The drains also, from causes already named (3), keep the soil warmer than before being drained, thus actually lengthening the season, by making the soil warm enough for vegetable growth earlier in spring, and later in autumn.
How does it prevent lands from becoming sour?
Why does it hasten the decay of roots, and the comminution of mineral matters?
How does it prevent the abstraction of heat from the soil?
15. Lands are prevented from becoming sour by the formation of acetic acid, etc., because these acids are produced in the soil only when the decomposition of organic matter is arrested by the antiseptic (preserving) powers of water. If the water is removed, the decomposition of the organic matter assumes a healthy form, while the acids already produced are neutralized by atmospheric influences, and the soil is restored from sorrel to a condition in which it is fitted for the growth of more valuable plants.
16. The decay of roots, etc., is allowed to proceed, because the preservative influence of too much water is removed. Wood, leaves, or other vegetable matter kept continually under water, will last for ages; while, if exposed to the action of the weather, as in under-drained soils, they soon decay.
The presence of too much water, by excluding the oxygen of the air, prevents the comminution of matters necessary to fertility.
How much heat does water take up in becoming vapor?
Why does water sprinkled on a floor render it cooler?
Why is not a cubic inch of vapor warmer than a cubic inch of water?