272 



J. B. LAWES AND JUSTUS VON LIEBIG, 



for turnips — that 12 cwt. of sulphate of lime gave less 

 than 53 tons; and the same amount of sulphate of 

 lime with 3 cwt. of sulphate of ammonia in addition 

 gave only 43 tons, while superphosphate gives 14 J 

 tons. 



We might extract from these extensive and long- 

 continued expsriments many more similar results for 

 other years, but surely we have given enough to show 

 that so far as applied to wheat, the mineral theory, as 

 taught in the extracts we have given from Liebig and 

 his followers, is at fault; and also that for turnips^ 

 while the rain and atmosphere is capable of supply- 

 ing to a great extent the ammonia they require, and 

 that it is partly true that the crop "increases or di- 

 minishes in a direct ratio with the supply of mineral 

 elements capable of assimilation;" yet it is evident 

 that the proportion in which mineral elements are 

 required, are precisely the opposite of what an analy- 

 sis of the ashes of the turnip would lead us to ex- 

 pect.* The experiments in Geescroft, on beans, peas, 

 and tares, and which contain such a large amount of 

 nitrogen, are benefitted little if any by an application 

 of ammonia or nitrogen. The same, to a certain e.x- 

 tent, may be said of clover. There is evidently a 

 great difference in the manurial requirements of wheat, 

 and probably of the other cereals, and those of tur- 

 nips, beans, peas, tares, and clover. The mineral the- 

 ory of Liebig, indeed, points out a difference, but it 

 is the very reverse of what the above experiments 

 and others which might be brought forward, show to 

 be the case. 



Liebig claims these experiments as a practical con- 

 firmation of his theory; and by suppressing some of 

 the principal facts, mistaking others, and seizing on 

 one or two results that are manifest exceptions to the 

 general indications of the experiments, and by a se- 

 ries of ingenious special pleading?, he endeavors so to 

 twist the results as to make them sanction the mine- 

 ral theory. Let us examine the arguments of the 

 great chemist. 



From the facts that the unmanured wheat plot 

 yields annually about 18 bushels of wheat per acre, 

 that the addition of a great variety of mineral ma- 

 nures give little or no increase, and that the addition 

 of ammonia alone gives a great increase, we had con- 

 cluded that this field contained an abundance oj all 

 the mineral elements of plants capable of assimila- 

 tion, and that the reason why it produced only 18 

 'bushels per acre, instead of 28, as when ammonia was 



* Our limited space bas compelled u.g to leave out the results of 

 repeated applications of potash, (of which the turnip ash cont^iins 

 pome 40 per cent.,) soda, magnesia &c., but we may remark that 

 they were attended with little or no benefit. 



used, was to be attributed to a lack of ammonia. In 

 other words, that wheat on this soil, cultivated after 

 the most approved methods, hand-hoed thrice in the 

 spring, abounding in all the mineral elements oJ 

 plants, was not able to obtain sufficient amnionic 

 from the atmosphere for a maximum crop. Were 

 this admitted, the dearly cherished mineral theon 

 must be given up; and Liebig, therefore, endeavor: 

 to prove that the reason why only 18 bushels per acn 

 were obtained, is attributable to a deficiency of avail 

 able minerals. lie asserts that the cause of the ben 

 eficial effect of the sulphate of ammonia ia due to it 

 solvent action on the phosphates of the soil; and Iha 

 it simply or principally acted by rendering an increi 

 sed amount of the mineral elements of the soil, cap; 

 ble of assimilation. We would ask, in reply, if ma; 

 imum wheat crops were not obtained from lack ( 

 soluble jiliosphates, &c., why it was that an applic; 

 tion (if soluble phosphates, &c., did not increase tb 

 crop? They were used in various forms and propo 

 tious, without stint, yet they gave no increase, an 

 Lihuig's own patent wheat manure failed. If, mor 

 over, sulphate of ammonia acts merely as a solvei 

 of phosphates, &c., how does it happen that the larj 

 amount used on some of the turnip plots is attende 

 with little or no increase, while soluble phosphat 

 artificially applied, give an astonishing increase? 



It is impossible to answer these questions, and e 

 cordingly Liebio endeavors to show that the increa 

 of trunips, from an application of superphosphate 

 lime, is not due to the soluble phosphate of lii 

 which it contains, but to the sxdphate of lime nee 

 sarily associated with it. English farmers will 

 glad to learn that it is simply the sulphate of lime t 

 superphospliate contains that benefits their turr 

 crop, and thit they can obtain the same effect ve 

 much cheaper from gypsum or plaster. We have 

 doubt that half a million dollars worth of superphi 

 phate was applied to the turnip crop of England I, 

 year, the greater portion of which might have be 

 saved by a knowledge of the fact discovered by P 

 fessor Liebig ! ! Some will ask on what evider 

 our author bases this opinion. We answer, on c 

 solitary result, taken from Mr. Lawes' experiments 

 a result in direct contradiction to the general indi^ 

 tions of the investigation, and in opposition to i 

 results of other experiments on turnips, with sup 

 phosphate, sulphate of lime, and sulphuric acid- 

 result, in short, which is simply a typographical n 

 take. LiEEiQ says: "A like plot in 1845, which 

 ceived 12 cwt. of gypsum, (residue from the prepa 

 tion of tartaric acid,) and 10 cwt. of rape-ca 



