26 Sept 2022

Then & Now: Kilns that fired Irish farming

Then & Now: Kilns that fired Irish farming

With the price of fertiliser these days, we might just have to bring back the old lime kilns

THE PRICE of fertiliser has dramatically increased in price this year and many farmers have cut back their annual amount to spread on their pastures as a result. Before fertiliser was introduced into Ireland the farmers used their own manure from the animals that were housed over the winter months.
A dung (manure) heap could be seen outside the majority of houses, which was then spread on the pastures and meadows each spring, to produce grass and hay for the coming year. Over the years this manure has been turned into slurry which is applied at certain times to boost crops.
All over the country farmers would also spread lime on their pastures to neutralize the soil that had become too rich in acid.
“Burnt” lime would have been used primarily on the land to break up the heavy clay soil and ‘sweeten’ the grass. The making of lime was quite common and a local event in most areas for many years. From what I have heard and read the making or “burning” of lime was almost as common as sowing the crops. Of course, there was no merchant that commercially supplied lime so making one's own was essential. Too much lime could lead to the soil becoming soggy, so a balance was needed. The lime was produced from crushed limestone that was burned in a kiln. The limestone would have to be drawn by horse and cart long distances from limestone areas to its destination. When the load arrived, the stone had to be broken down into small lumps to make it more suitable for burning.
Lime kilns were a common feature of rural landscapes throughout Ireland. Not every farm had a lime kiln but almost every town land could boast of having at least a few, and neighbours shared theirs with each other. Lime spread on the land gave great crops of hay, and fine gardens of potatoes and vegetables. People always shook lime on the potato ridges to prevent the black slug which was a constant pest burrowing into the main crop of potatoes. Lime kilns were chimney like structures in many cases or they were often built into the side of a mound or hill. Rocks of limestone was heated to a high temperature to produce lime. The process was known as “burning the lime.”
The most common type of lime kiln consisted of a bricked lined chamber with an opening at the bottom of the chamber for allowing air into the fire, lighting the fire itself and, of course, removing the lime. It was usually constructed of locally available material. Most often stones were used in its construction and the stones were of varying sizes with small stones also being used for filling and sealing.
The stones were bonded with the “daub” or Lime, gypsum, iron, and other mineral mixture that is carried up to the surface of soil by capillary action and deposited to form a natural concrete and was probably a clay bond originally.
The lime-kiln itself was a square stone building, 16 to 20 feet high and about the same width. It had an open top approached by a ramp to enable the loads of limestone to be dropped in. The inside of the kiln was egg-shaped and it operated by gravity almost like the modern solid-fuel cooker. One wall had an arched opening at the bottom to allow the lime-burner to take out the lime. Above the opening was the floor of the kiln made of spaced iron bars to allow the lime to fall through.
Coal and wood usually provided the fuel to burn the limestone, but it has been known for turf to be used also. The process began with the stones been broken into pieces about the size of a man’s fist using a sledge hammer before they were transported to the site by horse and cart. Alternative layers of fuel and stone were placed in the kiln until it was filled to the top. The fuel was ignited at the bottom of the kiln and the burning process allowed to proceed. A minimum temperature of about 900°C was required to convert the limestone to lime until the limestone reached a bright red glow. The burning took around four days. It was easy to separate the ashes from the lime after burning, the former being of a lighter substance would always blow away when shoveled from the kiln.
Besides using the lime on the land which was probably the primary purpose the lime was also used for many other purposes and in many other ways. It was mixed with sand to make a lime mortar for building purposes, and in whitewashing the walls of houses and it also had the effect of making the walls waterproof. Making whitewash was a simple process, simply mix the lime and water. Some people used to add a “ball” of Ricketts ”blue” to make the wash even whiter and sometimes even two or three were added. I assume that is the reason when you see some old, thatched houses around the countryside today that you see a cast of blue on the white walls.
Springtime or summer were the usual times for whitewashing the house and out-houses and a fine day was always chosen. The whitewash was applied by brush which was often made from heather, straw, rushes or horsehair. It was also used as a “paint” inside the old houses, particularly the old, thatched homes. All the furniture and crockery were moved outside if the inside of the house was being done.
Lime was also a good disinfectant on the inside of houses, sheds and hen houses. It was also used as a snail and slug repellent, used to kill ants and cockroaches, used to disinfect cesspit’s and outdoor lavatories, used to disinfect spring wells, used to prevent foot rot in livestock, given as a worm drench for pigs, spread on the drills as a rooting powder for cabbage plants, diluted in water and sprinkled to deter disease on fruit trees and was given to poultry that were producing eggs to strengthen the egg-shells.
By the middle of the 20th century, limekilns had gone out of use because of the bulk availability of lime through hardware and agricultural stores. This had the same agricultural effects as the burnt lime and was much cheaper to produce and was delivered on site by CIE lorries. The remains of old abandoned lime kilns can still be seen around the countryside as relics of olden times.

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