This would not be far from the field-water
capacity as described in the preceding chapter.
During the absorption of water, seeds swell considerably, in many
cases from two to three times their normal size. This has the very
desirable effect of crowding the seed walls against the soil
particles and thus, by establishing more points of contact, enabling
the seed to absorb moisture with greater facility. As seeds begin to
absorb water, heat is also produced. In many cases the temperature
surrounding the seeds is increased one degree on the Centigrade
scale by the mere process of water absorption. This favors rapid
germination. Moreover, the fertility of the soil has a direct
influence upon germination. In fertile soils the germination is more
rapid and more complete than in infertile soils. Especially active
in favoring direct germination are the nitrates. When it is recalled
that the constant cultivation and well-kept summer fallow of
dry-farming develop large quantities of nitrates in the soil, it
will be understood that the methods of dry-farming as already
outlined accelerate germination very greatly.
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