Marsden Quarry produces two types of agricultural limestone as defined by the Fertiliser Regulations 1991:
- Ground Limestone, consisting largely of calcium carbonate and known as Calcium Lime
- Magnesian Ground Limestone, consisting largely of calcium carbonate and magnesium carbonate and known as Magnesium Lime
Agricultural limestone is used primarily to maintain soil at the correct acidity (pH). It also improves soil structure, increases plant nutrient uptake and increases bacterial activity in the soil. Soil that has become too acidic due to fertilising, cropping, leaching and to a lesser extent as a result of acid rain, can be treated with limestone to correct the acidity and restore yields. The application of lime onto the soil via a spreader is a cost effective way of maintaining correct soil pH on both arable and grassland.
Other benefits of agricultural lime are the input of trace elements, the increased effectiveness of agrochemicals and in the case of Magnesium Lime, the provision of a boost to the production of chlorophyll, and to help prevent hypomagnesaemia in cattle and sheep.
There are four determinants of the effectiveness of agricultural lime:
- Neutralising Value
- Reactivity (Speed of reaction)
- Hardness of the parent rock
Marsden Lime benefits from both a high neutralising value and reactivity and far exceeds the requirements of the Fertilizer Regulations with regard to fineness.