12 



PRACTICE 5 



Determination of Total Moisture in the Same Soil Under Dif- 

 ferent Conditions. 



Collect samples of surface, subsurface and subsoil* from the fol- 

 lowing places: (1) Sod, (2) Tilled field, (3) Forest. In collecting these 

 samples care should be taken to secure them from as small an area as 

 possible so that soil conditions may be uniform. Expose the samples 

 as little as possible to the air while taking them. After taking them 

 to the laboratory, the contents of the jars should be thoroughly mixed 

 by shaking. The condition of the weather at the time the samples 

 are taken and also the amount of rainfall within the week previous 

 should be noted. 



Make the determinations in duplicate. Weigh 6 soil pans and use 

 100 grams or more of each soil. Weigh rapidly to prevent loss by evap- 

 oration. Place in an oven and leave at least five hours. Cool to the 

 room temperature and weigh at once. The loss of weight represents 

 the total water content. 



It would be well for three students to work together, one taking 

 the surface, another the subsurface, and the third the subsoil. These 

 results may be compared. 



Explain differences in moisture content of the soils. 



PRACTICE 5 



Sod 



Student 



Stratum 



Wt. of 



moist 



soil 



Wt. of 

 water- 

 free-soil 



Loss 



in 

 Grams 



Percent 

 mois- 

 ture 



Surface . . . . 

 Subsurface . 

 1st Subsoil. . 

 2nd Subsoil. 



*In collecting the subsoil for moisture determination it is sometimes well to divide it 

 into two equal parts as to depth. 



