New England Farmer 2(7):115-116 (March 30, 1850)
NAKED FALLOWS AND NAKED SOILS TEND TO STERILITY.
There is no doubt of the truth of this proposition. Any observing man who has travelled far, and observed carefully what was before him, cannot have failed to note this result. Occasionally old fields, or commons at the north, and whole plantations at the south, illustrate the assertion; while in ancient kingdoms, once world-wide renowned for fertility, as Palestine, large portions of Syria, Greece, Italy, and Spain, sterility now reigns supreme, where once the golden harvests waved in the richest profusion, and lowing herds and bleating flocks fattened on the luxuriant meadows and grassy hill-sides. A few years of bad cultivation, followed by abandonment of the naked surface to the elements, have wasted the remnant of fertility left by the last thriftless occupant. A little consideration will show the inevitable tendency of such management to similar results in our own country.
A soil judiciously cultivated, where all that is produced upon it is fed off upon the field; or the refuse vegetation, as of stalks and roots, after its consumption by man or animals; the offal of the finer portions, as of grain, the leguminous plants or farinaceous roots,—where those are carefully husbanded and returned to the soil, with the addition comparatively of a trifle in some of the essential mineral ingredients, as of plaster, lime, or salt, when they are deficient, the soil will be constantly improving. The reason of this is perfectly obvious. Vegetation draws no inconsiderable share of its carbon, which is between forty and fifty per cent. of its entire weight, from the carbonic acid of the atmosphere. This is stored up in the roots, stalks, and leaves; and if carried back to the soil and incorporated with it, tends greatly to augment its fertility. In fruits fed to man or animals, much of this carbon is converted into carbonic acid, and given again to the atmosphere by their respiration. Yet much of the carbon, and nearly all the salts, or mineral ingredients of the food, are retained in their faeces; and if these are applied to the field, they will be found to have improved, rather than deteriorated, the soil from which they had been taken.
It is the loss by the partial fermentation and decomposition of plants, grains, and grasses, in the curing and preparation for food, in addition to their large waste from respiration in the animal system, which renders the promlem of improvement by manuring with green crops (in which the whole product, as of oats, buckwheat, rye, clover, or cow peas, grown upon a field, is turned under by the plough) so much more speedy and efficient, than the slower, yet not less certain mode of restoring all the offal and manure derived from the crop to the soil where it has been grown. Even a small quantity of such mineral manures, as lime, plaster, salt, or bone-dusts has a tendency to absorb carbonic acid and ammonia; and by a small outlay, the fertility of the soil may be greatly increased, and the loss of these fertilizers by respiration and perspiration, when they first pass through the animal system, before their residuum is given back to the soil, may be fully compensated.
One exception is to be admitted of the tendency of uncultivated fields to sterility. This is seen where they sustain a natural growth of vegetation, such as is exhibited in woodlands, prairies, and the spontaneous growth of other plants in tolerable profusion; for here the work of a sell-sustaining fertility is constantly in operation. In all other cases, the rule holds true, and from this perfectly plain and obvious principle. If the soil be upturned and exposed to the sun, air, and rains, unsheltered by the kindly protection of its natural covering of vegetation, the oxygen from the air, and moisture it imbibes, stimulated by the sun's rays, acts upon the carbon of the soil, and converts it into carbonic acid; and this, finding no rootlets of plants to absorb and condense it, speedily escapes to the surface, where it mingles with the atmosphere, and is wafted thousands of miles from the spot of its origin. As they become soluble, the earthy salts, finding no plants to appropriate them, are soon washed out of their native bed by the drenching rains, and pass onward through rills, brooks, and rivers, to the mighty ocean, hopelessly beyond reach. Calcareous and aluminous soils are partial, and only partial, exceptions to this general result. They absorb a certain amount of these fertilizing salts and gases, while all beyond pass off into irreclaimable waste.
The relevancy of these principles is shown, by the devastations of numerous and once fertile cotton plantations in our Southern States. It was not the quantity of carbon and salts, (ash,) abstracted in the comparatively small proportion of lint, (pure cotton,) taken from the fields, although this, in a long series of years, would be considerable; but it is owing to the necessarily cleanly cultivation required by this crop, and the nearly naked fallows thereby exposed to the drenching rains and an almost tropical sun. No weeds nor grass must be suffered to grow where a good crop is to be secured; and the narrow strips, (rows,) of vegetable growth, which alone are suffered to usurp the field, except for the brief time when the crop is in full foliage, gives every facility for the escape of fertilizing matter through the action of the elements. Added to this, is the too frequent waste of the stalks, leaves, and seeds; the two former being often suffered to decay on the surface and gradually disappear from rains; and the latter succeeds, at a later period, the other portion. of the plant; or if fed to cattle or swine, their manure is dropped in the roads or by the sides of gullies, where it soon follows the same channels.
A similar effect is produced from the constant cultivation of grain, tobacco, flax, and most other plants; and from their abstracting a greater amount of the fertilizing elements to give them maturity, than are taken out of the soil by cotton, this result is sooner reached.
What is the remedy for this? is the very pertinent inquiry. There are but three, and one or more of these must be applied, or sterility is inevitable. The fields must have a frequent rotation of grass, clover, or some of the forage plants fed off, where grown, by animals, and their droppings left to fertilize the surface; they must be restored by green crops ploughed in, as of clover, cow pea, or other crops, or they must be manured from the cattle yard, or its equivalent in mineral and vegetable manures. Each of these mode. has been often treated of in our preceding volumes, and they will continue to be noticed in all their varying phases and merits in the succeeding ones.—Am. Agriculturist.