598 The Lois Weedon Plan of Groicing Wheat. 



M. Kuhlmann himself says, — 



" Neither must the nitrogen be held in too stable combinations, as it exists 

 in coal, the direct employment of which does not conduce to the fertilisation of 

 the soil, but which by distillation yields a very fertilising ammoniacal liquid. 

 Do not the same reflections apply to an objection raised against the necessity of 

 the employment of nitrogenized manures ; namel}^, that a hectare of land to the 

 depth of 20 to 25 centimetres contains ammonia in quantities infinitely greater 

 than those by means of which Ave seek to provide it with the elements of 

 fertility ? In my opinion, it is not sufficient that distillation should enable us 

 to separate ammonia from the soil ; it is necessaiy that this ammonia should be 

 accessible to the plant without the aid of hre or of other energetic agents. 



" There is moreover a reply to the objections stated above in the facts 

 themselves ; a hectare of land may contain enough of nitrogen held in stable 

 combinations to produce 5000 or even 10,000 kilogrammes of ammonia, and 

 yet give poor crops. If we apply to the same land 250 kilogrammes of 

 ammonia, in the form either of ordinary manure or of pure ammoniacal salt, 

 the fertility will be doubled. 



" Agriculture is, above all, a science of facts ; it is in experience that it must 

 seek the basis of its theoretical laws." * 



These, then, are the opinions of chemists as well known by 

 their investigations in the field as by their researches in the 

 laboratory. 



Having now to record some recent determinations of nitrogen 

 in soils made at Rothamsted, it may be well first to dwell for a 

 moment on some of the previously published data of this kind 

 Avhich have been quoted by Baron Liebig. With regard to the 

 determination of nitrogen in soils, made by Dr. Krocker in 

 1846, in the Giessen laboratory, it appears, by reference to the 

 original paper (Annalen der Chemie and Pharmacie, Band 58, 

 pp. 381-8), that he only made a single determination on each of 



contenir assez d'azote engage dans des combinaisons stables, pour representer 

 jusqii'a 10,000 kilog. d'ammoniaque, et donuer ne'anmoios des re'coltes chetives, 

 tandis que, fume avec 250 kilog. d'ammoniaque a I'e'tat d'engrais, il rendra, par la 

 culture, des produits satisfaisants." — Ibid. p. 78. 



* " II lie faut pas non plus que 1' azote soit engage dans des combinaisons trop 

 stables, comme cela existe pour la houille, dent I'emploi direct ne donne pas lieu a la 

 fertilisation du sol, mais dont la distillation deplace un liquide ammoniacal tres- 

 fertilisant. Les memes reflexions ne s'appliquent-elles pas a une objection produite 

 centre la necessite de I'emploi des engrais azotes; k savoir qu'un hectare de terre 

 a 20 ou 25 centimetres de profondeur contient des quantites d'ammoniaque infini- 

 ment supe'rieures a celles au moyen desquelles on cherche h, lui donner des ele- 

 ments de fertilite' ? Dans ma pense'e, il ne suffit pas que la distillation permette de 

 de'placer de rammoniaque de la terre, il faut que sans le secoursdu feu oud' agents 

 energiques cette amnioniaque puisse etre offerte a la plante. 



" II y a d'ailleurs h. I'objection presentee ci-dessus une reponse dans les faits 

 meme. Un hectare de terre pent contenir assez d'azote engage' dans des combi- 

 naisons stables pour produire 5U00 et meme 10,000 kilogrammes d'ammoniaque 

 et donner cependant des recoltes chetives. Si Ton fume cette terre avec 250 kilo- 

 grammes d'ammoniaque a I'e'tat d'engrais ordinaire ou de sel ammoniacal pur, la 

 fertilite' sera double'e. 



" L' agriculture est, avant tout, une science de faits, c'est dans I'experience 

 qu'elle doit chercher la base de scs lois theoriques." — Annales de Chinu'e et de 

 Physique, vol. xx., 1847, p. 271. 



