecht soil analysis.
Why? Because this ratio:
🧱 structures the soil (crumbly, aerated, rootable)
🌿 facilitates the assimilation of nutrients and the efficiency of nitrogen
🔄 boosts microbial life
👉 Too much Ca = soil too aerated, drying, leachable, lacks internal cohesion
👉 Not enough Ca = impacted microbiology and poor structure
👉 Too much Mg = sticky, suffocating soil
👉 Not enough Mg = deficiencies, stagnation, yield drop
⚠️ The trap of “all-limestone”… which worsens Mg deficiency
The reflex “I add CaCO₃ and everything will be fine” is persistent… and sometimes counterproductive.
Without magnesium input:
- pH rises, but Mg decreases on the CEC
- The plant lacks Mg without it being immediately visible
Result: 🌾 yellowing, weak tillering, slowed photosynthesis
💸 Magnesium deficiency: the bill is discreet… but steep
Even without visible symptoms, yield losses often hover around 10–15%.
- 🌾 Wheat: –7 q/ha = ~140–210 €/ha
- 🌽 Corn: –9 to 10 q/ha = ~160–180 €/ha
- 🌻 Rapeseed: –4 to 5 q/ha = ~90–110 €/ha
- 🍇 Vine: –10% = ~250 €/ha (not counting quality)
Cumulatively, a lack of Mg can cost 150 to 250 €/ha.
✅ Which amendments to choose?
- Acidic + low in Mg
👉 Dolomite and/or magnesium lime
- Acidic + sufficient Mg
👉 limestone alone (CaCO₃)
💡 If you have trouble finding dolomite, a mixture of limestone and kieserite is also very effective but a bit more expensive.
At what dose?
All recommendations appear on your soil analysis report and are calculated to the nearest kg taking into account your amendment history and your actual CEC.
What about gypsum?
⚠️ Gypsum (CaSO₄) provides sulfur and Ca, but does not raise pH and can leach Mg. It is a complement… not a substitute.
