This section is from the book "The Gardener's Monthly And Horticulturist V18", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
I wish also to dissent from the opinion of the editor, and say that they do. Air plants are no more fair examples than fresh water Alga? would be; but let us take common agricultural and garden plants.
If moist air, or the vapor in it, is enough for plants, how can they obtain any of the ash constituents, nitrogen or hydrogen? Perhaps a little of the two latter from the air, but none of the ash. These must be in solution in water in its liquid state.
But it is a question if vapor of water is taken up at all by the roots. Sachs and Knop, in their experiments, found roots would not absorb, but rather exhale, vapor. Free water injures the roots of most plants if they are long confined in it, it is true, but when drained off there is left capillary and hygroscopic water, and with this the plant grows in the most healthy manner. This is the principle of underdraining land, and there is, of course, moist air in the soil, because it is then open, with air circulating in it; and this air, if there is sufficient water in the soil, will be moist air - so that it is true that plants need moist air, but this only as a necessity from having a well-drained soil with water in it, not bottom water, but capillary and hygroscopic.
So keep the hole open in the bottom of the pot and let the plants have a chance to have moist air, but do not keep the soil as an old lady of my acquaintance advised - "a muddy wet,"
While the editor says we want moist air in the soil, not water, I say we want moist air in the soil and water, and the water furnishes nearly all the food of the plant, save carbonic acid.
For the highest authority in the world on this subject, I refer the reader to " How Crops Feed," by Prof. S. W. Johnson, pp. 36 and 200.
[We do not know that we have any objection to make against this statement, We are reminded of the good minister who objected to dancing, but who was opposed by a gay young parishioner who thought she had Scripture to justify her, and she quoted that " David danced before the ark." "Ah!" quoth he, "David danced singly and alone. If you want to dance as David did, go on." Now, there is water in every thing. In every one hundred pounds of wheat flour there is sixteen pounds of water, but it appears quite dry to us, and we suppose there is no earth that the gardener ever handles so dry but contains "water." But the water we refer to is of another kind. Wet and dry, horticulturally, are technical terms. To the gardener, when the earth "smears " - makes a paste when he presses it - it is wet, contains water; when it rather powders under pressure, it is dry to him. There is water there, of course, in a chemical sense, but not in the horticultural one. - Ed. G. M.]