. Soils and fertilizers . SOIL WATER 87 Exercise IV. — Water-holding capacity of soils. Materials. — Same as in Exercise III. Procedure. — When Exercise III is complete, cover chimneys andallow all the free water to drain away. Then weigh the chimneysand wet soil. The increased weight is water retained. Calculatethe percentage of water retained by each soil based on the weightof the original sample. Write out a full description of the experiment and the pointsof importance that it shows. Exercise V. — Moisture conservation by means of a soil mulch. Materials. — Three tumblers, one of which sho
. Soils and fertilizers . SOIL WATER 87 Exercise IV. — Water-holding capacity of soils. Materials. — Same as in Exercise III. Procedure. — When Exercise III is complete, cover chimneys andallow all the free water to drain away. Then weigh the chimneysand wet soil. The increased weight is water retained. Calculatethe percentage of water retained by each soil based on the weightof the original sample. Write out a full description of the experiment and the pointsof importance that it shows. Exercise V. — Moisture conservation by means of a soil mulch. Materials. — Three tumblers, one of which should be one inchshorter than the other two, moist soil, dry clay loam and dry sand,torsion balance. Procedure. — Fill the short tumbler level full with a well-mixedmoist soil. This is to serve as the unmulched treatment. Place CLAY LOAM MULCH 5AMDY LOAM MULCH MULCH I. MOI5T50IL M0I5T SOIL M0I&T50IL Fig. 18. — Tumblers filled with equal quantities of a moist soil and pre-pared for a demonstration of the effectiveness of mulches in the conserva-tion of moisture. Losses of moisture by evaporation are measured by weigh-ing the tumblers. exactly the same amount of moist soil in each of the other tumblersas is used in the shorter one, compacting to within one inch of the the surface of one place one inch of dry clay loam and on theother one inch of dry sand. Weigh the tumblers now fully prepared. Set tumblers in a place of uniform temperature and weigh dailyfor a week. The loss of weight each day is moisture. Tabulatedata and draw curves. Explain the significance of the results obtained. 88 SOILS AND FERTILIZERS Exercise VI. — Loss of water by — Glazed gallon butter jar, oats seed, paraffined paper,thistle tube, coarse sand and heavy balance. Procedure. — Fill a glazed jar with rich soil, first adjusting coarse
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