Fertilisers include about twenty chemicals required for healthy plant growth and fertiliser companies also supplied other materials such as lime for treating acidic soils.
Early fertilizers were all organic; farmyard manure, composts, bone meal, blood, seaweed meal, and fishmeal. The railways were involved in shipping natural manure from the 1840's, there was rather a lot of this to shift as horses provided most of the power and human manure, collected by local councils and sold as 'night soil', was also a regular cargo. Cheap rail-hauled coal meant that lime could be made much more cheaply and other materials such as wool and cotton waste (called shoddy) was shipped from the Northern mill towns to be ploughed into the land.
Probably the single most important fertiliser was Ammonium Sulphate, originally supplied in the form of bird droppings or 'guano' (mostly recovered from large deposits found on islands off the Chilean and Peruvian coasts and from Ocean Island in the Indian Ocean). The three most important fertilisers are nitrogen, phosphorous and potassium and guano contains all three (about 10% nitrogen with about 60% phosphorous and 2% potassium). This material is white and powdery and arrived in the country in bulk, being shipped by rail having been bagged in hessian sacks.
Artificial fertiliser (as opposed to manure) dates from the manufacture of superphosphates in 1842 by L. B. Lawes. The naturally occuring Chilean sodium nitrate beds were exploited from about the 1870's until the development of synthetic ammonia using the Haber process (discussed under Chemicals) in about 1900.
Ammonia contains Nitrogen and so forms the basis for many of the more important fertilisers. Guano was augmented by ammonium phosphate made at the town gas works and around the First World War the Germans devised a way of synthesising ammonia directly using nitrogen from the air. This manufactured ammonia killed off the trade in guano from Chili although imports from Ocean Island continued into the 1970s. By the end of the Second World War the UK was going through a million tons of fertiliser made from synthetic ammonia and a further quarter of a million tons based on the ammonium sulphate from gas works and coke plants.
Simple phosphate fertilisers are made from pulverised bones (animal and fish bones have both been used) or phosphate rock, a naturally occurring light grey mineral imported from America, Russia and North Africa in the form of rubble. The 'knackers yard' was originally where old horses were sent to be killed and processed, other dead animals often ended up there including cats and dogs and butchers sent the bones left from their trade. The recovered meat was sold off and the bones were then boiled off to remove the fat (which was sold off, some going into margarine). Some of the bones were used to make glue and the rest were powdered to produce 'bone meal', a white powder sold as fertiliser in bags.
Super Phosphate is made by treating pulverised phosphate rock with sulphuric acid to produce a solid form of phosphoric acid (see under Chemicals, salt and plastics industries). Super phosphate was a crystaline material and was often shipped in jute bags although the fumes tended to rot through the bags if stored for any length of time. Super phosphate is a very important fertiliser, over a million tons a year was being shipped in the UK by the 1950's, mostly by rail. The factories making this often made their own sulphuric acid, using mainly using imported sulphur but saller establishments would buy in the acid, which might be delivered in rail tanks.
Potassium is usually supplied to the land in the form of potash, (potassium carbonate). The ash left after wood is burnt contains about 4% potash, which is why farmers burn off the stubble after harvesting. Since the Second World War a lot of potash has been supplied from the Dead Sea via the Israli port of Haifa, this is a little different in that it is potassium chloride rather than carbonate, but the potassium is the valuable part of the mix. Fertilisers account for most of the consumption of potash although quantities were and are also used in glass manufacture, soaps and for preparing leather.
Limestone, and other forms of calcium carbonate such as crushed sea shells and the waste from paper mills and sugar beet factories, is used to reduce soil acidity. Another source of this material was 'basic slag' from steel works which also contains a lot of phosphate. Producing a ton of steel uses about half a ton of limestone, this does not form part of the finished steel but is left behind as part of the 'slag' or waste. Basic slag contains variable amounts of tricalcium phosphate, calcium silicate, lime and oxides of iron, the phosphorous and lime are the useful fertilisers in the mix. The slag was purchased by the fertiliser companies, crushed, bagged and sold to farmers as a black powder which stained the unloading areas in the goods yards when it arrived.
From the above it is apparent that fertiliser factories are really large chemical works. They feature tanks of various kinds, buildings for storing powders and granular material, quite a few chimneys and piles of material laying in the open. In many way they resemble an oil refinery, although they do not have the tall 'fractionating colum' towers.
By the 1950's bulk ammonia gas from oil refineries was becoming available and several fertiliser factories adopted spherical pressurised tanks similar to those seen in oil refineries to hold the ammonia under pressure and keep it liquid. These tanks wre in use prior to World War Two but I have not (yet) seen any reference to them in British fertiliser works prior to about 1950. See 'Lineside Industries - Prototype industrial ancillary structures' for more information.
More recently something called 'animal tankage' has appeared, this is made from the unused parts of animals recovered from abattoirs. This material is boiled under pressure and allowed to settle. The oils and fat are then skimmed off the top, and what is left is drained and filtered. These solids are pressed and dried to be sold as fertiliser, they contain ammonia and bone phosphate, typically 10% and 20% respectively.
When modelling a fertiliser works (any period from the 1840's on) you do need to bear in mind the changes in the industry, for example there was a Peruvian Guano Works in London's docks in the 1880's but guano would have been phased out in the early twentieth century with the development of the Haber Process. Not all fertiliser firms had fertiliser in their name, Odams Chemical Manure Co was established in 1852 and produced nitrates and phosphates.
The British fertiliser industry was pretty well dominated by Fisons (formed by amalgamation 1842) until 1982 when they sold the fertiliser side of the business to Norsk Hydro who operate it today. ICI fertilisers set up a plant at Billingham in 1926 and the oil giant Shell established a works at Ince close by Stanlow refinery in 1969 (this is the company, trading as UKF, which operated the fleet of large curtain sided vans, subsequently modified to door-sided as illustrated below). They were taken over in (I believe) 1990 by Kemira, but rail transport ended in 1993.
Fig ___ UKF/Kemira bogie van and UKF ammonia tanker
Three quarters of the fertiliser produced is used by about one quarter of the world's population. Holland gets through as much as all of South America and India's 500 million use only as much as Sweden's 7.5 million. At the present rate of production the weight of one years fertiliser should exceed the weight of all of humanity by the year 2000.
At the receiving end the fertilizer may be spread on the land during the winter or shortly before seeding time. These days (since the later 1970's) commercial fertilizers are commonly placed in the soil, along with seeds, by drills and planters. Manure and other consolidated fertilizers are applied most efficiently by a muck spreader, which is a wagon equipped with a bottom conveyor to carry the fertilizer back to a beater attachment, which disintegrates it and then scatters it on the ground. These only appeared in the 1950's however and before that the standard method was to haul a cart across the field and spread the stuff with forks.
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