92 BULLETIN 1059, U. S. DEPARTMENT OF AGBICUI/TUBE. 



Table 3. — Wilting coefficients of four species in five types of soil. 



Sample No. and description. 



590. Sifted granite gravel with loam . 



604. Composite limestone 



602. Composite sandstone 



601. Prairie soil from shale 



603. Composite lava 



Moisture 

 Capillary equiva- 

 moisture. lent 

 100-G. 



Averages. 



Per cent. 

 26.58 

 31.85 

 35.31 

 37.77 

 43.16 



Per cent. 

 10.55 

 22.00 

 21.77 

 28.79 

 27.80 



Mean wilting coefficient. 



Yellow 

 pine. 



Lodge- Douglas 

 pole. fir. 



Per cent. 

 2.50 

 3.82 

 5.01 

 8.65 

 5.56 



l'tr cent. 

 _'. 79 

 4.74 

 6.30 

 9.65 

 7. 18 



Per c> nt. 

 2.60 

 4.06 

 5.08 



5. 1 I 



Engel- 

 mann 

 spruce. 



5.11 



6.19 



5. 1 1 



Per cent. 

 2.72 

 1.03 

 L87 



8. 7»V 



5. 1 1 



Sample No. and description. 



590. Sifted granite gravel with 



loam 



604. Composite limestone 



602. Composite sandstone 



601. Prairie soil from shale 



603. Composite lava 



Yellow 

 pine. 



Lodge- 

 pole. 



fir. 



Ratio wilting coefficient to capillary moisture. Fine material. 



I i 



Doughs Bpruce A]1 snt ( . lay 



Percent. Percent. 



0.1 1 hi L3.5 5.4 



.131 16.8 11.4 



.150 41.8 11. 



.236 53.3 17.2 



.138 51.9 11.1 



0.094 

 .120 

 .142 

 .229 

 .129 



0. 105 

 .149 

 . 178 



.174 



0.098 

 .128 

 .144 

 .221 

 .128 



ii. in.' 

 .127 

 .138 

 . 232 



. 1 23 



Averages 1428 .1721 



Mean variations of single 

 determinations 034ii . 0364 



Percentage of mean varia- 

 tions 24.2 21.1 



. mi 

 . 0324 

 22. 1 



Sample No. and description. 



590. Sifted granite gravel with loam 



604. Composite limestone 



602. Composite sandstone 



601. Prairie soil from shale 



603. Composite lava 



Averages 



Mean variation of single determinations 

 Percentage of mean variations 



Ratio of wilting coefficient to moisture 

 equivalent. 



Yi-llow 

 pine. 



0.237 



. 171 



2 

 .301 

 .200 



I.n L'r- 



pole. lir. 



.215 



0.247 

 .185 



.196 



Spruce. 



. l S3 



.305 

 .191 



11. -J 



.2748 



.0302 



ll.ii 



11. J 



. 2322 



17.ii 



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 almosl 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- 



