Soil acidity is very important.
Factors which may change soil pH:
- Use of ammonium fertiliers --> More acid soil
- Acid rain --> More acid soil
- Vegetation rotting --> More acid soil
This acidity can be removed by adding crushed limestone (crushed to improve surface area, and therefore rate of reaction)
- Calcium hydroxide and calcium oxide are also used to make soil more basic, however as this is soluble, it will make the soil basic