AIR, AND THE GROWTH OF CROPS. The importance of air as an agent in the growth of crops is but little known by the majority of farmers. The action of the oxygen of the air in connection with heat and moisture causes the seed to germinate, and during the whole growth of the plant, air is essential to growth and the proper ripening of the seed. For this reason the ground is required to be kept mellow; for tbis reason we cultivate often and thoroughly, and to enable the soil to become aerated, we break the crust as often as it is formed. As showing the importance of air in the soil, a series of experi ments made some years ago exhibits the agency of air and carbonic acid gas in the growth of crops. These experiments were made with three glfiss vessels, in depth two and a half feet, which were filled with soil of a like character, and planted in oats and peas. They grew 110 days, and then the plants, with their roots, were taken out and driK1 and their ashes analyzed, and the soluble mineral substances ascertained that were left in the soil. In one of these ves.iels no air was introduced; in another, it was by a hole in the bottom of the vessel; and in the third one, air and carbonic gas by the same means, The result is as follows, the estimates being made for the acre: Experiment without additional sup ply of air—quantity of dry plants, in pounds, per acre—oat plants, 1,560; pea plants, 688; roots of both, 108. Soluble mineral substances, in pounds, per aere—in the ashes of the plants, 208 left in the soil, 608. Experiment with supply of air— quantity of dry plants, in pounds, per acre—oat plants, 3,060; pea plants, 984: roots of both,152. Soluble inineral substances, in pounds, per aere— in the ashes of the plants, 380; left in the soil, 1,104. Experiment with supply of air and car
bonic gas--quantity of dry plants, in pounds, per aere—oat plants, 3,396; pea plants, 1,304; roots of both, 240. Soluble mineral substances. in pounds, per acre—in ashes of plants, 448; left in the soil, 1,54-8. These experitnents exhibit the important action of air and carbonic gas in the growth of vegetable matter The first increased the plants in size about eighty per cent. ; the min eral substances in the plants about eighty per cent., and the soluble minerals left in the soil about eighty per cent. The' carbonic gas in creased the growth of plants over that eaused by air alone about thirty per cent. ; the mineral sub stances absorbed by the plant thirty-five per cent., and the soluble minerals left in the soil about sev enty-five per cent. The element of the air which causes such important action is its oxygen. It is the great destroyer either by rapid burning or by slow decay. It is this which, uniting with the wood of plants, turns it into carbonic gas. It aids in rendering soluble the insoluble rninerals of the soil; that is, it so changes them that they dis solve in water and are carried by it into the roots of the plants. Hence it is tbe great destroyer of the mould of the soil, as before stated, turning it into carbonic gas, and thus making it useful to form new vegetable growths. By returning these to the soil we increase the amount of the mould, for in addition to the amount of carbonic gas they haye derived from the old mould, they have received much from -the atmosphere.