Limestone in Agriculture

The use of lime on the land as an aid to crop growth is an ancient feature of good farming practice. In fact the liming of agricultural land was known and appreciated long before the most active days of the pioneer agrarian improvers.
In recent times (post Second World War) the majority of the lime produced from Wenlock quarries for use in agriculture has been ground limestone containing more than 86% of calcium carbonate.

Pot Kiln adit. Ballstone Quarry

Pot Kiln adit. Ballstone Quarry [+]
Pot Kiln adit at Ballstone Quarry or Lower Spittlefield near Much Wenlock

Originally, all the lime for soil fertilisation was burnt lime, and it appears that when limestone was burnt for mortar the less pure lime was sold as fertiliser. Particularly this was so before the use of coal or coke in the kiln when timber was the fuel used and great quantities were required resulting in a great deal of ash in the lime to reach the temperature needed for calcination to take place.

Diagram of a running limekiln

Diagram (not to scale) of a limekiln [+]
This is a diagram of a running kiln often up to 100 tons in capacity. As lime is withdrawn through the grate, so additional limestone is added into the top of the kiln.

Lime (burnt, hydrated or ground) is used to combat acidity in soils. Soils become acid, particularly light sandy soils and soils of high elevation if the lime content is low. For example, barley, sugar beet and lucerne will not prosper in acid soils.

Soils will gradually lose lime by leaching, cropping, feeding livestock (dairy cows can take up to 80kg of lime per annum) and manuring, i.e. by continued application of sulphate of ammonia.