PLOUGHING.

Globe, Volume XXII, Issue 1905, 2 April 1880, Page 2

PLOUGHING.

[From the “Prairie Farmer.”] The great purpose of ploughing is to pulverise the soil, and thus enable the rootlets to search for food and the air and water to find its way through its pores. It gives the power of destroying the life of weeds, mingling them with the soil and hastening their decay. Late autumnal ploughing does much towards killing insects and eggs or larva. The latter often penetrates some inches below the surface. Ploughing exposes them to the frosts. But the great object most farmers have in view is to mellow the soil, increase its porosity and augment the amount of air that may disintegrate and decompose the vegetable, animal and mineral ingredients and fit them for nourishing coming plants. Wo all know how valuable is air to maintain vegetable and animal life. Its oxygen enables animals to breathe and live and its carbonic acid feeds and gives firmness to living plants. The presence in the air, or soil of oxygen promotes the starting into growth of seeds. Many germs may remain dormant for many years, while excluded from the air, but start at once when exposed to air, warmth and moisture. The air also begins the decay of the vegetable matter in the soil and resolves it into simpler forms of matter, and evolves carbonic acid and water that contributes largely to the growth of vegetable infancy. If a small amount only of air be present, decomposition may slowly occur but may generate new compounds, that may injure or retard the growth of plants. Exclude the usual percentage of oxygen, and the vegetable matter of the soil abstracts oxygen from such earthy matters as may decompose and lose their usual state of oxidation. It takes oxygen from sulphates and changes them to sulphides. These lower oxides are harmful to vegetation. We prevent these injurious changes by ploughing, harrowing, and loosening the soil so as to admit air freely to every particle of soil. Give the soil all the air it can absord and it will fit it for the nourishment of plants. A poor supply of air harms plants as much as animals.

Compound mineral substances in soils require a constant supply of oxygen to hasten or promote their decomposition and so enrich the soil. These decomposing minerals yield largo supplies of inorganic materials that feed and foster growing crops. Air, then, aids the decay of this mineral matter and helps to bring carbonic acid in contact with plants. In this way we clearly see that a porous soil and exposure to air favors the growth of plants by presenting to their roots a full supply of organic and inorganic food. Ammonia and nitric acid are generated in soils. They are of great value |to vegetable life. They are the more abundant, the more often the land is ploughed and harrowed. All elements that the surface soil absorbs from the air will be the greater the more and oftener the entire soil is exposed to oxygen. The better the farmer ploughs, harrows, and pulverizes his land, the larger are his crops. If soils are pervious to the air, the rootlets can easily penetrate the soil. Their fibres spread far around, and are fully supplied with food. A well pulverized and mellow soil, that can be freely entered by air and roots, will yield larger crops thnn when a greater depth, but less permeable soil exists. A deep soil is always able to yield larger crops than a shallow one, other conditions being the same.