148 



STATES OP THE KIVEB PLATE. 



For analyses of grasses, clovers, flesh, blood, bones, &c. 

 see ' Treatise on Sheep-breeding.' 



The constant diminution in the produce of land conti- 

 nuously under crop is thus accounted for, where there is no 

 sufficient restoration made in the form of manure, as is 

 also the deterioration of pasture lands from which gradually, 

 under a system of excessive stocking especially, the more 

 suitable and nutritious grasses disappear. In pasture lands 

 this, however, js not the only cause in operation to preci- 

 pitate the result. On overstocked lands on which the best 

 and most palatable grasses are closely eaten down, there 

 is no sufficient opportunity for such better grasses to seed 

 and reproduce themselves ; so that ultimately the weeds 

 and inferior grasses usurp possession. This is a process 

 which is going on extensively on the sheep estancias of 

 Buenos Ayres, and if certain hmits are not put to it very 

 serious consequences will accrue to the land and stock- 

 owners' interests. 



The perpetual fertility of a soil is maintained by a 

 sufficient restoration to it of the minerals abstracted from 

 it by the crops ; moreover, this fertility or power of pro- 

 duction can be increased by mechanical operations (tillage) 

 efficiently performed, and through the improvement of the 



