SHEEP AS IMPROVERS OF SOIL FERTILITY 5 



outside sources, and yet the pastures on these hills are 

 more rather than less abundant than they were decades 

 ago. This fact finds demonstration in the comparison of 

 the carrying power of the grasses. Since lands that are 

 judiciously grazed by sheep from year to year become 

 richer, the question naturally arises as to what will be the 

 limit of the enriching process, or as to whether it has any 

 limit. The answer to both questions will depend upon 

 the amount of plant food available and inert in the strata 

 of soil and subsoil in which the plants feed. It will be 

 observed that the increase in fertility through such graz- 

 ing, at least where legumes are absent, comes through 

 transformation of fertility. Such transformation relates 

 first to change in form, and second, to change in place. 

 Now, if the supply of these nutrients is sufficient for 

 indefinite use, there will be similar increase in fertility in 

 the lands thus grazed. If, on the other hand, the supply 

 is insufficient for such use indefinitely, then a time would 

 come when the power of such lands to carry sheep would 

 grow less, unless aided from some outside source. Hap- 

 pily, the supply of inert plant food materials in the soil 

 is sufficient to sustain plant growth indefinitely, in some 

 forms at least, otherwise the prairies could not have main- 

 tained for long centuries in undiminished volume the 

 grasses that grow upon them. 



Sheep manure valuable The droppings of sheep are 

 valuable, first, because of the chemical constituents ; sec- 

 ond, because of the readily available condition ; third, be- 

 cause of the even way in which they are distributed on 

 the soil ; and fourth, because they are distributed where 

 most needed. In all of these respects it would probably 

 be correct to say that the droppings of sheep are more 

 valuable than the droppings of any other class of quadru- 

 peds kept upon the farm. This is certainly true when 

 these influences are considered together. 



The analyses of the fertilizer obtained from the differ- 

 ent classes of domestic animals will, of course, vary with 



