Abstract

                                The principle underlying the use of fertilizers, namely, the necessity of add- ing plant food to the soil, was understood in a general way even in the early days of civilization. It was only about a century ago, however, that the science of plant nutrition and the requirements of the soil for certain elements, in which it is liable to be deficient, began to be clear as a result of the researches of de Saus- sure and Liebig on the Continent and Lowes and Gilbert in England. The ver- satile i awes was not only one of the most brilliant pathfinders in agricultural science but was also the first manufacturer of a chemical fertilizer, namely super- phosphate. Phenomenal progress has since been made in the manufacture of chemical fertilizers in Europe, America and Japan, and today the combined. world production in the case of some of the important fertilizers is computed in terms of millions of tons. The fertilizer industry by its effect on the cost of production of sulphuric acid has given a tremendous impetus to the development of the heavy chemical industries. Since the World War of 1914-18 the synthetic manufacture of fertilizers has been greatly developed.

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