ENGLISH AGRICULTURE. 163 



special manures. The disadvantage of a special manure is 

 that it tends towards exhaustion, although that result may 

 be very remote. If we continually apply nitrate of soda 

 to the soil, and increase our crops thereby, those crops 

 must search for and appropriate the mineral constituents 

 of the soil, and hasten both its immediate and ultimate 

 exhaustion. This is an objection which is sometimes 

 urged by persons not conversant with the practice of agri- 

 culture. But in the ordinary course of farming, what with 

 the use of farmyard dung, the importation of food for live 

 stock in the form of cakes, purchased corn, maize, and hay ; 

 and what with the rotation of manures employed, which is 

 as much a fact as the rotation of crops, we think in the 

 ordinary course of good farming there is not any fear of 

 special manures being used in such a manner as to rob the 

 ground to any injurious extent. 



There is another view of the case which is worthy of your 

 attention. Special manures, although tending to exhaust the 

 soil, and also somewhat evanescent in their effects, may be so 

 employed as to produce a permanent increase in the fertility 

 of a farm. By the application of nitrate of soda and super- 

 phosphate, both of which are special manures, we greatly 

 increase our yield of straw, and of our hay and root crops. 

 When these crops are consumed by live stock upon the 

 farm, they add largely to the amount of dung which is pro- 



luced. Therefore, in the course of husbandry the . com- 

 iratively temporary effect of these manures is converted 

 ito the more permanent benefits, whatever they may be, 



rhich follow the production of large quantities of farmyard 



lung. 

 The value of special manures is most apparent in the follow- 



ig circumstances. First of all, where you have a soil which 



either from analysis or other indications you believe to bo 



leficient in a certain constituent for example, lime. In such 



M 2 



