Food foe. Plants. 149 



26. Nitrate, and ammonium sulphate showed practi- 

 cally no residual effect. Dried blood showed a slight 

 residual effect. 



27. The animal manures showed a very pronounced 

 residual eifect. 



28. Notwithstanding the annually repeated applica- 

 tions of manure, together with relatively large amounts 

 of nitrate, there is no marked evidence of denitrification. 



29. All of tlie cylinder soils lost considerable quanti- 

 ties of nitrogen. 



TWENTY YEARS' WORK ON THE AVAILABILITY OF 

 NITROGEN IN NITRATE OF SODA, AMMONIUM 

 SULFATE, DRIED BLOOD AND FARM MANURES. 



J. G. LiPMAN and A. W. Blair, Netv Jersey Agricultural Experiment 



Station. 



(Reprinted from " Soil Science.") 



During the last twenty-five years the fertilizer indus- 

 try 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 numl)er 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 nitro- 

 genous materials which, under normal conditions, form 

 the most expensive part of the fertilizer. 



The movement to save these waste materials contain- 

 ing nitrogen came none too early, for it was the deple- 

 tion in the soil of this element that was largely respon- 

 sible for the run-do^\m 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 its roots may reach out for the 



