288 



DRY FARMING 



may carry. It is possible that on some soils the use of 

 one or more of these fertilizers might pay even now, but 

 in the few tests that have been conducted (usually on 

 good soils) they have not produced sufficient increase to 

 warrant their use, except perhaps in truck farming or 

 potato growing. The time will come, no doubt, when it 



Fig. 96. — ^Wheat Field at Fort Vermilion, Peace Eivor. 

 700 miles by trail north-west of Edmonton, Alta. 



will be necessary to apply phosphorus, the supply of 

 which in our soils is not high; and we are shipping it 

 away in large quantities in the grain we sell. 



Nitrogen can be gotten from the air by growing 

 legumes, and the potash supply in the soil is very high, 

 but unfortunately there is no means of replenishing 

 the phosphorus supply except by purchasing. It is in- 

 teresting to note that the use of phosphate fertilizers in 

 some places results in an earlier crop of grain. 



