92 BULLETIN 1059, U. S. DEPARTMENT OF AGRICULTURE. 
Table 3. — Wilting coefficients of four species in five types of soil. 
Capillary 
moisture. 
Moisture 
equiva- 
lent 
100-G. 
Mean wilting coefficient. 
Sample No. and description. 
Yellow Lodge- i Douglas 
pine, i pole, < fir. 
English 
spruce. 
590. Sifted granite gravel with loam 
Per cent. 
26.58 
31.85 
35.34 
37.77 
43.16 
Per cent. 
10.55 
22.00 
21.77 
28.79 
27.80 
Per cent, j Per cent. 
2.50 ! 2.79 
3.82 4.74 
5.01 ! 6.30 
8.65 ; 9.65 
5.56 7.48 
Per cent. 
2.60 
4.06 
5.08 
8.52 
5.44 
Per cent. 
2.72 
4.03 
4.87 
8.76 
5.31 
| 
5.11 6.19 '• 5.14 5.14 
Ratio wilting coefficient to capillary moisture. 
Fine material. 
Sample No. and description. 
Yellow 
pine. 
Lodge- 
pole. 
Douglas 
fir. 
Spruce. 
All. 
Silt. 
Clay. 
590. Sifted granite gravel with 
loam 
0.094 
.120 
.142 
.229 
.129 
0.105 
.149 
.178 
.256 
.174 
0.098 
.128 
.144 
.226 
.126 
0.102 
.127 
.138 
.232 
.123 
0.100 
.131 
.150 
.236 
.138 
Per cent. 
13.5 
45.8 
41.8 
53.3 
51.9 
Per cent. 
5.4 
604. Composite limestone 
602. Composite sandstone 
601. Prairie soil from shale 
11.4 
11.0 
17.2 
11.1 
Averages 
.1428 
.0346 
24.2 
.1724 
.0364 
21.1 
.1444 
.0324 
22.4 
.1444 
. 0348 
24.1 
.151 
.0389 
25.8 
Mean variations of single 
determinations 
Percent age o f mean varia- 
tions 

Sample No. and description. 
Ratio of wilting coefficient to moisture 
equivalent. 
Yellow 
pine. 
Lodge- 
pole. 
D °fir glaS S P ruce « 
590. Sifted granite gravel with loam 
0.237 
.174 
.230 
.301 
.200 
0.265 
.215 
.290 
.335 
.269 
0. 247 0. 258 
604. Composite limestone 
.185 : .183 
602. Composite sandstone 
. 233 . 224 
601. Prairie soil from shale 
. 296 I . 305 
603. Composite lava 
.196 .191 
Averages 
.2304 
.0328 
14.2 
.2748 
.0302 
11.0 
.2314 ! .2322 
Mean variation of single determinations 
.0328 1 .0394 
Percentage of mean variations 
14.2 17.0 
The wilting coefficient tests given in Table 3 bring out the follow- 
ing facts: 
1. The line showing the percentage of the mean variations indicates 
that the four species taken together and comprising 20 cases have a 
larger variation from an established mean ratio than any of the 
individual species. Lodgepole pine "shows the highest relative wilt- 
ing coefficient, and, since the other three species gave almost identical 
results, it follows that a ratio established by the promiscuous use of 
species would be most largely in error when applied to calculations 
for lodgepole. 
2. The relatively high wilting coefficient for lodgepole pine has 
been thoroughly established by numbers of other tests, which, how- 
