358 
The Science of Agriculture. 
TMay, 
such as clover, sainfoin, lucerne, potatoes, and vines, and in 
these potash is the dominant ingredient. 
Now what M. Ville terms “normal manures” contain 
calcic phosphate, potash, lime, and nitrogenous matter, 
differing only in the respective proportions of these 
four substances. By varying, therefore, their relative 
proportion according to the necessities of the particular 
plants for which they are required, the principle of dominant 
constituents can be applied to every possible condition which 
may arise, thereby meeting the requirements and advancing 
the interests of every description of farming. 
It is not necessary to restore to the soil, weight for weight, 
constituent for constituent, all that is taken from it, but the 
four constituents named above are essential, and must always 
be added. Analyses of farmyard manure show that it con- 
tains the four constituents which it is essential to restore 
to the soil, but it also contains carbon, hydrogen, and oxygen ; 
also sodic chloride, magnesia, soda, silica, ferric oxide, &c., 
all of which are abundantly contained in the poorest soils, 
and which do not therefore increase the value of manure. 
Farmyard manure therefore owes all its efficacy to the four 
essential constituents mentioned above. But we have just 
shown that each of these constituents with regard to the 
three others fulfils functions that are in turn subordinate 
or predominant, according to the nature of the plants to be 
grown ; with farmyard manure, however, there is no possible 
division ; its composition cannot be varied. The only 
alternative, then, is to use it in conjunction with chemical 
manures. In practice the quantity of farmyard manure usu- 
ally applied to an acre of land is, we believe, from 16 to 
20 tons, in which quantity the four essential constituents 
form only about a fortieth of the whole mass. Their 
proportions are as follow : — 
To place the land under the proper conditions for high culti- 
vation the amount of the fertilising substance in the farmyard 
manure must be at least doubled by means of chemical 
manures, and in the case of each particular plant it is 
necessary to concentrate that chemical agent which is 
especially favourable to its growth. It must also be remem- 
bered that one-third of the nitrogen is lost to the soil on 
o 0 
Nitrogen ... 
Potash 
Phosphoric acid 
Lime 
181 lbs. per acre. 
164 
98 
352 
