Sulphur pH Lowering Calculator & Acidify Your Soil
Acidifies for blueberries
Work out the elemental sulphur to lower your soil pH — from current and target pH and your soil texture, the dose in kg/ha, the total, bags and cost.
Enter your soil & target
Next: strongly alkaline — split over seasons — apply ahead of the season, work it into the topsoil, water in, and re-test pH after a few months before adding more.
Complements lime which raises pH; rate ≈ ΔpH × texture factor.
Sulphur & pH — key facts
- Rate
- ΔpH × texture factor
- Sandy
- ≈ 350 kg/ha per pH unit
- Loam
- ≈ 700 kg/ha per pH unit
- Clay
- ≈ 1100 kg/ha per pH unit
- How it works
- microbes → sulphuric acid
- Speed
- weeks to months
- Apply
- ahead of the season, incorporate
- Privacy
- Runs in your browser; nothing uploaded
The acid-soil companion to liming
Lime raises the pH of acid soils; elemental sulphur lowers the pH of alkaline soils — the other half of soil-pH management. Acid-loving crops like blueberries, tea and potatoes need it, and on high-pH soils acidifying frees up iron, manganese and phosphorus that would otherwise be locked away, curing the tell-tale leaf yellowing. The amount needed depends on how far you're shifting the pH and how strongly your soil resists change.
This tool applies texture-specific rates to your current-to-target pH drop to give the sulphur in kg/ha, the total and bags, and the cost. Because soil bacteria do the work, apply and incorporate sulphur well ahead of the season, keep the soil warm and moist, split large requirements over seasons, and re-test before relying on the change. Pair it with the Lime Requirement, Soil Texture and Gypsum tools for full soil-chemistry control.
Acidify accurately
Texture-aware rate, not a one-size guess that under- or over-shoots.
Grow acid-lovers
Hit the pH blueberries, tea and potatoes actually want.
Unlock nutrients
Lower high-pH soils to free iron, manganese and phosphorus.
Budget & bag
Total kg, 50 kg bags and cost for your field.
Frequently Asked Questions
How much sulphur do I need to lower soil pH?+
It depends on how far you're dropping the pH and your soil texture. As a guide, lowering pH by one unit needs roughly 350 kg/ha of elemental sulphur on sandy soil, 700 on loam and 1,100 on clay (clay buffers more). This tool computes the rate, total and bags from your current and target pH.
Why use sulphur to lower pH?+
Many crops — blueberries, tea, potatoes, azaleas and most acid-loving plants — need acidic soil, and alkaline soils lock up iron, manganese and phosphorus. Elemental sulphur is the standard, cost-effective way to acidify soil; this is the mirror image of using lime to raise pH on acid soils.
How does elemental sulphur lower pH?+
Soil bacteria (Thiobacillus) oxidise the sulphur to sulphuric acid, which lowers pH. Because it's a biological process, it's gradual — taking weeks to months and needing warm, moist, aerated soil. That's why you apply sulphur well ahead of the crop, not the day you sow.
Why does soil texture matter?+
Clay and high-organic soils resist pH change (high buffering), so they need much more sulphur than sandy soils for the same drop. The tool uses a texture-specific factor — sandy needs the least, clay the most — so the rate suits your soil rather than a one-size-fits-all number.
How long does sulphur take to work?+
Typically a few weeks to several months, depending on soil temperature, moisture, sulphur particle size (finer is faster) and the microbial population. Apply and incorporate it well before planting, keep the soil warm and moist, and re-test pH before relying on the change.
Can I add too much sulphur?+
Yes — over-acidifying can drop pH below the crop's range, harm soil life and free up toxic levels of aluminium or manganese. Aim for the crop's target pH, split large requirements over seasons, and re-test rather than dumping a big dose at once. The tool flags strongly alkaline soils for staged treatment.
What's the difference between sulphur and gypsum?+
Elemental sulphur lowers pH (acidifies); gypsum (calcium sulphate) does NOT change pH — it reclaims sodic soils by supplying calcium to displace sodium. Don't use gypsum to acidify, or sulphur to reclaim sodic soil. Use the Gypsum tool for sodic soils and this tool to lower pH.
How do I apply elemental sulphur?+
Broadcast the finely-ground sulphur evenly and incorporate it into the topsoil where the microbes live, ahead of the season. For established acid-loving plants, work it lightly into the surface and mulch. Keep the soil moist so the oxidising bacteria stay active.
Will lowering pH free up nutrients?+
Often yes — in alkaline soils, iron, manganese, zinc and phosphorus become more available as pH falls toward neutral/slightly acidic, curing the yellowing (chlorosis) common on high-pH soils. Aim for the pH range your specific crop prefers rather than the lowest possible.
How often should I re-test and re-apply?+
Re-test pH after each season or a few months after applying. Soils naturally drift back toward their parent pH over time (especially calcareous soils), so periodic top-up applications may be needed. Re-run this tool with the new current pH to size the next dose.