212 
Journal of Agricultural Research 
Vol. XI. No. 5 
Agaricus tabularis fruited only once in 1909, the fruiting period ex¬ 
tending over 17 days. At this period the soil-moisture determina¬ 
tions in short-grass land showed available moisture in both the first and 
second foot, and the mean soil temperature of 65° 1?. The mean air 
temperature was a little lower, 62°, and the range in air temperature 
from 41 to 91 °. The daily evaporation rate was relatively high, amount¬ 
ing to 0.218 inch from the free-water surface of a 6-foot tank. The 
rainfall averaged 0.29 inch per day, or a little greater than the evapora¬ 
tion. 
In 1915 Agaricus tabularis fruited twice, the June period covering 20 
days and the August period only five days. Soil-moisture conditions 
were favorable during both of these periods. Conditions of evaporation 
were similar. Although but a small amount of rain fell during the late 
period, the percentage of days with rain was very high. Soil tempera¬ 
ture was high during the late period. During the early period continu¬ 
ous soil temperature records were not available, but occasional records 
showed the temperature to have differed but little from the temperature 
of the early period in 1909. The air temperatures did not differ markedly 
from those of 1909, except that the maximums were much lower for each 
crop. A comparison of the conditions in 1909 with those of 1915 shows 
only a slightly higher evaporation and higher maximum temperature 
in 1909. The effect of the more extreme conditions on the fruiting 
bodies of the fungi will be noted later. 
Calvatia cyathiformis , which fruits later in the season, usually fruits 
during periods of higher evaporation and higher temperatures. In 1909 
the first fruiting period extended over eight days. The mean soil tem¬ 
perature was a little higher then than during the Agaricus period and 
the evaporation a little more extreme, but the air temperature range 
not as great. Otherwise, conditions were similar. The second fruiting 
period came during July and lasted only five days. The soil tempera¬ 
ture was unusually low, the air temperature reached its maximum on 
the last day of the period. Evaporation was high and there was no 
rain. The soil was rapidly drying off. This second fruiting period 
followed a rainfall of 2.39 inches on July 7. The soil of the first foot 
was moist, but that of the second foot dry during this period. 
In 1915 the June fruiting period covered 11 days. The soil was moist at 
this time and the air temperature rather high, but the evaporation was 
unusually low. During this damp period with frequent rain and low 
evaporation the fruiting bodies were produced under conditions markedly 
different from those of 1909, in so far as aerial conditions are concerned. 
The second fruiting period covered only four days in August. The 
mean temperature of the soil was 71 0 F., although the air temperature 
was rather low. This period followed a period of rainy weather, as is 
shown by the 10-day period preceding. The evaporation was unusually 
low, and rain was recorded on four of the five days considered. 
