Chemistry Applied to Agriculture


IT was rather more than fifty years ago, in the year 1840, that Liebig presented to the British Association his classical report on “Organic Chemistry in its Applications to Agriculture and Physiology.” In this, among many bold and startling statements, we find such sentences as the following:—“As there is no profession which can be compared in importance with that of agriculture, so there is none in which the application of correct principle would be productive of more beneficial effects. Hence it appears quite unaccountable that we may vainly seek for a single leading principle relative to this subject in all the writings of agriculture and of vegetable physiologists.” “Also, when we inquire in what manner manure acts, we are answered by the most intelligent men that its action is covered by the veil of Isis; and when we further demand what this means, we discover merely that the excrements of man and animals are supposed to contain an incomprehensible something which assists in the nutrition of plants and increases their size. This opinion is embraced without even an attempt being made to discover the component parts of manure, or to become acquainted with its nature.” In this, as in other of Liebig's statements, there was much exaggeration. Sir Humphrey Davy, De Saussure, and other labourers in the field of scientific agriculture had not lived in vain. Liebig's writings, however, were productive of much good, and stirred up a great deal of interest in agricultural chemistry which led to many important results. Within a year or two before the date mentioned and five or six years after, not only were most of the more important artificial manures, now extensively used, brought into notice and experimented with, but several important writings on manures and manuring were published. Suffice it to say that to this epoch is due the introduction of guano, of nitrate of soda, and of sulphate of ammonia as manures; and that Mr. Lawes (now Sir John Bennett Lawes) took out his patent for the manufacture of superphosphate in 1842; now nearly a million tons of this manure are made annually in this country alone. Two or three important manures, such as the potash salts of Stassfurt and Thomas' basic slag, are of later introduction. To illustrate the attention then given to the subject of manures and manuring generally, and to these new manures in particular, we may note that the second volume of the Journal of the Royal Agricultural Society of England, published in 1841, contains a paper by the Sibthorpian Professor of Rural Economy at Oxford, Dr. Charles Daubeney, “On the scientific principles by which the application of manures ought to be regulated,” including results of many experiments; also an article by Prof. J. F. W. Johnston, “On Guano,” and the results of experiments by numerous agriculturists with nitrate of soda, saltpetre, bones, and gypsum.

Manures and the Principles of Manuring.

By C. M. Aikman Pp. xxx., 592. (Edinburgh and London: W. Blackwood and Sons, 1894.)

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