312 Agricultural Chemisti'y. 



active mineral constituents extracted from the soil in the crops 

 by the use of such manures, and the less the quantity of these 

 mineral constituents restored to the soil in these manures, the 

 more rapidly does the capital of the proprietor diminish in value 

 by this system of exhaustion. 



As in the case of working men and horses, the exhaustion is 

 directly proportional to the work performed. By rightly selected 

 food the power is restored, in men as in horses, of performing on 

 the second day the same amount of work as on the day preceding. 

 Every misproportion in the constituents of the food causes a 

 misproportion in the force produced, and, if continued, ultimately 

 gives rise to a morbid condition. 



The manure we place on the land has the same relation to the 

 plants which are to grow on it as the flesh and bread have to the 

 man, the hay and oats to the horse. By rightly selecting the 

 food of plants we enable the land, in the second year, to yield 

 the same produce as in the preceding one. A misproportion 

 among the elexnents of the manure changes and disturbs, in a 

 shorter or longer time, the fertility of the land. 



It is because farmers did not know this natural law, or because 

 they do not keep it in view in its entire strictness, that they have 

 made, and still make, countless experiments to no purpose. To- 

 day, nitrogen and phosphorus constitute the panacea, the uni- 

 versal medicine, with which they propose to cure the land which 

 has become diseased ! 



I am of opinion that we may make a free and unlimited use of 

 guano and amnioniacal salts, if we take the precaution of adding 

 simultaneously icith the guano a certain quantity of the ashes of hard 

 tcood, and with the sulphate of ammonia a certain quantity of phos- 

 phate of lime and of hard- wood ashes. In pi-actice, however, this 

 cannot he accomplished. The more use the farmer makes of special 

 artificial manures, the less farm-yard manure ivill he use ; and 

 the more imperatively will the necessity make itself felt, of replacing 

 the deficient constituents hy a supply from without, or, what amounts 

 to the same thing, of making artificial manures more and more ana- 

 logous in comjiosition to farmyard manure. 



It would be a great error to attempt to make farmers believe 

 that all the land of an extensive country is deficient in nitrogen 

 and phosphorus only, and has an excess of all the other consti- 

 tuents indispensable to cultivated crops. It is a fact, that not 

 thousands, but hundreds of thousands of fields have the same 

 quality as those of Schattermann, the produce of which, when 

 manured with ammoniacal salts alone, diminishes instead of 

 increasing. 



The greater the amount of produce derived from land by tbe 

 use of artificial manures, such as do not restore to the soil all the 



