PRACTICE 1 

 Determination of Capillary Moisture* in Soils. 



Use soils collected according to method given belowf and make 

 the determinations in duplicate for surface, subsurface and subsoil. 

 Weigh carefully six soil pans. Place in each from 100 to 200 

 grams of the soil and weigh pan and soil quickly to prevent loss of 

 moisture. Let it dry at room temperature for 72 hours, after which 

 weigh at intervals of about 24 hours till a practically constant weight 

 is obtained. The loss of weight is the capillary moisture. Express 

 your results in grams, and after the completion of the next exercise 

 express the results in percent of the water-free soil. Use these air-dry 

 soils for Practice 2. 



Express in tabular form the capillary moisture in grams and per- 

 cent of water-free soil. 



*The moisture content will always be expressed as percent of the water-free soil 

 in these exercises unless otherwise stated. 



tFor this practice and also for Practice 5 the students are required to collect their 

 own samples. For this purpose a one and one-half inch or a two-inch auger with an 

 extension making it 40 inches long is used. In collecting samples for moisture determin- 

 ations, expose the soil as little as possible to the air before putting in jars. Collect the 

 surface soil to the depth of the plow line, usually about 7 inches. After this part of the 

 sample is removed, the hole is enlarged sufficiently so that the subsurface soil may be 

 taken without coming in contact with the surface soil. Take the subsurface sample to 

 the subsoil line as indicated by the change in color, texture and physical composition. 

 Commonly this line is found at a depth of 16 to20 inches, Enlarge and clean out the hole as 

 before. Since the change from subsurface to subsoil is not a sharp line but usually 

 somewhat gradual, we discard about two inches of the intermediate mixture. The sub- 

 soil is then collected to a depth of 40 inches, if possible. 



In some soils the subsurface layer may be absent, the subsoil being reached by 

 the plow, while in others, as in peaty and sandy soils, no true subsoil may be found 

 within 40 inches of the surface. In such cases only two samples are taken. 



