ARTIFICIAL MANURING. 14l 



gredients by tlie plant ; lie must remove the impediments 

 which diminish their etieet. 



The favourable influence ■which bone earth, gypsum, and 

 nitrate of soda, exercise on the fields has induced many- 

 farmers to the belief that in applying- them they can dis- 

 pense with manure or with the other elements of the soil ; 

 it requires, however, only little attention to see the great 

 error of this opinion. We observe that the eliect of these 

 substances is not equal on all fields ; in one place the amoimt 

 of produce is increased by the lime, by the bone earth, and 

 by g'vpsum ; in another country, or on other fields, these 

 substances in no way favour veg'etation. From this arises 

 the contradictory views of farmers reg-arding- these matters 

 as manures. If one farmer thinks the liming" of his fields 

 quite indispensable for rendering- them fertile, another de- 

 clares that lime produces no effect at all. 



The reason of this difference is very simple. The exami- 

 nation of a soil upon which lime has had no effect shows 

 that it was already rich in this substance ; it further shows 

 that its effect extends only to those kinds of soil in which 

 lime is wanting-, or in which it is found in too small a 

 quantity, or in a condition which is not suited to its assimi- 

 lation by the plant. Lime especially serves for resolving- 

 the silicates of alumina (clay), and consequently it cannot 

 fertilize soils in which clay is wanting- — for instance, sandy 

 soils. It must be apparent to every one, that on the cal- 

 careous and g-ypseous fields of France and Eng-land, one- 

 half per cent, of g-ypsum or lime can have no influence at 

 all on vegetation. This can be said with equal justice of 

 bone ashes, and of every other mineral substance serving- 

 for the nourishment of plants. 



If these substances exercise a favourable effect, some of 

 the constituents of the soil or manure are restored which 

 are indispensable to the nourishment of plants, and which 

 have been wanting- in the soil. If this be the case, the other 

 bodies, equally necessary, must be present in sufficient 

 quantity. On a field in which sulphate of lime has acted 

 favourably, and in which clover had been cultivated as 

 fallow without it, the crop was 2200 lb. of clover hay, 

 in which 53 lb. of potash were removed. On the same 

 field, after it had been g-ypsed, 8,000 lb. of hay were 

 produced, which contained 191 lb. of ])otash. If this 

 potash had not been present in the soil, the g-ypsum would 

 have had no effect — the crop would not have been increased. 



