BULLETIN OF THE 



No. 37. 



ContribuHon from the Bureau of Soils, Milton Whitney, Chief. 

 December 8, 1913. 



NITROGENOUS FERTILIZERS OBTAINABLE IN THE UNITED 



STATES. 



By 



J. W. TlTRRENTINE, 



Scientist in Soil Laboratory Investigations. 

 INTRODUCTION. 



Present agricultural practice requires that nitrogenous matter be 

 supplied to the soil supporting crop growth. At one time it was the 

 belief that all the nitrogen found in the substance of the plant had its 

 origin in that added to the soil as a fertilizer. Now, however, it is 

 definitely known that this is by no means true in the case of certain 

 types of plants and that the uncombined nitrogen of the atmosphere 

 is made available for plant metabolism through the instrumentality 

 of lower organisms inhabiting the soil. The marked accumulation 

 of nitrates in certain soils of Colorado has been explained on the basis 

 of the bacterial fixation of atmospheric nitrogen. 1 Nitrogen com- 

 bined as nitrate of soda occurs naturally in the arid plateau region 

 of Chile. It also occurs in certain of the rainless portions of the 

 United States. In this country, however, it occurs as so small a 

 proportion of its carrier that its extraction therefrom under present 

 conditions is commercially impracticable. 2 Aside from this occur- 

 rence, combined nitrogen is found in nature only in the complex 

 compounds constituting the organisms of plants and animals or 

 arising from the decomposition of these. In small amounts it is found 

 in the soil in the form of certain organic compounds, 3 some of which 

 are toxic in their action on growing plants, and some beneficial. 



The nitrogenous compounds comprising animal and vegetable 

 tissues constitute the principal foods for man and animals. In gen- 

 eral it is true, therefore, that only in those instances where their 

 occurrence is such as to preclude their ready marketing or where por- 

 tions of them for one reason or another are unfit for food, are they 



i Headden, Colo., Agr. Expt. Sta., Bulls. Nos. 155 and 160. 



2 Free, Report of a Reconnoissance of the Lyon Nitrate Prospect near Queen, New Mexico, Circ. No. 62 

 Bureau of Soils, U. S. Dept. Agr.; Gale, TJ. S. Geol. Survey, Bull. 523, 1912. 



3 Bulls. Nos. 53, 70, 74, 77. 83, 87, Bureau of Soils, U. S. Dept. of Agr. 



14155°— 13 



