.Sail Fertility 81 



commercial fertilizers are derived from mines, from by-products 

 of manufacture, from meat-packing houses, and from the arti- 

 ficial fixation of atmospheric nitrogen. A large quantity is 

 used annually. The census reports show that in 1909 approxi- 

 mately $112,000,000 was spent by the farmers of the United 

 States for commercial fertilizers and this expenditure is increas- 

 ing rapidly. For example, in 1889, the sum of $28,000,000 

 was spent and $55,000,000 in 1899. In 1909, about half of 

 the commercial fertilizer purchased was used in the South 





No fertilizer. Complete fertilizer. 



FIG. 29. Effect of commercial fertilizer at Rhode Island Experiment Station. 



Atlantic States; about half of the remainder was sold in the 

 Middle Atlantic and the New England States and only about 

 5 per cent was used by farmers west of the Mississippi. The 

 western lands, since they have been farmed a comparatively 

 short time, require less fertilizer than those in the East and 

 South. Effects of commercial fertilizer in crop growth are 

 shown in Fig. 29. Several miscellaneous crops were planted 

 on two plots, one with no fertilizer and one with complete 

 fertilizer. Notice the difference in plant growth. 



Although commercial fertilizer has an important use in the 

 agriculture of this country, it is possible to misuse it. It is 

 rather expensive, except for certain special crops, and usually 

 does not add humus to the soil. The use of fertilizer alone 



