344 
MESSRS. J. B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
manure, doubtless owing to a deficiency of nitrogen available to sucb plants as were 
developed. But when the ammonia-salts were used alone, there was obviously, on 
the other hand, a deficiency of mineral supply for the amount of available nitrogen. 
The superphosphate of lime, supplying as it did, besides a considerable excess of phos¬ 
phoric acid, also an excess of sulphuric acid and lime, and some magnesia, remedied 
this so far; but, as will be seen from the next comparisons, there was still a consider¬ 
able deficiency of some other mineral constituent, or constituents, necessary to give 
anything like full effect to the amount of nitrogen supplied in the ammonia-salts. 
The figures show that there was, not only much more total produce, but also much 
more nitrogen and total mineral matter annually removed, when the superphosphate as 
well as the ammonia-salts was used ; but that, notwithstanding the different actual 
amounts of yield, there was, under the two conditions of manuring, very nearly the 
same percentage reduction in yield of hay, of nitrogen, and of mineral matter, over 
the last 10 compared with the first seven years. There is thus indicated the influence of 
a larger supply of mineral matter, but at the same time an almost equal rate of decline 
in the amount available as the experiment proceeded. Calculation of the analytical 
results shows, however, that the increase in the amount of total mineral matter 
removed under the influence of the addition of superphosphate was considerably 
greater than was represented by the increased amount taken up of those mineral con¬ 
stituents which it supplied—namely, lime, magnesia, phosphoric acid, and sulphuric 
acid. There was also more potass, in a greater proportion more soda, and more silica, 
taken up—all of which must have been supplied by the soil itself. It has before been 
pointed out that the produce by ammonia-salts alone removed even less potass than 
that without manure—a fact supposed to be explained by the greater root-range of the 
much more varied flora of the unmanured plot; and although the addition of super¬ 
phosphate to the ammonia-salts causes the removal of considerably more potass, there 
is still not much more removed than without manure. There was, too, a very great 
decline in the average annual amount taken up of almost every mineral constituent 
over the second period compared with the first; the exceptions being phosphoric acid 
and magnesia, in which the reduction was much less. Further, whilst in the dry 
substance there was (excepting lime) an abnormally high percentage of the mineral 
constituents supplied, there was an abnormally low percentage of those not supplied— 
again indicating that the point of exhaustion of available supply was reached. With 
this evidence of exhaustion of mineral matter, there was an abnormally high per¬ 
centage of nitrogen in the dry substance of the produce of both plots, but especially 
in that by the ammonia-salts alone. 
With this chemical evidence of repletion of nitrogenous, and deficiency of min eral 
supply, the botanical character of the herbage was equally significant. On both plots 
it became more and more gramineous, and the more so where the superphosphate of 
lime was also used. On both, the Leguminosas nearly disappeared, and, again, the more 
so where the superphosphate of lime was employed. On both, the miscellaneous 
