pedal Jfrrtilinre of the Jfarm. 



HAT special manures are, generally speaking, has already 

 been explained. They contain one, two, or more valu- 

 able constituents of plant food, but are not sufficiently 

 complex in composition to keep up the fertility of 

 soils. They must, however, be regarded as highly use- 

 ful under the following circumstances : (1) When a soil 

 is deficient in some particular element of fertility, as 

 lime, magnesia, or phosphates ; (2) When a crop has 

 some particular requirement ; (3) When soils are in 

 high condition, and it is undesirable to stock them further with artificial 

 fertility, special manures may be employed to bring out, and possibly to 

 reduce their surplus wealth, by stimulating the growth of heavy crops. 



USES AND ABUSES OF SPECIAL MANURES. The first two cases in which 

 special manures have just been recommended need not detain us further. 

 But the third case, in which special manures are employed as a " whip," 

 requires a little explanation. 



If nitrate of soda is applied to a wheat crop, the usual effect is a con- 

 siderable increase in the yield both of straw and grain. Since nitrate of 

 soda contains only one important constituent of plant food nitrogen ; 

 and since the increased yield of wheat, owing to the application, removes 

 from the soil a certain proportion of earthy matter as well as nitrogen, it 

 is evident that the soil has been drawn upon to a greater extent than it 

 would have been without the application. In this case, then, the nitrate 

 of soda has actually reduced the stock of wheat ingredients in the soil. A 

 soil thus treated year after year would be sooner exhausted than one cul- 

 tivated without the aid of a manure of this class. This being the case, it 

 is of importance to farmers to know how far the application of nitrate of 

 soda is to be recommended. 



If nitrate of soda were employed alone, and year after year, no doubt 

 the land would suffer, although many years might elapse before the evil 

 effects became apparent. It certainly would not improve. If, as is usually 

 the case, the farmer who employs the nitrate is in the habit of applying 

 other fertilisers, such as " town manure," superphosphates, and lime, and 



