| OCR Text |
Show FORMATION OF ALKALI SPOTS Saline Incrustation Upon Surface of j . Soli Hinders Vegetation and I Annoys the Farmer. I It appears that within the past number num-ber of years more than ever before a phenomenon, resulting unquestionably unquestion-ably from the dry summers and rather rath-er moist springs and falls, in different differ-ent sections of the Middle Northwest, has come under the observation of the farmers. It Is a saline Incrustation upon the Burface of the soil. It hinders vegetable vege-table growth, and causeB annoyance to the farmer wherever such spots are found. The alkali spots sometimes some-times appear of light whitish gray color, and form a narrow ring on the outer edge where the water and land seem to touch or meet, In a pond or mud puddle. This happens where the land is low, the soli rich in plant food j and the soil In need of drainage. Alkali spots are prevalent in our western states, particularly In the arid regions. They are caused principally prin-cipally by the capillary movement of soil water which comes from lower zones of soil, and contains in solution saline and soluble matters necessary neces-sary to the growth of the plant. The alkali spots are more in evidence in the late summer in times of drought, and when the evaporation of moisture moist-ure from the surface of the soil exceeds ex-ceeds the amount of rainfall and the percolation of water In the soil. The upward capillary movement of moisture is very slow. It is incessant so long as there is any out-go of water from the upper layers of the soil either through mere evaporation or by force of exhalation of water by the growing plants. Capillary movement move-ment acts with equal density by day and by night. The evaporation of water from the surface of the land will usually be largest during the day when the sun Is shining on the soil and on the plants that are growing on it. During the night when the evaporation is checked, the capillary movement within with-in the soil still goes on, and has in so far better opportunity to supply moisture from- below to make good what has been lost from the surface during the preceding day. When a sheet of water stands over a field and there is no capillary movement there, the physical forces In the soil under such condition are practically at a standstill. But when water is removed and the pore space In the soil becomes open and to a degree de-gree free from water, evaporation from surface of soil takes place and capillary begins to act. The salts at the Burface are brought up but not evaporated like moisture would be. It Is this action that gives rise to the accumulation of salts near surface sur-face of soil in wet fields. |
