THE NUTRITION -OF THE EOOT 



57 



the shorter decayed manure. Of course such manuring is 

 not always seasonable, and in each case the gardener or farmer 

 has to consider whether he ought to change the mechanical 

 naturfe of his soil, or need only enrich his field with concen- 

 trated mineral manures. For though stable manure contains 

 all the necessary ingredients, it does not contain them in so 

 concentrated a form as artificial manures. To give an approxi- 

 mate idea, of the nutritive value of stable manures, we append 

 the mean values published in Mayer's "Agricultural Chemis- 

 try," and based upon Heiden's calculations. The following 

 amounts are contained in the excrements of the 



Horse. 



