CEREAL EXPERIMENTS AT THE AKRON FIELD STATION. 7 
month from April to September, inclusive, in the 8-year period, 1908 
to 1915, is given in Table IV. . The precipitation for the same period 
is included, and the ratio of precipitation to evaporation each year is 
also given. The data show that evaporation from the free water 
surface increases when precipitation decreases, but not in exact ratio. 
The highest evaporation was recorded in 1911, but the lowest pre- 
_ cipitation occurred in 1913. The year of loraeet evaporation was 
1915, which was also the year of highest precipitation. The ratio 
of precipitation to evaporation over the total period for which records 
are available is 1 to 2.9. 
TasiEe 1V.— Monthly precipitation and evaporation from a free water surface at the Akron 
Field Station, Akron, Colo., from April to September of each year, 1908 to 1915, 
ancluswe, 
[Data (in inches) from the records of the Biophysical Laboratory of the Bureau of Plant Indusiry.] 
April. May. June. July. August. |September. Total. 
a Eapemecgeee) er igec is |e is.) 2 | si] 2) 8) s 
ear. a — 4 — 1 = 
easels bee ele |e) 8) eB | els 
© eS 7) S D eS o S D S 2) S 2 S = 
an a Fa Ea rt a a a af ea a > A a 3 
my oa Ay co Ay x Ay 3 Ay | om oo) Ay 3) ae 
iM aaeseoae 1.70} 4.740) 3.57] 7.709] 2.35) 8.637] 3.40} 8.474) 1.62] 7.826] 0.22) 8.550) 12.86] 45.936] 1:3.5 
CU Sea Raeee .40| 4.734] 1.87] 6.825} 3.32) 7.003) 4.61] 9.396] 3.77) 8.538) 2.16) 5.857] 16.13] 42.353] 1:2.6 
TOOK oS Ses. 3.96} 6.387] 2.06] 5.797] 1.38) 8.722) 1.47] 9.763] 3.72) 7.142) 3.81] 5.810] 16.40} 43.621] 1:2.6 
iQ SaaS Sees 2.63) 5.841) 1.15] 7.323) 1.48) 9.753) 1.34] 9.774) 1.30) 8.944] 2.40) 7.183] 10.30} 48.818] 1:4.8 
HOD Ee laa ns = 2.49} 4.576) 2.86] 7.097] 3.39] 6.750) 3.58} 7.618} 1.58] 7.048] 1.88] 4.648] 15.78] 37.737] 1:2.3 
NOES iol icine 2.19) 4.336] 1.44] 5.835] 1.35) 8.178] 1.85) 9.259] 1.14] 9.302] 2.08} 6.040} 10.05] 42.950) 1:4.2 
HOU 4.01] 4.290) 1.46] 5.608) 3.54] 7.509] 1.66} 8.654] 1.05) 8.364) .23] 7.438] 11.95] 41.863] 1:3.5 
HOU Dial spel=j== - 5.19} 4.220) 4.13) 5.033} 3.75} 5.883) 1.10] 6.660] 3.5 | 5.820) 1.76) 5.793] 19.44] 33.409] 1:1.7 
Average. .| 2.82| 4.890 2.32 6.403] 2.57} 7.804] 2.37] 8.699] 2.21) 7.873] 1.82] 6.415) 14.11] 42.084] 1:2.9 
The precipitation and evaporation in the months of August and 
September are less important in the production of spring-sown 
cereals than in the production of those sown in the fail. The ger- 
mination of winter wheat is often slow and sometimes very poor, 
due to the scarcity of moisture in the seed bed at the time of sowing. 
Crop growth and surface evaporation may have exhausted the 
moisture from the surface below the seeding depth, even though 
the lower levels contain sufficient moisture to maintain plant 
Srowth. _ 
Very low humidity of the atmosphere, rapid transpiration from 
srowing plants, and high wind velocity are responsible for the rapid 
and often premature ripening of cereals. For this reason the early- 
maturing varieties in each group usually produce a higher quality of 
grain than the later ones. The growth of all is checked at about the 
same time. 
