EXPERIMENTS ON THE MIXED HERBAGE OF PERMANENT MEADOW. 381 
quantity estimated to be supplied was contained in the total produce, whilst the 
increased yield represented 33 per cent. The residue of the phosphoric acid, like that 
of the potass, is very little subject to loss by drainage. 
Of sulphuric acid, there is a much less increased amount found in the ash of the 
crop, in proportion to that estimated to be supplied, than of phosphoric acid. 
Of chlorine, the increased amount found in the produce is, during the years of the 
application of the manure, greater in proportion to the estimated supply than that of 
any other constituent; but the proportion diminishes more rapidly in the subsequent 
years than that of any other constituent. Both chlorine and sulphuric acid are very 
subject to loss by drainage. 
Lastly, of silica, the produce of the 20 years contained about 41^- per cent, as much 
as there was estimated to be supplied of soluble silica in the dung, and the increased 
yield of it represented about 22 per cent. 
Thus, of the three more important constituents of manure, nitrogen, potass, and 
phosphoric acid, when these are supplied in farmyard manure, the nitrogen is reco¬ 
vered in the least proportion in the increase of the crop for which it is applied; it 
leaves a large determinable residue within the soil, which, however, is very slowly 
available to succeeding crops; and, finally, it is subject to serious loss by drainage, 
and probably by evolution into the atmosphere also. The potass, so supplied, is reco¬ 
vered in increase in much greater proportion during the years of the application; in 
much greater, though still rapidly decreasing, proportion, in subsequent years, and is 
very little subject to loss by drainage. The phosphoric acid, again, is recovered in 
much greater proportion than the nitrogen, but not in so large a proportion as the 
potass; it too, like the potass, is but little subject to loss by drainage. 
The much less immediate effect of a given amount of nitrogen when supplied in 
farmyard manure than when in ammonia-salts or nitrate of soda, the consequent 
necessity to supply so much more in that form to obtain a given result, and .the very 
slow action of the remaining residue, are important elements in the scientific explana¬ 
tion of the practically recognised much lower money value of a given amount of 
nitrogen so supplied. 
It remains to point out the difference of effect when, besides the farmyard manure, 
200 lbs. of ammonia-salts were also annually applied per acre, both over the eight 
years of the application of the dung, and over the next 12 years of the action of the 
residue. As already explained, plot 1 was devoted to this experiment. 
Under the influence of the addition of the ammonia-salts, the ffrowinof herbao’e 
acquired a darker green colour; gramineous species became more, and both leguminous 
and miscellaneous species less prominent, than either on the unmanured plot or that 
with the farmyard manure alone. Compared with the latter, in the early years, Poa 
trivialis, and Bromus mollis , were even more prominent, as also was Dactylis glomerata; 
