pH Solo: Calcário/Enxofre

Soil pH correction with lime and sulfur

Most crops do best in soil pH somewhere between 6.0 and 6.8, slightly acidic to neutral. When you need to raise the pH and correct acidity, reach for dolomitic lime; on medium-texture soil, around 2–3 t/ha moves the pH up by a full unit. Going the other way, to lower pH on alkaline soil or for acid-loving plants like blueberries, use elemental sulfur, where roughly 0.5 t/ha drops the pH by a unit. The catch is that the reaction is slow and takes 6–12 months to fully kick in, so get it down before the planting season. As an example, a hectare moving from pH 5.5 to 6.5 calls for about 2.5 t of dolomitic lime.

Applications

This comes up in agriculture, gardening, nursery work and pasture restoration. Before any liming, EMBRAPA recommends running a soil analysis first, since the right dose hinges on V% (base saturation), CEC and clay content. A generic calculator gives you a starting estimate, nothing more than that; it won't replace a soil-specific prescription.

FAQ

Lime or gypsum? They do different jobs. Lime corrects pH at the surface, while agricultural gypsum (calcium sulfate) leaves pH untouched but feeds Ca into the subsoil so roots can push deeper.

Why does it take so long? Lime won't react without moisture, so a stretch of dry months will stall the correction. Work it into the top 20 cm and irrigate where you can.

Can I overdose? You can. Over-liming pushes the pH past 7 and locks up micronutrients (Fe, Mn, Zn), so stick to what the soil analysis recommends.