Soils and fertilizers . ight of the sands, will give theweight of the silt and clay. Calculate the percentages of sand andof silt and clay respectively in the sample of sandy loam. Exercise IV. — Study of soil class and its determination byexamination. Materials. — Hand lens, a number of different soil classes (sand,sandy loam, clay loam, loam, silt loam, muck, etc.) labeled for studyand a set of unknown specimens for identification. TEXTURE AND STRUCTURE OF SOILS 47 Procedure. — Examine the texture of each of the labeled soilsboth under the hand lens and by the feel. Observe the color andesti
Soils and fertilizers . ight of the sands, will give theweight of the silt and clay. Calculate the percentages of sand andof silt and clay respectively in the sample of sandy loam. Exercise IV. — Study of soil class and its determination byexamination. Materials. — Hand lens, a number of different soil classes (sand,sandy loam, clay loam, loam, silt loam, muck, etc.) labeled for studyand a set of unknown specimens for identification. TEXTURE AND STRUCTURE OF SOILS 47 Procedure. — Examine the texture of each of the labeled soilsboth under the hand lens and by the feel. Observe the color andestimate the amounts of organic matter by the darkness of the able to identify samples if unlabeled. Observe the plasticity and cohesion of each soil when enoughwater has been added to develop maximum plasticity. Make smaUmarbles of sand, clay and muck respectively when each is at itsmaximum plasticity. Dry and observe relative cohesion andplasticity. Be able to state the relation of texture, moisture and or-. f\PPflRftTU5 nUIRIHe SftNDS Fig. 7. -Apparatus for a simple mechanical analysis of soil,bottle, funnel, filter, beaker and stand. Shaker ganic matter to cohesion and plasticity. What is the practical im-portance of texture and class ? Obtain set of unlabeled samples for identification of class. Ifpossible, pupils should also identify samples in the field. As mois-ture variations and tillage operations often make great differencesin the general appearance of a soil, skill in quickly and accuratelydetermining the class of any soil in the field is a valuable asset inall agricultural work. Exercise V. — Determination of soil class from a mechanicalanalysis. Materials. — Figure on page 35. 48 SOILS AND FERTILIZERS Procedure. — By the use of the chart determine the class of thefollowing soils and describe their probable characteristics. Soil FineGravel COAHSE Sand MediumSand FineSand VertFineSand Silt Clay 1 1 5 6 5 3 70 10 2. 2 3 10 18 12 45 10 3 1 2 14 18 25
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