Liming in Scotland
Lime is a chemical compound used widely in both construction and agriculture.
The uses of lime
In building, it was used in cement and mortar and lime-wash was used to waterproof walls.
In farming, the calcium-based compound neutralises acids in the soil, sweetening it for crops. In addition, calcium is an important nutrient for plants.
Calcining is the chemical process that turns limestone (calcium carbonate) into quicklime (calcium oxide), traditionally achieved by heating it in a stone-built kiln. There is a limekiln at Dunardry in Knapdale Forest.
This is a picture of the lime kiln at Dunardry.
The lime removed from the kiln was in lumps, sometimes called lime shells because of their size and shape. To spread across the soil, it needed to be in powder form.
The next process was slaking. This involved adding water to the lime. It immediately reacted and began to crumble. Often farmers undertook this process while transporting it by cart to the fields. This was dangerous. The violent reaction between the water and lime creates heat that could set carts on fire.
Alternatively, the lime was left in little piles in fields to allow the elements to complete the slaking process and then ploughed into the soil. This final process is known as liming. Based on information from Limekilns and Limeburning by Richard Williams (2004).