The Lois Weedon Plan of Growing Wheat. 597 



last number of this Journal, which is published as an inde- 

 pendent work in Germany. 



M. Bousslngault says, — 



" Latterly, M. Liebig has sought to estaHish that the mineral matters, the 

 alkaline salts, are the only efllcacious agents ol' manures, supporting this 

 assertion hy analyses which indicate in arable land, even when unmannred, a 

 considerable proportion of ammonia ; from which it has been concluded that, as 

 the soil always contains a more than sufficient amoiuit of nitrogenized matters, 

 there is no necessity to supply them to it.* " 



And further, — 



" This alkali was determined by calcining the soil with a mixture of soda 

 and lime. We know that, by this method, the nitrogenized substances are 

 transformed into ammonia ; but the process does not enable us to decide 

 whether this ammonia was entirely formed in the matter examined. In fact, a 

 soil might furnish by analysis a very large proportion of the volatile alkali, 

 and yet we might not be justiiied in affirming that it contains, I will not say 

 this alkali already formed, but even putrescible nitrogenized substances, that 

 is to say those v.'hich are efficacious in vegetation. Thus we might extract 

 from a soil abounding in peaty del^ris, from a bituminous schist, large quanti- 

 ties of ammonia, without, on that account, being sure of obtaining advantageous 

 crops from such soils. 



" However, it is according to the determinations of nitrogen, that M. Liebig 

 states that a hectare of arable land, taken to a depth of 25 centimetres, con- 

 tains, not the elements of ammonia, but 2000 to 10,000 kilogrammes of 

 ammonia itself; a result presented as an objection against the necessity of the 

 employment of nitrogenized manures. M. Kulhmann has remarked, with 

 reason, that there is an answer to this objection in the facts themselves, and it 

 is, that a hectare of land may confain enough of nitrogen held in stable com- 

 binations to represent as much as 10,000 kilogrammes of ammonia, and 

 nevertheless give meagre crops, whilst, if dressed with 250 kilogrammes of 

 ammonia in the form of manure, it will yield, after cultivation, a satisfactory 

 produce." f 



* " Dans CCS derniers temps, M. Liebig a cherclid a etablir que les matieres 

 minerales, les sels alcalins, soiit les seals agents efficaces des engrais, en apjniyant 

 cette assertion sur des analyses (lui indiqueraient dans la terre arable, alors nieme 

 qu'elle u'est pas funie'e, une forte proportion d'ammoniaque ; d'oii ron a couclu 

 que le sol coutt-naut toujours une dose plus que suffisante de niateriaux azote's, il 

 n'y a pas lieu de lui en fournir." — Economic L'unile, tome ii. p. 77. 



t " On a dose cet alcali en calcinant la terre avec un mc-lange de soude et de chaux. 

 On salt que, par cette methode, les substances azotees sont transfovme'es en ammo- 

 niaque; mais It; procede ne permet pas de decider si cetle animoiiiaque etait toute 

 fonnee dans la matiere exnniinee. En cffct, une terre pourrait fournir ii I'analyse 

 inie tres-forte proportion d'alcali volatil, sans (jue pour ceia on filt en droit d'affirmer 

 qu'elle contieut, je ne veux pas dire cet alcali tout constitue, mais nienie dcs sub- 

 stances azotecs j)Utrescil)les, c'est-ii-dire, efficaces dans la vegetation. Ainsi, ou 

 extrairait d'un sol abondant en dt'liris tourbeux, d'un sehiste bitunnneux, de fortes 

 ([uantites "d'ammoniaque, sans ([ue, pourcela, ou soil assure deretirerde semblables 

 terrains des rt-coites avantageuses. 



" ("ependant, c'est d'apres des dosages d'azote, (pie M. Liebifr trouve qu'ini hec- 

 tare de terre arable, sur une profondeur de 25 centimetres, contient, non pas les 

 e'lemens de I'ammoniaque, mais 'iUOO ii l(>,(i(i(t kilog. d'ammoniaque en nature, 

 rt^sultat pre'sente comme une objection contre la nccessite de rintervention des 

 engrais azotes. M. Kullimaim a fait remarquer, avec raison, qu'il yah, cette 

 objection une reponse dans les faits mcmes, et c'est qu'un hectare de terre pent 



