310 SOILS AND MANURES 



acid. Moreover, the constituents of the urine are present 

 in a soluble state, and are therefore immediately avail- 

 able to plants, whereas those of the dung are present in 

 an insoluble condition and only become available as the 

 organic matter decays. It is evident therefore that 

 contrary to what is very generally believed by farmers 

 the urine Or liquid excrement is much more valuable 

 for manurial purposes than the dung or solid excrement. 



The proportion of water in urine is necessarily always 

 large, ,but is extremely variable. It is usually over 

 85 per cent., and sometimes as much as 98 per cent. It 

 depends so largely upon the quantity of water drunk or 

 taken in with the food, and the amount lost by per- 

 spiration, that it can scarcely be said to be characteristic 

 of the different kinds of animals. It may be said, how- 

 ever, that, under normal and similar conditions, the urine 

 of horses is generally more concentrated than that of 

 cows ; also that the urine of sheep is generally more con- 

 centrated, and of pigs more dilute than that of either of 

 the former. 



The proportion and composition of the solid matter of 

 the urine, like that of the dung, is affected by the charac- 

 ter and quantity of the food supplied to the animal, but 

 to an even larger extent. This may be illustrated by 

 the example on p. 811, showing the quantities and com- 

 position of dung and urine produced by cows fed on 

 mangolds and lucerne hay respectively. In the first table 1 

 the data are given as percentages of the fresh excrement, 

 and in the second table as percentages of the dry matter. 

 The third table shows the total quantities of the excreta, 

 and the different'constituents of the same. 



It will be seen that both the dung and urine produced 

 by the animals fed on lucerne hay contain a larger pro- 

 portion of solid matter, but the most striking difference 



1 "Warington, " Chemistry of the Farm." 



