THE BROADBALK WHEAT SOILS. 
39 
Obviously there is no such difference here as to account satisfac- 
torily for the disappearance; indeed, the subsoil of one of the unma- 
nured plats is actually richer than that of the manured plat, and if 
We brave] into the third depth we find that all three are practically 
alike. 
Although formidable difficulties arc placed in the way of quanti- 
tative acreage deductions from the subsoil analyses, owing to the 
natural irregularities of the subsoil to which I have already alluded, 
wc arc nevertheless able at once to draw from the figures a rough 
deduction that the organic matter supplied to the land in the form of 
farmyard dung, even if some of it becomes bodily transferred to 
the subsoil by the agency of worms or insects or by any other means, 
does not materially affect the permanent nitrogen contents of the 
subsoil. There Beems, from the carbon results, to be sonic evidence 
of increase of organic matter in the upper subsoil beyond what is 
probably attributable to root residue; but, if this is so. it is organic 
matter so far decomposed that its nitrogen does not seem to have 
been conserved. 
THE TWO DUNGED PLATS (2a AND 2b). 
As a further illustration of this we may compare the soils and sub- 
soils of plats -a and 2b, the former of which had been dunged for only 
nine years and the latter for fifty years, the nitrogen supply in the 
former case being estimated at 1, son pounds only and in the latter 
case at K>, <><)<> pounds. 
TABLE \d.—llr<><t<lh<ilh- wheat soils ( rsr>.;), j>lnfs .'a <tn<1 :h. 
Plat 2a, dunged u tie years: 
First 9 inches 
Second 9 inches 
Third 9 inches 
Plat 21>, dunged fifty years: 
First !• inches 
Second 9 inches 
Third !t inches •. 
It is clear, therefore, that, in spite of the notable surface accumula- 
tion, but little of tin' large quantities of nitrogen supplied in dung 
and not returned in crops is to be found in the subsoil. The greater 
pari of it has disappeared, either as nitrates in the drainage, or per- 
haps, and probably largely, by fermentative processes yielding free 
nitrogen. The question of drainage will have to be discussed here- 
after; for the moment we are only concerned with the converse ques- 
tion of accumulation. 
Nitrogen. 
Per cent. 
0811 
,0880 
.2207 
07U7 
.(Hi.-*", 
Pounds 
per acre. 
4. us? 
2. W, 
1. N42 
5. 151 
2. mil 
1,881 
Carbon. 
Per cent. 
Pounds 
per acre. 
1.582 
.045 
. 515 
2.230 
.7+8 
.492 
:».7li 
17,230 
14,370 
52,046 
19.981 
la, 734 
