336 
MESSRS. J. B. LA WES AND J. H. GILBERT ON THE RESULTS OF 
showed slightly the least, and the lowest or sixth depth the most, of the bright 
clay tinge. 
In the soil of the plot manured with the mineral manure and ammonia-salts the 
roots did not appear to penetrate much deeper than in that of the unmanured, but 
they were in greater quantity and of larger size. The first nine inches of soil was 
perhaps rather darker, and more mould-like; the second nme inches was decidedly more 
changed by vegetation than that of the unmanured plot, and the third and fourth 
were slightly so. The fifth and sixth were little distinguishable in colour from the 
raw reddish-yellow clay of the unmanured plot at corresponding depths. 
The first and second nine inches of the soil of the nitrate-plot showed but little 
difference compared with those manured with ammonia-salts. The third, fourth, 
fifth, and sixth nine inches were, however, very different in appearance from the 
corresponding layers of either of the other plots, the clay being much mottled or 
veined, and when the samples were powdered they were of a yellowish-grey instead 
of reddish-yellow colour, and the lighter or less red the greater the depth. In the 
samples taken in 1876 the distinctions were by no means so marked; but still the 
subsoils of the nitrate-plot showed in the second, third, fourth, and fifth depths, a 
lighter, yellower, and less red tinge. 
The percentage of nitrogen in the different soils, at the different depths, will be 
recorded and considered in detail further on ; but it will be of interest briefly to 
notice the general bearing of the results in this place. Although the percentages 
(determined by soda lime) in the samples collected after a lengthened continuance of 
the drought in 1870 differ in some respects from those on the samples of 1876, the 
two series agree in showing, at every depth, a higher percentage on the ammonia- 
plot than on the unmanured, and, with one slight exception which may be accidental, 
a lower percentage in the soils of the nitrate than in those of the ammonia-plot, 
especially in the lower layers, where it is lower also than in the case of the unmanured 
plot, and indeed than in that of the majority of the other plots. 
That the upper layers of the soil of the ammonia-plot should show higher percentages 
of nitrogen than those of either of the other plots is consistent with the fact that the 
nitrogen of ammonia-salts is, in the first instance, in a great degree arrested in the 
upper layers of the soil, and is so, much more than is that of nitrate of soda ; and that 
the percentage should be also higher in the lower depths than without manure indi¬ 
cates, presumably, a gradual percolation of the supplied nitrogen in some form. With 
the rapidly distributing nitrate of soda, and with it the more deeply penetrating roots, 
there is, on the other hand, a less accumulation of nitrogen, not only in the upper but 
in the low T er layers; and that the percentage should decrease so rapidly in the lower 
layers is probably partly due to passage upwards in dry, and, in greater measure, 
drainage downwards in wet, weather. Thus, it has been shown that in the drought 
more water passed upwards from the lower layers, and it would doubtless carry with 
it nitrate in solution ; and with the greater solubility of the nitrate, and the greater 
