64 
IOWA ACADEMY OP SCIENCES. 
TABLE II. 
PERCENTAGE IN AIR-DRIED SOILS. 
PHOSPHORIC ACID 
POTASH 
P2 
O 5 
K2 
0 
JNITKUHEN. 
SAMPLES. 
Soluble in Soluble in 
Soluble in 
Soluble in 
Soluble in 
HCl 
citric acid 
HOI 
citric acid 
Total. 
citric acid 
A j Best 
.30 
.0118 
.27 
.0039 
- .179 
.0033 
1 Poorest 
.15 
.0235 
.33 
.0060 
.301 
.0150 
T> ( Best 
.18 
.0196 
.33 
.0139 
.378 
^ "l Poorest 
.13 
.0133 
.26 
.0095 
.154 
.0028 
pij Best 
.16 
.0!46 
.34 
.0093 
.336 
.0OS7 
^ ( Poorest 
.15 
.0091 
.34 
■0058 
.109 
.0031 
yj ( Best 
.16 
.0193 
.38 
.0117 
' .345 
.0109 
.22 
.0131 
.30 
.0056 
.235 
.0075 
— i Bp,st 
■ 0H76 
.0139 
.0075 
^ / Poorest 
.0070 
.0037 
.0029 
y ) Best 
.0563 
.0113 
.0092 
^ 1 Poorest 
.0520 
.0046 
.0176 
^ ( Bfist 
.0517 
.0209 
.0134 
/ Poorest 
.0281 
.0141 
.0118 
u i Best 
.0141 
.0056 
.0134 
^ ( Poorest 
.0132 
.0038 
.0124 
j j Bf^st ... 
.0139 
.0048 
0115 
^ i PnnTPcfi . 
.00^3 
.0036 
.0099 
It will be noticed in the results on the first four pair of samples 
where the old and new methods of analysis can be compared, 
that as a rule the differences shown between the best and the 
poorest soils are relatively much greater by the new than by 
the old method. Usually the differences are in the same direc- 
tion, by the two methods; but there appear to be exceptions to 
this, namely, in respect to the phosphoric acid of samples A 
and D. Such a condition might reasonably be expected in com- 
paring a soil originally more fertile, but much worn, with one 
originally less fertile, but little worn. In the cases here recorded 
I can not state the history of the soils. 
It will also be noticed, in comparing the figures obtained by 
the new method for each pair of soils, that in every case there 
is a wide difference in regard to at least one of the three plant nutri- 
ents reported upon — the three in which a soil is most likely to 
be deficient. These wide differences probably, in most of the 
cases, reveal the causes of the observed differences in fertility; 
I say, probably, because the work here reported is purely 
chemical, and little account has been taken of the mechanical 
condition, or physical constitution, of the soils — a factor second 
only to chemical composition in determining fertility. Physical 
