THE BBOADBALK WHEAT -oils. 
47 
On plat 8, where a still larger quantity of ammonium salts is used, 
and where the increase of crop is much less, there does not appear to 
be any further accumulation of nitrogen as far as the first inches 
are concerned. 
If, however, we take the second and third depths into account, we 
certainly find considerably larger accumulations in plat S than in 
plat 7. Indeed, the proportion between the excess of crop and the 
excess of nitrogen accumulated in the case of plat 8 agrees more 
nearly with that of plat 5 than does the proportion in the case of plat 
7. The following further table shows the results found in 27 inches 
of soil : 
Table 2±. — f>ro<t<lh<tlk wheat soils. !S!>.;— Plats ?, ami S further compared. 
[ First -'T laches. | 
Nitrogen 
1>«t a- r»- 
added 
iinmuilly 
in am- 
monium 
Excels of 
crop per 
acre as 
compared 
with plat S 
Excess of 
nitoffM 
per a«-r«- in 
first T, 
inches as 
compared 
with plat .">. 
Excess of 
carl>on 
per acre in 
tirst-*7 
inches as 
compared 
with plat Sl 
Pounds. 
Pmtnds. 
Pounds. 
Pounds. 
43 
1,600 
US 
1,701 
Plat 7 
m 
8,807 
818 
£ 
un 
415 
5,H44 
Whether we take the first '.» inches only or the first '27 inches, the 
increase in organic carbon Is greater as the supply of nitrogen and t he 
growth of crops have been greater, though aot in direct proportion, 
the low percentage of carbon in the samples representing the second 
and third depths of plat 7 disturbing an otherwise reasonably close 
concordance in the proportion of crop Increase and of increase in 
residual carbon. But once again it must be remembered that the 
subsoil irregularities prevent a too close reasoning upon 1 he figures 
yielded by their analyses for total nitrogen and total carbon. 
In fact, the irregularit ies of the subsoils leave us unable, from direct 
evidence, to decide whet her or not the natural subsoil nitrogen either 
diminishes by contributing to plant food on the one hand, or is aug- 
mented by crop residue on t he ot her, so far as the continuously cropped- 
wheat land is concerned. 
PLATS 10a, 11, 13, AND 7 (ALL RECEIVING LIKE DRESSINGS OF 
AMMONIUM SALTS, BUT DIFFERING IN MINERAL TREATMENT). 
Before passing on, I must, at t ho risk of being tedious, direct spe- 
cific attention to \vt another combination of plats, viz, 10a, 11, 13, 
and 7. The members of the series we have just been discussing were 
all alike in being fully manured with phosphates and potassium, 
sodium, and magnesium salts, differing only in their nitrogenous treat- 
ment. Now, the following plats are alike in that they have all for 
