144 On the Application ■ 



other — just as the nourishment of an animal depends both upon 

 a healthy state of his organs of digestion and upon a due supply 

 of nutritious aliment. 



There is, however^, a third description of manures every day 

 coming more and more into vogue, which are by some considered 

 to supply food, and by others regarded as acting in the capacity 

 of stimulants to plants. 



To the latter class belong those various saline and earthy com- 

 pounds, which a more extended acquaintance with chemistry, and 

 an increased communication with foreign countries, have brought 

 within the reach of the farmer : such, for example, as the nitrates 

 of soda and of potass — the bone-earth, so extensively employed 

 upon our turnip-fields — the gypsum, so useful on clover and grass 

 land — and numerous other mineral substances, which will imme- 

 diately occur to you. 



To ascertain in what manner these latter kinds of manure 

 operate in fertilizing the soil is not, as some might suppose, a 

 mere object of curiosity or of speculative interest, since its decision 

 will afford us the means of determining the proper proportion in 

 which to apply them, the kind of soils which will be most benefited 

 by their addition, and many other points of an equally practical 

 character. 



Whether these substances ever operate in any other manner, 

 as, for example, as stimulants, may be afterwards discussed ; but 

 that some of them at least are serviceable, by providing those con- 

 stituents which the soil only contains, if at all, in limited quan- 

 tities, cannot, I think, be disputed. 



With regard to bone-earth, which is now so extensively applied 

 to the lands of this country, there can be no doubt that phosphate 

 of lime, which constitutes its predominant ingredient, is secreted 

 by the organs of a plant, and supplies the place of that which 

 had been drawn from the soil by preceding crops. Its peculiar 

 adaptation for turnips, which contain a larger per centage of 

 phosphoric acid than any other of the ordinary crops of this 

 country ; its usefulness on dairy-farms, where a great quantity of 

 phosphate of lime is continually drawn from the soil in the form 

 of butter and cheese sold off the estate ; and its serving to a 

 certain extent as a substitute for farm-yard manure (the solid part 

 of which consists in a great degree of this same substance), are 

 circumstances all lending support to such an opinion. Now, with 

 the view of taking advantage in our practice, as far as possible, 

 of a theory which seems so plausible, as well as of testing its truth 

 still further by the results of our experience, I conceive it would 

 be a very useful exercise, if each agriculturist, besides entering in 

 a book the amount per acre of the crops obtained, and of the 

 different kinds of manure applied, were also to calculate the weight 



