CHAPTER VII 

 COMMERCIAL FERTILIZERS 



It is neither possible nor necessary for all farmers to engage 

 in stock raising or dairying in order to maintain the fertility of 

 the land. While it is possible, as has been described, to main- 

 tain without the purchase of commercial fertilizers, a positive 

 balance of plant food on the farm in the practice of the above 

 systems, it is manifestly impossible to do so in a system of grain 

 farming where the crops raised are all sold from the farm. In 

 the latter system recourse to commercial fertilizers, supplemented 

 by green manuring for the purpose of maintaining the humus 

 content of the soil, must be made sooner or later. 



At the present time probably $60,000,000 are spent annually 

 in the purchase of fertilizers in the United States, and it is no 

 exaggeration to say that fully one-half of this is money thrown 

 away. This is not an argument against their use, but simply 

 means that they should be purchased with judgment and not 

 used at all until actual investigation has shown them to be 

 necessary. 



Plant food not the only factor in crop growth. It should be 

 remembered that other factors than plant-food supply enter into 

 the production of large crops. Improper physical condition of 

 the soil, lack of moisture, deficiency of humus, unsuitable soil 

 reaction, unfavorable weather, etc., all may interfere with the 

 normal and vigorous development of the plant and thus cause 

 diminished crop returns, even when the plant has within reach 

 all the food it needs. These unfavorable conditions may partly 

 be ameliorated through means available to man, such as drain- 

 ing, irrigating, harrowing, liming, etc. Too frequently fertil- 

 izers are made to take the place of tillage when they should be 

 used to supplement it. That is, fertilizers are more likely to 

 give profitable results when used in conjunction with an excel- 



