324 
MESSRS. J. B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
seen further on, when the same mineral manures were used with an increased amount 
of ammonia-salts, a larger amount of every one of the mineral constituents, excepting 
lime, was taken up ; and of this, very much more was annually supplied than was taken 
up. Nor can the falling off be attributed wholly to less favourable seasons during the 
second 10 years ; for, as the next illustrations will show, some other combinations of 
manure yielded more hay, containing more nitrogen, and more mineral matter, over 
the second period than over the first. It should perhaps be noted that one end of the 
plot was apparently to the eye to some extent injured by the roots of a large tree, and 
this injury was the greater in the later years. 
The actual falling off in the amount of mineral constituents taken up over the 
second period was considerable, and it was pretty equal in the soda, the chlorine, 
the lime, and the sulphuric acid; it was about twice as great in the silica, but very 
slight indeed in either the potass or the phosphoric acid. The decreasing amount of 
soda, chlorine, and sulphuric acid, taken up and retained, with at the same time an all 
but maintained assimilation of potass and phosphoric acid, would indicate increased 
tendency to stem and seed formation, and to maturation ; whilst, the deficiency of lime, 
and of silica, is also consistent with a less amount of leaf and greater amount of stem. 
In fact, the percentage in the dry matter—of lime, magnesia, soda, sulphuric acid, and 
silica, was lower than in the produce either without manure or with the ammonia- 
salts alone; whilst that of the potass was nearly twice as high as without manure, and 
more than twice as high as with the ammonia-salts alone, and that of the phosphoric acid 
was also very much higher than either without manure, or with ammonia-salts alone. 
The probability is, that the reduced assimilation of both nitrogen and most of the 
mineral constituents over the second period was less connected with any real deficiency 
of either within the soil, in a condition capable of being yielded up, than with the 
description of plants favoured, and the character both of their underground and their 
aboveground development, with which would vary, not only the range and power of 
collection from the resources of the soil, but also the requirement for this or that 
individual constituent. And it is probable that, in addition to these conditions 
affecting the whole plot, some of the reduced assimilation is to be explained by 
the action of the tree-roots above referred to. 
8. 400 lbs. Ammonia-Scilts, with Mixed Mineral Manure containing Potass, and 
2000 lbs. cut Wdieat Straw; Plot 13. 
Table X. shows the results obtained over the same 10, 10, and 20 years, on plot 13, 
with the same quantity of ammonia-salts, and the same description and amount of 
mineral manure, applied every year, as on the last plot considered (9), but with 2000 lbs. 
of cut wheat straw per acre per annum in addition. The chief object of the application 
of the straw-chaff was to supply silica, and carbonaceous organic matter, somewhat in 
the same condition as they are provided in dung. It obviously also provides some 
