594 Journal of Agricultural Research voi. x, no. 12 



Somewhat more boric acid was found in the grain and straw grown 

 in 1 91 6 than in that grown in 191 5, while the smallest percentage of 

 boric acid was found in the 191 4 samples. Even after applying borax 

 or colemanite to the same ground for 3 years, very little boron was taken 

 up by the plants grown the third season. A little more boron was 

 absorbed by the plants grown on the plots fertilized with manure con- 

 taining borax than by the plants grown on the plots fertilized with 

 manure to which colemanite had been added. In the pot tests reported 

 by Cook (3) the same tendency for wheat plants grown on soil containing 

 added borax to absorb more boron than plants grown on soil containing 

 added colemanite was observed. The water figures were lower in the 

 grain and higher in the straw each successive year, and there was a 

 marked reduction each year in the ether extract of both wheat and 

 straw from all plots, but an increased nitrogen content. The average 

 figures show a little more water, fat, and nitrogen in the manured-con- 

 trol wheat and straw than in the borax-manure samples of wheat and 

 straw. 



The distribution of the boron between the grain and straw samples tested 

 was nearly equal. In 191 5 the roots of some plants from each plot were 

 tested for boric acid with the following results: Borax plot 0.00007 per 

 cent, colemanite plot 0.00007 P^r cent, and control plot o. 



ANALYSES OF SOIL SAMPLES 



In Table III analyses of samples of soil taken from the various plots 

 are recorded for each of the three years. The methods used for total 

 nitrogen and ammonia (magnesium-oxid distillation process) were those 

 of the Association of Official Agricultural Chemists.^ The aeration 

 method as outlined by Folin and Macallum (4) for the determination of 

 ammonia and the nitrate method of the American Public Health Asso- 

 ciation (2) were employed. Both acid soluble and total boric acid were 

 determined in each sample. For soluble boron 50 gm. of soil and 200 

 c. c. of 1-20 hydrochloric acid were shaken for one hour. The filtrate 

 was made alkaline with lime, evaporated to dryness, and ashed. The 

 ash was taken up in hydrochloric acid, diluted to 100 c. c. volume, and 

 aliquots used for the colorimetric estimation of boron. The total boron 

 was estimated by fusion of the soil sample with sodium hydroxid. In 

 both cases the colorimetric method, with strips of curcumin paper, was 

 employed for estimating the boron. It is apparent that the boron in the 

 soil is combined in some insoluble form, such as a silicate, and can be 

 estimated only by a fusion process. 



1 Wiley, H. W. Op. cit. 



