6 
COI^ORADO ExPI-RIMENT STATION. 
of 1901 and 1902 be compared, a great difference is seen. Those for 
1901 would be dangerous to all potato roots in the entire upper foot 
of soil. 
Keen observers among the farmers at Greeley were of the 
opinion that the great injury to the potato crop in 1911 had come 
during the extreme heat of the month of June. On inquiry, Mr. 
Max Mendelssohn, agricultural and chemical expert of the Great 
Western Sugar Company, told us that when he first came to the 
arid country from Germany, he had realized that a high soil temper¬ 
ature was one of the things to be contended with in beet sugar pro¬ 
duction. The writer was so fortunate as to secure from Mr. Men¬ 
delssohn’s associate, Mr. Asa C. Maxson, soil temperatures at Long¬ 
mont, close to the Greeley district, for 1911 and for the previous 
year, 1910, a favorable year for potatoes. These temperatures are 
given below and taken in connection with the Nebraska figures, show 
conclusively that the whole of the upper foot of soil may be as much 
as ten degrees warmer one year than another for the whofe of the 
critical month of Tune, and that, as a matter of fact, such was the 
case in igii as compared to loio. They show, also, that the cooler 
years, with more rain and cloudiness and less continuous and intense 
sunshine, are freer from the extrenies of soil temperatures that do 
the injury. June is the month, in the Greeley district, when potato 
roots are growing rapidly in the upper foot o-f soil and when the 
leaves do not, as yet, afford much shade to the soil. 
SOIL TEMPERATURES AT LONGMONT, COLORADO, 1910, TAKEN BY 
ASA C. MAXSON. 
At Two 
Inches 
At Six 
Inches 
Dates 
8 A. M. 
5 P. M. 
8 A. M. 
5 P. M, 
Degrees E. 
Degrees F. 
Degrees F. 
Degrees 
June 
1. 
. 61 
81 
58 
75 
June 
0 
. 72 
82 
64 
69 
June 
O 
. 41 
50 
50 
63 
Juno 
4. 
. 49 
82 
57 
68 
June 
5. 
. 51 
71 
57 
66 
June 
0. 
. 59 
69 
51 
64 
June 
7. 
. 59 
90 
52 
73 
June 
8. 
. 72 
87 
61 
76 
June 
9. 
. 64 
86 
54 
77 
June 
10. 
. 63 
80 
55 
73 
.Tune 
11. 
. 58 
94 
55 
81 
.Tune 
12. 
. 60 
74 
59 
68 
.Tune 
13. 
. 64 
65 
57 
63 
.Tune 
14. 
. 59 
90 
54 
72 
.Tune 
1.5. 
82 
63 
74 
.Tune 
18. 
. 69 
69 
64 
68 
June 
17. 
. 68 
82 
58 
73 
.Tune 
18. 
. 71 
99 
64 
85 
.r line 
19. 
. 76 
106 
69 
85 
.) n n e 
20. 
. 70 
90 
66 
80 
