Sept. 17. 1917 Effect of Applications of Boron on Wheat 



595 



Table III. — Analyses of samples of soil taken 8 inches deep from wheat plots at Arling- 

 ton, Va., fertilized for three consecutive years with manure treated with borax and cole- 

 manite 



There is considerable variation in the total nitrogen results, undoubt- 

 edly due to the sampling. The nitrogen as ammonia, by the magnesium- 

 oxid method, showed a gradual increase in all samples from 1914 to 191 6. 

 The ammonia results by the Folin aeration method were higher in the 

 1 91 5 samples, where the highest total nitrogen results were obtained, than 

 in the 191 6 samples. The soil to which either borax or colemanite was 

 added showed less nitrate nitrogen than the control samples for the years 

 1915 and 1916, while the borax-plot sample showed more nitrates than 

 the control in 191 4. The only sample that showed any boric acid soluble 

 in weak hydrochloric acid was from the borax plot in 191 4, following the 

 very heavy application of borax that year. This plot showed a distinct 

 injury to the wheat the same year. The results for total boric acid showed 

 that considerably more boron was present in the soil to which boron had 

 been added, either as borax or colemanite, than in the control soil; but 

 no evidence of a cumulative action in the soil was found. 



The colemanite plots showed more total boric acid than the borax plots. 

 This is not surprising, in view of the fact that more total boron was added 

 to the colemanite than to the borax plots. 



BORON AND PLANT INJURY 



Nakamura (5) tested the effect of borax on barley grown in pot cultures. 

 He found that amounts of borax equivalent to 0.00 1 per cent of boric 

 acid were toxic and that amounts of borax equivalent to 0.0002 per 

 cent of boric acid produced slight injury. 



