This shows itself in a decreased percentage of
germination. The effect upon germination of the percentage of water
in the soil is well shown by some of the Utah experiments, as
follows:--
Effect of Varying Amounts of Water on Percentage of Germination
Percent water in soil 7.5 10 12.5 15 17.5 20 22.5 25
Wheat in sandy loam 0.0 98 94 86 82 82 82 6
Wheat in clay 30 48 84 94 84 82 86 58
Beans in sandy loam 0 0 20 46 66 18 8 9
Beans in clay 0 0 6 20 22 32 30 36
Lucern in Sandy loam 0 18 68 54 54 8 8 9
Lucern in clay 8 8 54 48 50 32 15 14
In a sandy soil a small percentage of water will cause better
germination than in a clay soil. While different seeds vary in their
power to abstract water from soils, yet it seems that for the
majority of plants, the best percentage of soil-water for
germination purposes is that which is in the neighborhood of the
maximum field capacity of soils for water, as explained in Chapter
VII. Bogdanoff has estimated that the best amount of water in the
soil for germination purposes is about twice the maximum percentage
of hygroscopic water.
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