84 THE CHEMISTRY O:^ THE FARM 



price. In the majority of cases, however, the special 

 manuring will only be required to supplement the 

 general manuring by farmyard manure. Under these 

 circumstances it would seem best, from a chemical 

 point of view, to apply the farmyard manure to those 

 crops which most require potash, or which stand most 

 in need of a general manuring ; such crops would be 

 meadows mown for hay, artificial grasses, turnips, and 

 potatoes. 



As the whole object of artificial manuring is to 

 supplement the deficiencies of the soil, it is highly 

 desirable that a farmer should ascertain by trials in 

 the field what is the actual amount of increase which 

 he obtains from the application of the manures he 

 purchases. A few carefully made experiments will 

 teach him what his land and crops are really in need 

 of. Should he use superphosphate as well as nitrate 

 of sodium for his wheat? What dressing of the 

 nitrate is most economical? Is superphosphate alone 

 sufficient for his turnip crop, or should ammonia or 

 nitrate be employed as well? What is the smallest 

 quantity of superphosphate sufficient for the crop? 

 Will it pay to use potassium salts for his seeds, his 

 pasture, or his potato crop ? These aiid many other 

 questions can only be answered by trials on his own 

 fields. On the farmer's knowledge of such facts will 

 depend the economy with which he is able to use 

 purchased manures, which are by some wastefully 

 employed. 



Influence of Climate and Season. — The influence of 

 weather upon crops is far greater than the influence of 

 manure. 



