May 24, 1894] 



NA TURE 



75 



CHEMISTRY APPLIED TO AGRICULTURE. 



I Manures and the Principles of Manuring. By C. M. 

 ' Aikman, B.Sc, F.R.S.E. Pp. xxx., 592. (Edinburgh 

 and London : W. Blackwood and Sons, 1894.) 



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 Ap- 

 I plications to Agriculture and Physiology." In this, | 

 among many bold and startling statements, we find such 1 

 I 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. ' " .-Mso, 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 ol 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 pro- 

 ductive of much good, and stirred up a great deal of 

 interest in agricultural chemistry which led to many im- 

 portant results. Within a year or two before the date 

 mentioned and five or si.t 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 ex- 

 periments ; 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. 



Within a very few years of this date Prof. Johnston 

 published his Lectures, and Cuthbert W. Johnson pub- 

 lished a very useful and interesting book " On the Fer- 

 tilisers. ' It is almost needless to remark that the im- 



NO. 1282, VOL. 50J 



mortal experiments of Rothamsted were put on to a firm 

 and systematic basis in 1S43. 



Since that time agricultural chemistry, including a 

 knowledge of the principles of manuring, has steadily 

 pursued its way, fostered by a host of workers, not 

 only in this country but on the continent, and lately 

 in the United States. The last few j ears have shown 

 some revival of the public interest in the applications of 

 science to agriculture. This has, we think, been brought 

 about partly by the spread of technical education in the 

 rural districts ; but also partly byt he continued low prices 

 of agricultural produce, which make it imperative on the 

 farmer, if he would continue to survive, to use every 

 good implement, mental or otherwise, he can in further- 

 ing his business. 



Although many little books have been lately published 

 in this country on the subject of manures, we may safely 

 say that none of them are so satisfactory as that of Mr. 

 Aikman. Though in some respects incomplete, it is a 

 welcome addition to the literature of the more scientific 

 side of agriculture. The first part of the book is a short 

 historical introduction of 60 pp. ; this is good, but too 

 short. Part ii. is on the principles of manuring. It deals 

 with the fertility of the soil, illustrated by and due to its 

 physical, chemical, and biological properties ; with the 

 functions performed by manures, and the positions 

 occupied by nitrogen, phosphoric acid, and potash in 

 agriculture, and with nitrification in soils. The treat- 

 ment of the biology of the soil is all too scanty. Part iii., 

 more than half the book, treats of manures. The most 

 important chapter is on the most important manure- 

 farmyard manure — and this is well treated. Other 

 chapters are on guano, nitrate of soda, sulphate of 

 ammonia, bones, mineral phosphates, superphosphate.^, 

 basic slag, potassic manures, indirect manures, which 

 include lime, gypsum and salts, the application of 

 manures, manuring of farm crops, the valuation and 

 analysis of manures ; and a final chapter giving the results 

 of some of the Rothamsted experiments. There is a very 

 short chapter on sewage, which is inadequately dealt 

 with, and the minor rrtanures are very scantily treated ; 

 seaweed is not even mentioned as a manure, and rape- 

 cake and other oil-cakes are only casually alluded to. 

 Generally, Mr. Aikman has done his work carefully ^nd 

 well, and presented the results in a clear and readable 

 form, which will commend itself to his readers. .As we 

 confidently expect a new edition ere long, we may perhaps 

 be pardoned for pointing out some of the minor defects 

 of the book. More frequent references should be given 

 to original papers ; this might be done without unduly 

 enlarging the volume. The explanation of '' unit " values 

 of manurial ingredients is hardly intelligible to one who 

 first comes across it here. On p. 380, the last sentence 

 is wrong ; probably the word only is omitted. On p. 43, 

 Beyerinck would hardly recognise his name in the way 

 it is spelt ; why should the vioxA% glycin and .{.'/t'tvcv// be 

 used on consecutive pages as though they denoted 

 ditTerent substances ; why should carnallite be sometimes 

 spelt with a c and sometimes with a X', even in the index ; 

 also why are sylvine and kainite denied the final e usually 

 accorded to minerals in this language.' 



The scheme of experimental plots, on p. 546, would be 

 made more complete by including an eighth plot manured 



