SPRING CEREALS AT MORO, GREG. 5 
Table I. — Composition of silt loam soil in the Columbia Basin. 
Constituents. 
Total. 
Soluble 
in 
1.115HC1. 
Constituents. 
Total. 
Soluble 
1.115 HC1. 
Silica (Si0 2 ) 
Per cent. 
62.85 
1.63 
4.52 
1.94 
.04 
Per cent. 
0.34 
.74 
3.05 
1.66 
Iron and aluminum oxids 
(Fe 2 3 and A1 2 3 ) 
Per cent. 
8.47 
.30 
.11 
.37 
Per cent. 
Potash (K 2 0) 
8.37 
Lime (CaO). 
Phosphoric acid (P 2 5 ) 
.21 
Manganese oxid (Mn30 4 ) 
Volatile .. 
From analyses of surface soil obtained from both virgin and cropped 
areas Bradley concludes that " while the percentage of nitrogen in 
these soils has remained practically constant under continual crop- 
ping for, in extreme cases, 25 years, there has been a marked decrease 
in the carbon or organic content." Probably on account of this 
deficiency in humus the surface soil at the substation is inclined to 
run together or pack in the spring from the effects of winter precipi- 
tation. 
The soil is remarkably uniform in texture, absorbs water readily, 
and has a high moisture-holding capacity. At the substation the depth 
of the soil to the rock formation underneath varies from 1 to 9 feet, 
the deeper soil being on the higher elevations and on the northward 
slopes. Where the ground slopes toward the west or southwest, the 
soil usually is shallow and therefore less suited to cereal production, 
because of its inability to store sufficient moisture to mature crops. 
Most of the farm had been cropped to grain for about 25 years prior 
to the establishment of the substation. 
CLIMATIC CONDITIONS. 
Careful records of climatological phenomena have been kept since 
January, 1910, in cooperation with the Biophysical Laboratory of 
the Bureau of Plant Industry. The weather-observing equipment 
consists of standard snow and rain gauges, maximum and minimum 
thermometers, self-recording thermographs, an evaporation tank, 
an anemometer, and a psychrometer. 
PRECIPITATION. 
In no other place in the world is cereal production conducted on 
such an extensive scale with so little precipitation as in the Colum- 
bia Basin. As Table II shows, the lowest annual precipitation 
in the vicinity of Moro during the past 10 years has been 7.68 inches. 
The precipitation for the years from 1905 to 1909, inclusive, was 
recorded at Grass Valley, which is about 10 miles south of Moro, 
while that for the years 1910 to 1915, inclusive, was recorded at the 
substation. The average annual precipitation for the 11-year period 
from 1905 to 1915 is 11.35 inches. The highest annual precipitation 
since records have been kept at the substation is 14.89 inches. 
