Lime Application Calculator
Calculate agricultural lime needed to raise soil pH.
Please note: Planning figures based on published averages. Soil type, climate, variety, season and local practice all shift these results substantially. Base real decisions on a soil test, local extension guidance and the product label — particularly for fertiliser, lime and any crop protection product, where the label is a legal document.
What the Lime Application Calculator does
Lime requirement depends on how far the pH must move and how strongly the soil resists that move. Clay and organic matter buffer heavily, so a clay soil needs about three times the lime a sandy one does for the same pH change — then the product’s neutralising value adjusts for its purity.
Formula
Pure lime = pH change × Lime per pH unit for the textureProduct rate = Pure lime ÷ Neutralising valueTotal = Product rate × Area
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Current soil pH | number | Yes | Accepts 0 or more, up to 14. |
| Target soil pH | number | Yes | Accepts 0 or more, up to 14. |
| Soil texture | one of 5 options | Yes | — |
| Neutralising value of the lime | % | Yes | Pure calcium carbonate is 100%. Most agricultural lime is 85–95%. |
| Area | number | Yes | Accepts more than 0. |
| Area unit | one of 4 options | Yes | — |
| Lime price per tonne | selected currency | Optional | Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Soil texture and Area unit.
- Enter Current soil pH, Target soil pH, Neutralising value of the lime and Area.
- Optionally add Lime price per tonne.
- Select Calculate.
Worked example
Raising a clay soil from pH 5.5 to 6.5 with lime of 90% neutralising value.
- Current
- 5.5
- Target
- 6.5
- Texture
- Clay
- NV
- 90%
Clay needs 4.5 t/ha per pH unit, so 4.5 t/ha as pure carbonate. At 90% NV that becomes 5 t/ha of product.
Frequently asked questions
How long does lime take to work?
Six to twelve months for a measurable change and up to two years for the full effect. Finer grades react faster but cost more.
What is neutralising value?
The product’s acid-neutralising power relative to pure calcium carbonate. Lime at 90% NV needs applying at about 11% higher rate than pure material.