EXPERIMENTS ON THE MIXED HERBAGE OF PERMANENT MEADOW. 373 
Table XXII. —Estimated Nitrogen supplied in the Manure, recovered in the increase 
of the hay-crop, determined as residue in the soil, and not recovered in either the 
increase or the soil, to the depth of 54 inches. 
Nitrogen of manure. 
Per acre. 
Per cent. 
lbs. 
Supplied in farmyard manure in eiglit years. 
1606 
Recovered in increase in 20 years (over plot 3). 
291 
1ST 
Not recovered in increase.. 
1315 
81'9 
Residue, determined by soda lime, in soil 54 inches deep . 
529 
32-9 
Not recovered in increase or in soil. 
00 
Ci 
49-0 
In interpreting these figures we have to bear in mind the uncertainty in the estimate 
of the amount of nitrogen supplied in the manure ; the difficulty in determining how 
much of the nitrogen of the produce was derived from that supplied; the possible 
natural difference, apart from the influence of manure, in the soils and subsoils of the 
respective plots; and also the unavoidable range of error in the sampling of, and 
determinations of the nitrogen in, the soils, and the calculation of such data into 
quantities per acre. Indeed, it appears at first sight anomalous, that the manured soil 
should show actually less nitrogen in the fourth, fifth, and sixth depths, than the 
unmanured ; and, although the result may be due to differences in the subsoils them¬ 
selves, irrespectively of the difference of recent treatment, it is at the same time not 
inconceivable that, with the accumulation of manurial matter in the upper layers of the 
manured soil, and the consequent increased luxuriance of the vegetation, more moisture, 
and with it more soluble nitrogenous compounds, might be drawn upwards from the 
lower layers than without manure, and in that case the mode of estimate adopted 
above would, so far, be the most correct. But if we take into account the figures 
relating to the first, second, and third, depths only—that is, only so far as the manured 
soil shows more nitrogen than the unmanured—the results as to accumulation and loss 
of nitrogen will stand as follows 
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