The
incorporation of organic matter with the soil, which tends to darken
the soil, has a slight though important bearing on germination as
well as on the general fertility of the soil, and should be made an
important dry-farm practice. Meanwhile, the temperature of the soil
depends almost wholly upon the prevailing temperature conditions in
the district and is not to any material degree under the control of
the farmer.
A sufficient supply of oxygen in the soil is indispensable to
germination. Oxygen, as is well known, forms about one fifth of the
atmosphere and is the active principle in combustion and in tile
changes in the animal body occasioned by respiration. Oxygen should
be present in the soil air in approximately the proportion in which
it is found in the atmosphere. Germination is hindered by a larger
or smaller proportion than is found in the atmosphere. The soil must
be in such a condition that the air can easily enter or leave the
upper soil layer; that is, the soil must be somewhat loose. In order
that the seeds may have access to the necessary oxygen, then, sowing
should not be done in wet or packed soils, nor should the sowing
implements be such as to press the soil too closely around the
seeds.
Pages:
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205