Productive farming . pact soilduring a heavy rain? Exercise.—To Illustrate Capillarity.—Place one end ofan old loose cloth in a cup of water and leave the other endoutside. In a short time the whole cloth may become wetby capillarity. The water moves along in the fine meshesof cloth. Oil is drawn up in a lamp through the wick by theforce of capillarity. 62 PRODUCTIVE FARMING Exercise. — To Show Capillarity in Soils. — Tie clothover the large ends of lamp chimneys and fill with differentkinds of dry soils, as shown in Fig. 35. Set them in a dishof water. The water will rise in the feoils by cap
Productive farming . pact soilduring a heavy rain? Exercise.—To Illustrate Capillarity.—Place one end ofan old loose cloth in a cup of water and leave the other endoutside. In a short time the whole cloth may become wetby capillarity. The water moves along in the fine meshesof cloth. Oil is drawn up in a lamp through the wick by theforce of capillarity. 62 PRODUCTIVE FARMING Exercise. — To Show Capillarity in Soils. — Tie clothover the large ends of lamp chimneys and fill with differentkinds of dry soils, as shown in Fig. 35. Set them in a dishof water. The water will rise in the feoils by capillarity. Itwill rise much higher in the finer soils such as clay and rises quickly but not so high in coarse land. Increasing Soil Moisture.—Since humus holds so muchcapillary water, the farmer has one sure way to increase thewater-holding power of any soil. The addition of greenmanure and barn manure will cause humus to form in thesoil. Large quantities of humus will hold more moisture in ^%. Fig. 35.—^Water rises more rapidly by capillarity through fine soilsthan in coarse soil. the capillary form and thus encourage the growth of largercrops. Deep plowing will increase the depth of the waterreservoir. Harrowing and cultivating will help, becausethe more a soil is stirred the less water it will lose by evapo-ration. Furthermore, rains sink into a loose surface betterthan into a hard compact one. Underdrainage of soils willincrease this power to hold capillary moisture, because thevolume of soil above the free water level is made greater. How to Save Soil Moisture.—Spaces between soil grainsserve as very crooked small tubes to conduct the lower soilwater toward the surface. Harrowing and cultivating the SOIL MOISTURE 63 surface of the soil -will break the connection of the spaces orpores with each other. If this capillary connection is brokennear the surface the moisture will be checked in its upwardmovement and be held near the roots. The covering
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