Rural School Leaflet. ()53 



Compare the sand, silt, and clay as to origin, color, size of particles, 

 and stickiness. Do you find any more humus in one sample than in 

 another? 



Rubbing the soil between your fingers will help you to compare the 

 size of the particles. Bring out the fact that the particles of sand are 

 not only large but also angular; that the particles of humus may be the 

 finest, and when rubbed between the fingers give a velvety sensation. 

 Place some humus soil on a hot stove and notice how it burns. The 

 sand and clay will not burn. The clay particles are fine. This gives the 

 soft, oily feeling when the particles are rubbed between the fingers. 

 The particles which are between the clay and sand in size are called 

 silt and also have a soft feeling. 



Squeeze some of each of the soils in your hand, then notice which 

 falls apart when you open your hand. The soil which remains in a 

 compact mass when you open your hand is the most sticky. Separate 

 the soil into very sticky (clay), slightly sticky (silt), and not sticky 

 (sandl. 



Which soil ought not to be worked while it is wet? Why? With 

 which soil would it not make any diflference? 



Name the material in our soils coarser than sand. 



Bring out the fact that sand can be detected by its large particles, 

 clay by its stickiness, and humus by the fact that it will burn. 



Subject matter. — Our farm soils are composed of stones, gravel, sand, 

 silt, clay, and humus. All the particles above 1-25" (i mm.) in diameter, 

 are considered either stones or gravel. Sand includes all the par- 

 ticles betvveen 1-25" and 1-500" (i mm. to .05 mm.) in diameter, ranging 

 from coarse sand to very fine sand. Silt includes all particles between 

 1-500" and 1-5000" (.05 mm. to .005 mm.) in size. Clay includes all 

 particles between 1-5000" and 000. (.005 mm. to .0000 mm.) in diameter. 

 These fine measurements of the sand and clay have been computed by 

 the use of a microscope, and are standard. Humus varies from visible 

 fragments of woody tissue and pieces of twigs to a black powdery 

 material. 



The different proportions of these ingredients give us our various farm 

 soils. If sand predominates, we have a sandy soil; if clay, a clay 

 soil; and if humus, we have a muck. A loam is a mixture of sand, silt, 

 clay, and a little humus. A sandy loam contains more sand than clay, 

 a clay loam more clay than sand, and a gravelly loam is one con- 

 taining a very noticeable amount of gravel. As far as possible have 

 the pupils bring in different samples of the above soils. Discuss with 

 them the way in which soils are adapted to certain crops. 



