UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1180 
Washington, D. C. T January 22, 1924 
FIELD EXPERIMENTS WITH ATMOSPHERIC-NITROGEN FERTILIZERS. 1 
By F. E. Allison and J. M. Braham, of the Fixed-Nitrogen Research Laboratory, and 
J. E. McMurtrey, jr., of the Bureau of Plant Industry. 
CONTENTS. 
Page. 
Introduction 1 
Fertilizers used 2 
Soils and crops 5 
Methods used in experiments 5 
Observations during growth 6 
Cyanamid 7 
Ammonium nitrate, double salt, and 
mixed salts 8 
Ammonium phosphate and ammoniated 
superphosphate 9 
Observations during growth— Continued. 
Ammonium chlorid 9 
Urea 9 
TJrephos 10 
Experimental results 10 
Experiments of 1919 10 
Experiments of 1920 and 1921 18 
Review of the results 39 
Summary .• 41 
INTRODUCTION. 
Nitrogen compounds made from the air are rapidly becoming im- 
portant in meeting the world's constantly increasing demand for 
nitrogen fertilizers. A number of European countries are already 
manufacturing sufficient atmospheric-nitrogen fertilizer to meet the 
larger part of their requirements. The United States has made a 
beginning in this direction but still depends almost wholly for her 
nitrogen upon the natural sodium-nitrate deposits of Chile, the 
ammonium sulphate obtained from by-product coke ovens, and the 
various organic sources, such as slaughterhouse wastes, cottonseed 
meal, and fish scrap. A small quantity of cyanamid, 2 imported from 
Canada, is also used. 
Interest in the production of synthetic nitrogen compounds in the 
United States was greatly stimulated during the World War in con- 
nection with the production of explosives. Nitrogen-fixation activi- 
1 The experimental work described in this bulletin was carried out by the Nitrate Division of the Ord- 
nance Office, United States Department of War, working in cooperation with the Bureau of Plant Industry 
of the United States Department of Agriculture. The work during the first year was under the direct 
supervision of the bureau mentioned. During the two following years the work was conducted by the 
Fixed- Nitrogen Research Laboratory, which was a part of the Nitrate Division until its transfer to the 
Department of Agriculture on July 1, 1921. The writers are indebted to Drs. Karl F. Kellerman, W. W. 
Garner, Oswald Schreiner, and J. J. Skinner, of the Bureau of Plant Industry, for many valuable sugges- 
tions in planning this investigation and to members of the staff of the Nitrate Division; particularly Lieut. 
Cols. J. K. Clement and Hardee Chambliss, for assistance in carrying out these experiments. The Office 
of Soil- Fertility Investigations, Bureau of Plant Industry, is conducting field experiments with most of 
the nitrogen materials mentioned in this bulletin. These experiments have been in progress in several 
States for a number of years, and the results are to appear in a later publication. 
2 Crude calcium cyanamid treated with a small quantity of water and of oil. 
•52765°— 24— Bull. 1180 1 
