338 
MESSRS. J. B. LA WES AND J. H. GILBERT OR THE RESULTS OF 
It has been before observed that, with an increased amount of soda applied in the 
manure, more was taken up and retained—a result which would be more marked in 
the case of imperfectly ripened vegetable matter, like hay, than in that of fully 
ripened products, such as cereal grain. It has also been observed that when there 
was an increased fixation of silica, it was generally in association with an increased 
amount of soda rather than of potass taken up. It w r as strikingly so in the case of 
the produce of plot 14. Thus, besides the much greater accumulation of soda which 
was so liberally applied, the plants growing under the influence of the nitrate accumu¬ 
lated not only more of each of the other mineral constituents (except potass) which 
were equally supplied to both plots, but more also of silica which was not supplied to 
either. This obviously indicates possession by the roots of the growing herbage of a 
greater range of soil and subsoil, and is consistent with the facts which have been 
pointed out as to the character of the root development, and the altered condition of 
the subsoil, under the influence of the nitrate of soda. 
Since the produce grown by the mineral manures and nitrate was riper when cut 
than that by the mineral manures and ammonia-salts, a somewhat lower percentage in 
the dry substance, of potass, as well as of other constituents, would be expected; and 
it might merely indicate a greater accumulation of organic matter at the maturing 
period, by which, obviously, the percentage in the dry substance of the already 
accumulated mineral matter would be reduced. Such reduction is known to be the 
general accompaniment of favourable maturation. But here, the percentage of potass 
in the dry substance of the produce grown by the nitrate was, taking the average of 
the 18 years, only about four-fifths as much as in that grown by the ammonia-salts. 
This reduction is probably greater than can be accounted for merely by a greater 
accumulation of organic matter during the maturing period. Indeed, there was, not 
only a lower percentage, but, as already mentioned, a notably less actual amount per 
acre, of potass fixed under the influence of the nitrate, though it was equally supplied 
to both plots, and though the herbage was even more gramineous, and more stemmy— 
a result which is certainly somewhat remarkable. And although there was at the same 
time much more soda taken up, and the excess was more than equivalent to the actual 
deficiency of potass per acre, it was not sufficient to compensate for the deficiency of 
potass per cent, in the dry substance. 
In connexion with these results, showing a greater amount of produce by the use of 
a given amount of nitrogen as nitrate of soda than as ammonia-salts, an increasing 
instead of a decreasing produce in the later years, a greater independence of drought, 
and a greater disintegration, increasing the porosity of the clay subsoil, it may be well 
to refer to some results obtained in experiments with barley. In the field at Rot- 
hamsted which is now (1879) growing the twenty-eighth crop of barley in succession, 
two plots received, in the first season, equal amounts of mineral manure ; but in the 
second, third, fourth, fifth, and sixth years, the one received 550 lbs., and the other 
275 lbs., of nitrate of soda per acre per annum. From that time up to the present, each 
