194 RETROSPECT. 



that had been removed during the five years' rotation ; this was 

 done, without doubt, by means of the manure. 



Our supply of manure, therefore, effects only this result, that 

 the soil of our arable land is not rendered poorer than that of 

 meadow land capable of yielding on the same surface 25 cwt. of 

 hay. From a meadow we remove annually, in the hay, as great 

 an amount of the constituents of the soil as we do in the crops 

 obtained from the arable land ; and we know that the fertility of 

 meadow land is as dependent on the restoration of the constituents 

 of the soil, as that of arable land is upon the supply of manure. 

 Two meadows of equal surfaces, but containing unequal quantities 

 of inorganic food, are of unequal fertility under like circumstances. 

 The meadow containing the greatest quantity of the mineral food 

 yields more hay, in a certain number of years, than the other 

 which is poorer in mineral ingredients. 



But if we do not restore to a meadow the constituents of the 

 soil removed from it, its fertility decreases. 



The fertility of a meadow remains the same, not only by treat- 

 ing it with solid or with liquid excrements, but it may be retained, 

 or may be even increased in fertility by the application of mine- 

 ral substances left behind after the combustion of wood or of 

 other plants By means of ashes we can restore the impaired 

 fertility of our meadow land. But by the term ashes, we un- 

 derstand the mineral food which plants received from the soil. 

 When we furnish them to our meadows we enable the plants 

 growing on them to condense carbon and nitrogen on their surface. 



Now, does not the action of liquid and solid excrements 

 depend on the same cause ? For these are but the ashes of 



PLANTS EURNT IN THE BODIES OF MAN AND OF OTHER ANIMALS. 



Is fertility not quite independent of the ammonia conveyed to 

 the soil ? If we evaporated urine, dried and burned the solid 

 excrements, and supplied to our land the salts of the urine, and 

 the ashes of the solid excrements, would not the cultivated plants 

 grown on it — the grarninese and leguminosse — obtain their carbon 

 and nitrogen from the same sources whence they are obtained by 

 the gramiih ae and leguminosae of our meadows ? 



There can scarcely be a doubt with regard to these questions, 

 when we unite the information furnished by science to that sup- 

 plied by the practice of agriculture. 



