370 



Agricultural Chemistry. 



No. 12. 



Agricultural Chemistry. 



FROM LIEBIG. 



" There is no profession which can be com- 

 pared in importance with that of agriculture; 

 for to it belongs the production of food for 

 man and animals: on it depends the welfare 

 and development of the whole human species, 

 the riches of the state, and all commerce. 



"There is no other profession in which the 

 application of correct principle is productive 

 of more beneficial effects, or is of greater and 

 more decided influence. Hence it appears 

 quite unaccountable, that we may vainly 

 search for one leadiyig principle in the writings 

 of agriculturists and vegetable physiologists. 

 The methods employed in the cultivation of 

 land are different in every country and in 

 every district: and when we inquire the 

 causes of these differences we receive the 

 answer, that they depend upon circumstances. 

 No answer can show ignorance more plainly, 

 since no one has ever yet devoted himself to 

 ascertain what these circumstances are. Thus 

 also, when we enquire in what manner ma- 

 nure acts, we are answered by the most in- 

 telligent men, that its action is covered by 

 the veil of Isis ; and when we demand further 

 what this means, we discover, merely, that 

 the excrements of men and animals are sup- 

 posed to contain an incomprehensible some- 

 thing which assists in the nutrition of plants, 

 and increases their size ; this opinion is em- 

 braced without even an attempt being made 

 to discover the component parts of manure, 

 or to become acquainted with its nature. 



"In addition to the general conditions, 

 such as heat, light, moi.sture and the compo- 

 nent parts of the atmosphere, which are ne- 

 cessary for the growth of all plants, certain 

 substances are found to exercise a peculiar 

 influence on the development of particular 

 families. These substances either are already 

 contained in the soil, or are supplied to it in 

 the form of the matter known under the gen- 

 eral name of manure. But what does the soil 

 contain, and what are the components of the 

 substances used as manure 1 Until tiiese 

 points are satisfactorily determined, a rational 

 system of agriculture cannot exist. The 

 power and knowledge of the physiologist, of 

 the agriculturist and chemist, must be united 

 for the complete solution of these questions; 

 and in order to attain this end, a commence- 

 ment must be made. 



" The general object of agriculture is, to 

 produce in the most advantageous manner 

 certain qualities, or a maximum size, in cer- 

 tain parts or organs of particular plants. Now, 

 this object can be obtained only by the appli- 

 cation of those substances which we know to 

 be indispensable to the development of these 

 parts or organs, or by supplying the condi- 



tions necessary to the production of the quali- 

 ties desired. The rules of a rational system 

 of agriculture should enable us, therefore, to 

 give to each plant that which it requires for 

 the attainment of the object in view. The 

 special object of agriculture is, to obtain an 

 abnormal development and production of 

 certain parts of plants, or of certain vegetable 

 matter, which are employed as food for man 

 and animals, or for the purposes of industry. 

 " The means employed tor effecting these 

 two purposes are very different. Thus, the 

 mode of culture, employed for the purpose of 

 procuring fine pliable straw for Florentine hats 

 is tlie very opposite to that which must be 

 adopted in order to produce a maximum of 

 grain from the same plant. Peculiar methods 

 must be used for the production of nitrogen 

 in the seeds; others, for giving strength and 

 solidity to the straw; and others again must 

 be followed, when we wish to give such 

 strength and solidity to the straw as will en- 

 able it to bear the weight of the ear. We 

 must proceed in the culture of plants in pre- 

 cisely the same manner as we do in the fat- 

 tening of animals. The flesh of the stag and 

 roe, or of wild animals in general, is quite 

 void of fat, like the muscular flesh of the 

 Arab; or it contains only small quantities of 

 it. The production of flesh and fat may be 

 artificially increased ; all domestic animals, 

 for example, contain much fat. We add to 

 the quantity of food, or we lessen the proces- 

 ses of respiration and perspiration by prevent- 

 ing motion. The conditions necessary to 

 effect this purpose in birds are different from 

 those in quadrupeds; and it is well known 

 that charcoal powder produces such an ex- 

 cessive growth of the liver of a goose as at 

 length causes the death of the animal. 



"The increase or dimunition of the vital 

 activity of vegetables depends upon the heat 

 and solar light, which we have not arbitra- 

 rily at our disposal : all that we can do is, to 

 supply those substances which are adapted to 

 assimilation by the power already present in 

 the organs of the plant. But what are these 

 substances'! They may easily be detected 

 by the examination of a soil, which is always 

 fertile in given cosniical and atmospheric 

 conditions: for it is evident, that the know- 

 ledge of its state and composition must enable 

 us to discover the circumstances under which 

 a sterile soil may be rendered fertile. It is 

 the duty of the chemist to explain the com- 

 position of a fertile soil, but the discovery of 

 its proper state or condition belongs to the 

 agriculturist; our present bu.siness lies only 

 with the former. 



" Arable land is originally formed by the 

 crumbling of rocks, and its properties depend 

 on the nature of their principal component 

 parts. Sand, clay and lime, are the names 



