VALUE OF ARTIFICIAL MANURES. 31 



If you look at the composition of farmyard manure, you will 

 observe entering into it, a large amount of substances which are 

 present in the soil in abundance, or which in the form of straw 

 or litter can be easily incorporated with the soil, and which are 

 cheap and readily procurable in the market. Now these cheap 

 materials amongst which I would mention lime, magnesia, 

 silica (which is but another name for sand), oxide of iron, alumina, 

 and a few other substances are abundantly in the soil. When 

 supplied in the manure, they do not produce any striking effect, 

 but there are other constituents entering into the composition of 

 farmyard manure, which, when supplied to the soil, produce the 

 most striking effects. The amount of nitrogen in fresh farmyard 

 manure, or in rotten dung, is exceedingly small ; but, notwith- 

 standing this, it exercises a most remarkable effect upon wheal, 

 barley, oats, and grass crops. 



All substances containing nitrogen may be regarded as special 

 manures for cereals and grass crops. Their especial function 

 is to promote the luxurious growth of cereals ; and hence you 

 need not feel astonished to see a remarkable effect following the 

 use of guano, for this is a manure rich in nitrogen, and, in conse- 

 quence of the large amount of ammonia which it contains, pro- 

 duces an extremely beneficial effect on the wheat crop. Another 

 constituent present in farmyard manure, only in small quantities, 

 is phosphate of lime the principal constituent of bones. Bones, 

 as most of you know, consist, as far as their bulk is concerned, 

 principally of phosphate of lime. Now phosphate is extremely 

 useful for root crops. It is required by all agricultural produce 5 

 but experience has shown that it is most beneficially applied 

 to root crops. My time will not permit me to assign the reasons 

 why phosphate of lime, when supplied to the soil in a proper 

 state, is especially useful to root crops ; but I appeal to the 

 general experience of practical farmers, and content myself by 

 saying, rather dogmatically, that phosphate of lime is a special 

 manure for root crops. At all events, it is one of the most 

 important fertilising materials which is found in farmyard 

 manure ; but you will observe that the proportion of bone 

 material, or phosphate of lime, in farmyard manure is but small. 

 There is a class of substances of the name of potash and soda, 

 two substances comprised under the general name of alkalis. 

 These alkalis potash and soda are largely required by all 

 agricultural plants. They are found in the ashes of all agricul- 

 tural produce, and are absolutely necessary for their existence. 

 Now the great value of artificial manures depends just on this, 

 that they concentrate these important fertilising materials 

 important because all soils contain them only in small quantities, 

 and all agricultural produce requires them in larger quantities 



