14 



interest, as indicating the large amounts of nitrogen they 

 contain ; but owing to the great variation in the natural 

 character of the subsoil of one and the same plot at 

 different places, and even at closely contiguous spots, 

 the results are quite inapplicable for comparative 

 acreage calculations, either between plot and plot, or 

 the same plot at different periods, and they have there- 

 fore not been published in detail. This great natural 

 irregularity was very marked in the samples above 

 referred to, but it was still more so in the case of some 

 samples taken in 1887 from 3 plots in the same field to 

 the depth of 12 times 9 inches, = 108 inches, or 9 feet, 

 in all; and it has also been very marked in samples 

 taken to a great depth in other fields, as will be referred 

 to further on. 



But, notwithstanding this difficulty, the results re- 

 lating to what may be called the migratory constituents 

 of subsoils, the nitric acid for example, are of great 

 interest and significance. On this ground alone, it is 

 extremely desirable that each of the wheat field plots 

 should be sampled before long say after the removal 

 of the fiftieth successive crop, to a considerable depth ; 

 certainly not less than to 8 times 9 inches, and perhaps 

 to 12 times 9, as has been done in some of the other fields. 

 If, however, the change in the harvesting and sampling 

 which has been above suggested, be adopted after the 

 removal of the crop of 1891, it would be desirable 

 that the soil-sampling should be undertaken after the 

 harvest of that year. 



But, independently of determinations of nitric acid, 

 chlorine, &c., and notwithstanding the impossibility, 

 arising from natural irregularity in the character of the 

 subsoils, of judging from determinations of the total 

 nitrogen in them, of the degree in which the subsoils 

 of the different plots, or of the same plot at different 

 periods, have yielded up (or acquired), nitrogen, it is of 

 great importance that samples should in future, as in 

 the past, be carefully taken, and preserved ; in the hope 

 that, in the course of time, lines of investigation may 

 be determined upon, which will show the difference, if 



