CROPS. 47 



the soil will not be diminished at the end of the rotation. 

 At the same time the most economic result will have been 

 obtained from the manures employed, for each manure 

 will have been supplied to that particular crop with which 

 it yields the most remunerative result. 



It is doubtless possible by means of rotations manured 

 on the above principles to farm successfully with the sale 

 of all the crops produced, and without the use of farmyard 

 manure ; this is possible at least so long as artificial 

 manures can be obtained at a low price. In the majority 

 of cases, however, the special manuring will only be 

 required to supplement the general manuring by farm- 

 yard 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 pasture, seeds, turnips and potatos. 



The economic value of potash manures varies much on 

 different soils. As potassium salts are an expensive 

 manure, the farmer should always ascertain by means of 

 small field experiments whether they will, in his case, 

 yield a remunerative result, before employing them on 

 any large scale. 



As the whole object of artificial manuring is to supple- 

 ment 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 care- 

 fully made experiments will teach him what his land and 

 crops are really in need of. Should he add superphosphate 

 with the nitrate of sodium for his wheat ? What dressing 

 of the nitrate is most economical ? Is superphosphate alone 



