TWENTY YEARS* WORK ON THE AVAILABIL- 

 ITY OF NITROGEN IN NITRATE OF SODA, 

 AMMONIUM SULPHATE, DRIED BLOOD 

 AND FARM MANURES. 



J. G. Lipman and A. W. Blair, New Jersey Agricultural 

 Experiment Station. 



(Reprinted from "Soil Science.") 



During the last twenty-five years the fertilizer 

 industry in the United States has developed rapidly. 

 From a comparatively small tonnage in the early 

 nineties it has grown to more than 7,000,000 tons in 

 1917. 



As the industry has grown the number of materials 

 that go to make up the fertilizers has also increased 

 greatly. Many by-products that were formerly 

 allowed to go to waste are now carefully saved and 

 worked up in the fertilizer factory. This is especially 

 true of the nitrogenous materials which, under nor- 

 mal conditions, form the most expensive part of the 

 fertilizer. 



The movement to save these waste materials con- 

 taining nitrogen came none too early, for it was the 

 depletion in the soil of this element that was largely 

 responsible for the run-down and abandoned farms 

 in the older sections of the United States. For this 

 element, most crops show a quicker response than 

 for any other, and conversely, a falling off in yield 

 will come sooner with a deficiency of nitrogen than 

 of any other element. A supply of available nitrogen 

 aids the plant in getting a good start so that its leaves 

 may begin early to elaborate food from the air and 



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