This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This is principally composed of carbon, and is not only valuable as a manure, but also as a preventive against attacks of slugs, snails, caterpillars, etc. One ton of soot contains about 90 lb. nitrogen, 25 lb. phosphates, 25 lb. potash, and 200 lb. carbonate of lime. It is therefore an excellent all-round manure, and after it has been exposed to the air for six or eight weeks may be safely used for almost any vegetable or flower crop in the open air. From 30 to 50 bus. per acre is a fair dressing. Soot is highly valued as the basis of a liquid manure by gardeners who grow large numbers of plants in pots. About 1 pk. to 30 gal. of water will yield a useful liquid manure. It is better to put the soot into a bag and sink it in a tub of water, as the loose soot does not mix freely with the water. Owing to its chemical composition it is a much better and safer liquid manure than sulphate of ammonia or nitrate of soda.