NATIONAL MUSE UM MtUlUUfifif 
SUMMER TEMPERATURES OF THE SOIL. 
II 
correct within one degree. Placed \ in. below the surface 
of dry coarse sand the reading was 134 deg. Fah., and 
A in. under dark sandy loam it was 148 deg. On February 
13th, when the air temperature at Guildford was 91 deg. 
Fah., and the solar reading 143 deg., an accurate thermo- 
meter registered 150 deg. Fah. half an inch below the 
surface of dry dark loam, and 120 deg. Fah. at a depth of 
5 in. In the same spot the same tnermometer covered 
with half an inch of powdered slaked lime recorded 120 deg., 
or the same as at a depth of 5 in. in dark soil. In another 
place under light grey soil the reading was 130 deg. half 
an inch below the surface, and 100 deg. 5 in. down. 
Unfortunately, the regular observations made by the 
Meteorological Department did not assist much in the present 
study. Soil temperatures are taken regularly at 8 or 9 in., 
3 ft-> 5 ft., ana 8 ft., below the surface, but no records 
are available for the surface soil to a depth affected by 
cultivation. At Perth the maximum at 8 in. was 86 deg, 
on February 27th, 1907, the shade temperature being 90.8 
deg. The monthly readings at 8 in. do not vary much. 
Although solar temperature records are not considered very 
reliable, they are a good guide for the present purpose. 
On November 19th, 1910, the solar reading at Charlotte 
Waters was 198 deg. Fah., while the shade temperature 
was 112.2 deg. Fall. In January, 1908, the solar readings 
at Eucla ranged from 167 to 179 deg. seven times. The 
mean yearly solar temperature at Coolgardie is 138.5 deg. 
Fah. The Commonwealth Meteorologist thinks that it is 
fair to assume that rock surface exposed to the sun may 
reach anything from ibo to 200 deg. Fah. 
Mr. Grasby suggested that it might be reasonably assumed 
that the combination of summer dry heat, followed by the 
vivifying rains while the soil was still warm, afforded the 
necessary conditions described by l)rs. Russell and 
Hutchison, and it was desirable to have observations made 
in the wheat areas. If possible the temperature of the soil 
should be read at 1 in. and 5 in. below' the surface. The 
colour and character of the soil should also be mentioned 
The character does not appear to matter much, but it 
would be best to state whether it was sand, loam, or clay. 
