466 Journal of A gricultural Research voi. xiii, no. 9 



borax-treated plot than on the 16- or 24-ton plots. The amounts of boric 

 acid found in the heads from the colemanite-manure plots were practically 

 the same in the three cases. Small quantities of boric acid were found 

 in the heads from all three of the control plots. 



Similar determinations are given for the straw taken from all of the 

 plots. The moisture results are very uniform for the nine samples, while 

 the fat figures are a little higher for the three control samples than where 

 boron was added to the soil. The nitrogen results show a marked in- 

 crease, varying directly with the amounts of manure applied to the soil. 

 The results for boric acid show that the rye took up the boron from the 

 different plots in proportion to the quantities of boron added to the soil. 

 On the other hand, the form in which the boron was added had a decided 

 influence on the amounts absorbed by the plants, over twice as much 

 boron of the readily soluble borax being absorbed by the plants as when 

 the boron was added as the insoluble colemanite (calcium borate). 



The control samples showed the presence of small amounts of boron. 



ANALYSES OF SOIL, BETHESDA, MD., 1914-15 



Samples of soil were taken 6 inches deep from the different treated and 

 untreated plots. The samples were taken three times — that is, just prior 

 to the second and third applications of manure and at the time of harvest- 

 ing the third crop, eight months after the third application of the manure 

 to all plots. The total nitrogen and the volatile nitrogen results obtained 

 on distilling with magnesium oxid (see Table XIII) vary considerably for 

 the different years, but the samples taken from all the plots on the same 

 dates are rather uniform. The results for volatile nitrogen by the Folin 

 aeration method are higher in the samples taken on June i, 191 5, after 

 the first addition of manure to the soil, than in the samples taken on 

 September 3, following the second addition, or in the samples taken on 

 June I, 1 91 6, after the third manure treatment. The reduction in the 

 control samples makes it evident that the boron was not the cause of 

 the decrease. The nitrate results show the same tendency to decrease 

 in each succeeding set of samples from June, 191 5, to June, 1916, as was 

 noted before for ammonia. There is no apparent reduction in either the 

 ammonia or nitrates from the added boron. 



No acid-soluble boric acid was found in any sample. The largest 

 amounts of total boric acid were found in the samples taken on Septem- 

 ber 3, 1 91 5, only two m.onths after the second application of the manure, 

 while with the samples taken on June i, 191 5, and June i, 191 6, seven 

 months had elapsed since the addition of the boron-manure to the soil. 

 No more total boric acid was found in the soil samples taken in June, 

 1 91 6, after the third application of boron-manure than in the samples 

 taken in June, 191 5, following the first application of boron-manure to 

 the plots. In view of this, and also as the most boron was found in the 



