CHAPTER 4 



Commercial fertilizers 



A careful study of the condition of farming in the United States shows 

 that the supply of barnyard and stable manure is not adequate to main- 

 tain the fertility of the soil The need for commercial fertilizers is, there- 

 fore, apparent and real, although the amount required in conjunction 

 with natural manures may be comparatively small. 



It is desirable to use commercial fertilizers on many farms and the 

 practice is becoming more general each decade. This is but natural, 

 since there is a constant flow of soil fertility towards the cities. The 

 rapid increase in the city population and the consequent increase in food 

 consumption at those points cause a constantly increasing drain upon the 

 soil fertility of the farms. 



Object and Use of Commercial Fertilizers. — The object of manuring 

 the soil, whether with stable manure, green manure or commercial fertil- 

 izers, is to increase its crop-yielding capacity. In order to justify the 

 practice the resulting increase in products must be more than sufficient 

 to offset the cost of manures or fertilizers applied. This increase need 

 not necessarily be secured the first year after the application, but should 

 be secured in the current and succeeding crops, and should give a net 

 profit on the capital and labor so expended. 



The first noteworthy use of commercial fertilizers in the United States 

 was in 1848. In that year there was imported 1000 tons of guano. This 

 was followed the succeeding year by twenty times that quantity. From 

 that date the importation steadily increased until 1880, when it reached 

 its maximum and began to decline because of a failing supply of guano. 

 Other materials, such as sodium nitrate from Chile and the potash salts 

 from Germany, have taken the place of the guano. These, together with 

 the development of our phosphate mines, the use of cottonseed meal and 

 the utilization of slaughter-house by-products, have met the continually 

 increasing demand for commercial fertilizers by our farmers. According 

 to census reports, the expenditures for fertilizers in the United States 

 during the past four census-taking years have been as follows: 



Year. Value. 



1879 $28,500,000.00 



1889 38,500,000 . 00 



1899 54,750,000 . 00 



1909 112,000,000 . 00 



There seems to be little doubt but that this rate of increase in the 

 use of fertilizers will continue for some time to come. The subject is one 



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