The following is selected from the
numerous data on the subject. Two soils, almost identical in
character, contained respectively 17.57 per cent and 16.55 per cent
of water on an average to a depth of eight feet; that is, the total
amount of water held by the two soils was practically identical.
Owing to varying cultural treatment, the distribution of the water
in the soil was not uniform; one contained 23.22 per cent and the
other 16.64 per cent of water in the first twelve inches. During the
first seven days the soil that contained the highest percentage of
water in the first foot lost 13.30 pounds of water, while the other
lost only 8.48 pounds per square foot. This great difference was due
no doubt to the fact that direct evaporation takes place in
considerable quantity only in the upper twelve inches of soil, where
the sun's heat has a full chance to act.
Any practice which enables the rains to sink quickly to considerable
depths should be adopted by the dry-farmer. This is perhaps one of
the great reasons for advocating the expensive but usually effective
subsoil plowing on dry-farms.
Pages:
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141