Drypoint

“ A peculiarity in the climate of the plateau which deserves to be noticed is the extreme dryness of the atmosphere. In summer the rains which fall are slight, and they are soon absorbed by the thirsty soil. There is a little dew at nights, especially in the vicinity of the few streams; but it disappears with the first hour of sunshine, and the air is left without a particle of moisture. In winter the dryness is equally great; frost taking the place of heat, with the same effect upon the atmosphere. Unhealthy exhalations are thus avoided, and the salubrity of the climate is increased ”

“ In the summer season, most commonly of any, the air becomes hot and dry. The surface of the Earth loses the moisture of the air’s influence, together with the Sun’s heat evaporating the dampness, becomes generally arid, and fails thereby to be a conductor of the moisture from below.
As a season of very dry atmosphere occurs for months at times, the soil becomes correspondingly dry and dusty to quite a depth. From this cause the springs and water in wells recede and sink away. ”

“ These springs are not what are known as surface springs—that is, the residue of a former exceptionally wet season, issuing from the foot of some well-soaked hill or ridge—but strong volumes of water that vary not in any season, totally unaffected by drought; in fact, running stronger during dry weather. ”

“ Naturally, the amount of the natural precipitation accounted for in the upper eight feet will depend upon the dryness of the soil at the time the investigation commenced. If at the beginning of the wet season the upper eight feet of soil are fairly well stored with moisture, the precipitation will move down to even greater depths, beyond the reach of the soil auger. If, on the other hand, the soil is comparatively dry at the beginning of the season, the natural precipitation will distribute itself through the upper few feet, and thus be readily measured by the soil auger. ”

“ It would be difficult to imagine a more diversified topography than is possessed by the dry-farm territory of the United States.
Uniform climatic conditions are not to be expected over such a broken country. The chief determining factors of climate—latitude, relative distribution of land and water, elevation, prevailing winds—swing between such large extremes that of necessity the climatic conditions of different sections are widely divergent. Dry-farming is so intimately related to climate that the typical climatic variations must be pointed out. ”

“ The dry soil layer then prevents further loss of water, and the wind because of its intensity has helped to conserve the soil-moisture. Similarly in localities where the relative humidity is low, the sunshine abundant, and the temperature high, evaporation may go on so rapidly that the lower soil layers cannot supply the demands made, and the topsoil then dries out so completely as to form a protective covering against further evaporation. ”

“ It is always dangerous to permit the soil of a dry-farm to become very dry, especially below the first foot. Dry-farms should be so manipulated that even at the harvesting season a comparatively large quantity of water remains in the soil to a depth of 8 feet or more. The larger the quantity of water in the soil in the fall, the more readily and quickly will the water that falls on the land during the resting period of fall, winter, and early spring sink into the soil and move away from the topsoil. ”

“ Meanwhile, the water-dissipating forces of the dry-farm section are not wholly objectionable, for whether the land be cultivated or not, they tend to hasten the formation of dry surface layers of soil which guard against excessive evaporation. It is in moist cloudy weather, when the drying process is slow, that evaporation causes the greatest losses of soil-moisture. ”

“ In the consideration of the downward movement of soil-water it is to be noted that it is only when the soil is tolerably moist that the natural precipitation moves rapidly and freely to the deeper soil layers. When the soil is dry, the downward movement of the water is much slower and the bulk of the water is then stored near the surface where the loss of moisture goes on most rapidly. ”

“ Between twelve and one o'clock, the rain which had been pouring down steadily with true English pertinacity, for two days, was gradually passing into a drizzle still more unpleasant,—a drizzle that soaked into the already soaked clay, that made the mud more slippery, that penetrated a man's clothing and beat softly but irritatingly against his face, and dripped from his hair and hat down upon his neck, however well he might imagine himself protected by his outside wrappings. ”

“ CHAPTER V DRY-FARM SOILS Important as is the rainfall in making dry-farming successful, it is not more so than the soils of the dry-farms. On a shallow soil, or on one penetrated with gravel streaks, crop failures are probable even under a large rainfall; but a deep soil of uniform texture, unbroken by gravel or hardpan, in which much water may be stored, and which furnishes also an abundance of feeding space for the roots, will yield large crops even under a very small rainfall. ”

“ For instance, in sandy soils, the downward descent of water is very rapid; in clay soils, where the preponderance of fine particles makes minute soil pores, there is considerable hindrance to the descent of water, and it may take weeks or months for equilibrium to be established. It is believed that in a dry-farm district, where the major part of the precipitation comes during winter, the early springtime, before the spring rains come, is the best time for determining the maximum water capacity of a soil. ”

“ But the magnitude of a stream is more especially regulated by the extent of country which forms the declivities of its basin, though there is no invariable proportion here, for a small basin in a humid region will yield a greater quantity of water than one much more considerable in a different situation. High mountains, a humid climate, and a wide superficial drainage, are the three physical circumstances which lead to the accumulation of vast bodies of water, the magnitude of which will be proportionate to the degree in which these causes are in combined operation. ”

“ Most of the soils covering the great dry-farm territory of the United States and other countries have been formed in this way.
In places, glaciers moving slowly down the canons crush and grind into powder the rock over which they pass and deposit it lower down as soils. In other places, where strong winds blow with frequent regularity, sharp soil grains are picked up by the air and hurled against the rocks, which, under this action, are carved into fantastic forms. In still other places, the strong winds carry soil over long distances to be mixed with other soils. ”

