JOfflAL OF AGEETIIAL ISEARCH 



Vol. X Washington, D. C, September 17, 1917 No. 12 



EFFECT OF THREE ANNUAL APPLICATIONS OF BORON 



ON WHEAT 



By F. e. Cook, Physiological Chemist, and J. B. Wilson, Assistant Chemist, Bureau 

 of Chemistry, United States Department of Agriculture 



INTRODUCTION 



The object of these experiments was to determine whether or not 

 boron when applied to horse manure in quantities sufficient to act as a 

 fly larvicide would have a cumulative action detrimental to wheat 

 (Triiicum spp.) grown on soil fertilized with this manure for three con- 

 secutive years. 



EXPERIMENTAL WORK 



Four plots of one-twentieth of an acre each on the farm of the Bureau 

 of Plant Industry at Arlington, Virginia, were used for the experiments. 

 One plot was used as a manured control and a second as an unmanured 

 control. The third plot received manure plus borax, and the fourth 

 manure plus colemanite. The manure was applied to all plots at the rate 

 of 20 tons per acre, and the same variety of winter wheat was planted each 

 year on all the plots. Borax was mixed with the manure the first year, 

 (1913), at the rate of 0.33 pound per bushel. The last two years (1914 

 and 191 5) the borax v/as mixed with the manure at the rate of 0.08 pound 

 per bushel, and the colemanite was mixed with a second pile of manure 

 at the rate of 0.095 pound per bushel. 



It was calculated that when borax was mixed with manure at the rate 

 of 0.08 pound per bushel and the manure applied at the rate of 20 tons 

 per acre an equivalent of 0.0022 per cent boric acid (H3BO3) was present 

 in the upper 6 inches of the soil. In the same way it was calculated for 

 the colemanite plot that an equivalent of 0.0029 P^^^ cent of boric acid 

 was present in the upper 6 inches of soil. The amount of borax added 

 the first year, 0.33 pound per bushel, furnished 0.0088 per cent of boric 

 acid to the upper 6 inches of soil. 



The above figures show that the boron was applied as follows: The 

 borax plot received boron the first year at the rate of 154 pounds of boric 

 acid per acre and the second and third years at the rate of 38.5 pounds 

 per acre. The colemanite plots received boron at the rate of 50.75 

 pounds of boric acid per acre each year. 



Journal of Agricultural Research, Vol. X, No. 12 



Washington, D. C. Sept. 17, 191 7 



is Key No. E— 6 



(591) 



