208 
Journal of Agricultural Research 
Vol. vn. No. 4 
of transpiration with evaporation as shown by the square of the mean 
correlation coefficients is as follows: Evaporation (shallow tank), 55 per 
cent; wet-bulb depression, 50 per cent; evaporation (deep tank), 35 per 
cent; temperature, 32 per cent; radiation, 27 per cent; and wind, 6 per 
cent. 
Table XXIII .—Correlation of transpiration of legumes with intensity of weather factors 
and with evaporation 
Tempera¬ 
ture. 
Wet-bulb 
depression. 
Evaporation. 
Plant. 
Year. 
Radiation. 
Shallow 
tank. 
Deep 
tank. 
Wind. 
Cowpea. 
1914 
0. s6±o. 06 
0. 72 ±0.04 
o* 82 ±0.03 
0.79 ±0.03 
0.73 ±0.04 
0.31 ±0.08 
Do. 
1915 
1914 
. 7 S± .OS 
• 38± • 09 
. 6g± . 06 
.82± .04 
. 57± • 07 
.04± .11 
Lupine. 
• S8± .06 
.63± .06 
* 75 ± -°4 
.76± . 04 
.68± .05 
• 36± .08 
Alfalfa, E23-20-52. 
1914 
• 40± .06 
• 48± • 06 
• 67 ± .04 
.67± .04 
•54± .05 
.a8± .07 
Alfalfa, 162-98A.. 
1914 
• 42 ± .06 
• 4 S± .06 
.67± .04 
. 69± . 04 
• 55 ± -05 
• 2 S± .07 
Do. 
Alfalfa, E23 (in inclos- 
1915 
• S2± .07 
■ 74 ± • °4 
• 6s± .05 
.78± . 04 
.6i± .06 
• I 9 ± -09 
lire). 
1914 
• 43 i *06 
• 50± .06 
. 70 ± . 04 
• 74 ± -03 
.$6± .05 
• 32± .07 
Do. 
1915 
1914 
• 52± .06 
. 47 ± .06 
. 7i± .04 
. 66± .05 
.69± .06 
. 50± .06 
. i8± . 08 
Alfalfa, E23 (in open)... 
• 55 ± * °5 
• 76 =fc .03 
. 7 fl± .04 
• 58 ± *05 
• 3 i± -07 
Mean of 1914 coeffi- 
.48 
*56 
• 73 
• 73 
. 61 
•31 
Mean of all coeffi- 
cients. 
Square of mean of 
■52 
•57 
.71 
•74 
•59 
•25 
1914 coefficients... 
Square of mean of 
*23 
• 3 i 
•53 
• 53 
•37 
. 10 
all coefficients.... 
.27 
•32 
•50 
•55 
•35 
. 06 
CORRELATION OF DAILY TRANSPIRATION OF ALL CROPS, CONSIDERED AS A 
SINGLE POPULATION, WITH THE INTENSITY OF WEATHER FACTORS 
The degree of correlation of the various weather factors with the 
transpiration ratios of all the plants considered as one population has 
also been determined. The coefficients for the two years are given in 
Table XXIV, together with their squares. They show the same rela¬ 
tionships as in the crop groups. The mean values of the squares of the 
correlation coefficients for the two years are as follows: Wet-bulb depres¬ 
sion, 0.55; temperature, 0.38; radiation, 0.30; wind, 0.04; evaporation 
(shallow tank), 0.56; and evaporation (deep tank), 0.33. 
Table XXIV .—Correlation of transpiration of all crops , considered as a single popii - 
lation, with weather factors, based on logarithmic differences of consecutive days 
Weather factor. 
1914 
1915 
Correlation 
coefficient. , 
Square of 
correlation 
coefficient. 
Correlation 
coefficient. 
Square of 
correlation 
coefficient. 
1. Radiation. 
0. 50 ±0. 01 
0. 25 
0. 59±o. 02 
0-35 
2. Temperature. 
. 64± . OI 
.41 
. 59 ± • 01 
•35 
3. Wet-bulb depression. 
. 79± . 01 
.62 
.691b .01 
.48 
4. Evaporation (shallow tank).. 
. 72± . 01 
• 52 
■ 75 ± - OI 
• 59 
5. Evaporation (deep tank). 
. 63 zb • OI 
.40 
. 5i± .02 
. 26 
6. Wind velocity. 
, 26± . 02 
.07 
. I4± • 02 
. 02 
