Lime requirement calculator
Lime requirement depends on how far the pH must move and how strongly the soil resists moving — its buffering capacity.
% CaO equivalent
Lime rate
5.000t/ha
- Total lime
- 100.00 tonnes
- Cost
- 3500.00
- Cost per hectare
- 175.00
- Rate per square metre
- 0.500 kg/m2
- pH change required
- 1.00
- Applications to split it into More than about 7 t/ha at once is usually split across seasons.
- 1
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- Current pH = 5.5
- Target pH = 6.5
- Soil type = 5
- Neutralising value of the lime = 50
- Area = 20
- Price per tonne = 35
- pH change required = max(6.5 - 5.5, 0) = 1
- base_rate = 1 * 5 = 5
- Lime rate = 5 * 50 / 50 = 5
- Total lime = 5 * 20 = 100
- Cost = 100 * 35 = 3500
- Cost per hectare = 5 * 35 = 175
- Rate per square metre = 5 / 10 = 0.5
- Applications to split it into = 5 > 7 ? ceil(5 / 7) : 1 = 1
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- rate = pH change x soil buffering factor x 50 / neutralising value
- the 50 normalises to a lime of 50% neutralising value
Buffering factors are rough. A proper lime requirement comes from a buffer pH test, not from pH alone.
Lime is slow. Ground limestone takes one to two seasons to have its full effect.