“ The so-called capillary soil-water is of greatest importance to the dry-farmer. This is the water that clings as a film around a marble that has been dipped into water. There is a natural attraction between water and nearly all known substances, as is witnessed by the fact that nearly all things may be moistened. The water is held around the marble because the attraction between the marble and the water is greater than the pull of gravity upon the water. The greater the attraction, the thicker the film; the smaller the attraction, the thinner the film will be. ”

“ The dry-farmer, at the outset, should know with comparative accuracy the annual rainfall over the area that he intends to cultivate. He must also have a good acquaintance with the nature of the soil, not only as regards its plant-food content, but as to its power to receive and retain the water from rain and snow. In fact, a knowledge of the soil is indispensable in successful dry-farming. Only by such knowledge of the rainfall and the soil is he able to adapt the principles outlined in this volume to his special needs. ”

“ The sides of each valley are hence equally supplied with moisture, though local circumstances render the soil on one or the other flank more or less humid and favourable to a luxuriant vegetation: such differences are a drier soil on the north side, with a too free exposure to the sun at low elevations, where its rays, however transient, rapidly dry the ground, and where the rains, though very heavy, are of shorter duration, and where, owing to the capacity of the heated air for retaining moisture, day fogs are comparatively rare. ”

“ For this reason dry soils everywhere and most soils in dry climates should, wherever practicable, be left flat. On stiff, heavy soils which are slow to dry out, and on low bottom lands it may be desirable to ridge the land to get the soil dried out and warmed quicker in the spring. ”

“ During the greater part of the year the movement of the waters is partly from the surface downward into the subterranean water courses, from which they emerge in springs; partly by surface drainages into rills, and thence into living streams. By both movements, any tendency to accumulate soluble salts at the surface during the relatively brief periods of dryness is prevented. In a dry country the periods of dryness are very much longer, and the rainfall is seldom sufficient to wash the accumulated salts from the soil. ”

“ In a few cases, ordinary agricultural seeds planted eight inches deep have come up and produced satisfactory plants. However, the consensus of opinion is that from one to three inches are best in humid districts, but that, everything considered, four inches is the best depth under dry-farm conditions. Under a low natural precipitation, where the methods of dry-farming are practiced, it is always safe to plant deeply, for such a practice will develop and strengthen the root system, which is one big step toward successful dry-farming. ”

“ But after any number of days and nights of rain, and in all places exposed to returning sunshine and breezes, the distribution of the moisture tells. So soon as the rain has ceased, all water that can run off is of course gone from the steep hill-sides; there remains only the thin adherent film of moisture to be dried; but that film is spread over a complex texture—all manner of crannies, and bosses, and projections, and filaments of moss and lichen, exposing a vast extent of drying surface to the air. ”

“ Dry Valley cared not. His light blue eyes met Panchita's dark ones with a cold flash in them. He came as far as the gate. He pointed with his long arm to her house.
"Go home," said Dry Valley. "Go home to your mother. I wonder lightnin' don't strike a fool like me. Go home and play in the sand. What business have you got cavortin' around with grown men? ”

“ It is a settled principle of science, as will be more fully discussed later, that the amount of water evaporated from the soil and transpired by plant leaves increases materially with an increase in the average temperature during the growing season, and is much higher under a clear sky and in districts where the atmosphere is dry. Wherever dry-farming is likely to be practiced, a moderately high temperature, a cloudless sky, and a dry atmosphere are the prevailing conditions. ”

“ A common objection to fall plowing is that the ground is so dry in the fall that it does not plow up well, and that the great dry clods of earth do much to injure the physical condition of the soil. It is very doubtful if such an objection is generally valid, especially if the soil is so cropped as to leave a fair margin of moisture in the soil at harvest time. ”

“ The deep valleys are much drier. Each broad expansion of a deep valley is therefore a dry pocket. Into it the sun pours even when all the surrounding hills and mountains are wrapped in cloud. The greater number of hours of sunshine hastens the rate of evaporation and still further increases the dryness. ”

“ It has been estimated that a drained soil has room between its particles for about one quarter of its bulk of water;—that is, four inches of drained soil contains free space enough to receive a rain-fall one inch in depth, and, by the same token, four feet of drained soil can receive twelve inches of rain,—-more than is known to have ever fallen in twenty-four hours, since the deluge, and more than one quarter of the annual rain-fall in the United States. ”

“ The stratified drift in question is situated in a deep depression between two buttresses of rock, and if an enormous glacier be supposed to have once filled the valley of the Tummel to the height of the stratified drift, it may have dammed up the mouth of a mountain torrent by a transverse barrier, giving rise to a deep pond, in which beds of clay and sand brought down by the waters of the torrent were deposited. ”

“ Very high mountain ranges usually consist of many ridges, among which rain-clouds are entangled in their ascent, and in such cases precipitation towards the windward side of the main range, though on the leeward sides of the minor ridges of which it is formed, may occur to so large an extent that before the summit is reached the clouds are exhausted or nearly so, and in this case the total precipitation is less on the leeward than on the windward side of the main range ”

“ In the trade-wind regions of the world, which are characterized by seasons of intense drought, we find rivers carrying a scant and variable amount of water but an abundance of gravel and sand; they are known in different localities as wadis, fiumares and arroyos. Their beds, dry for long periods of the year, become natural roads, paved with the gravel which the stream regularly deposits in the wet season. ”