FERTILIZERS 13D 



and 12 per cent of available phosphoric acid. By applying 

 from 250 to 500 pounds of this commercial fertilizer per acre 

 the best general results are obtained. If land has been quite 

 exhausted by continuous wheat growing, the proportion of ni- 

 trogen and potash should be greater. Commercial fertilizers 

 are best applied by means of an apparatus made for this pur- 

 pose and attached to the wheat drill. They may also be broad- 

 cast just in front of the drill. In the. case of winter wheat, 

 most of the nitrogen is often applied early in the spring so as 

 to prevent loss through drainage during the winter. 



THE COMBINED GRAIN AND COMMERCIAL FERTILIZER DRILL 



Kinds of Fertilizers. These naturally fall into two classes, 

 barnyard manure and commercial fertilizers. It is only on 

 farms where the supply of manure is not adequate to preserve 

 a high state of soil fertility that commercial fertilizers are 

 economical. In general farming the former has the greatest 

 relative value on account of individual or combined physical, 

 chemical and bacterial influences not yet fully understood. Con- 

 sidering equal weights, however, most commercial fertilizers con- 

 tain more plant food than manure does. It is also claimed that 

 when applied to wheat they will produce larger returns. Never- 

 theless, the lower cost of farm manure always makes its use 

 more profitable than that of other fertilizers. Where both are 



