EXERCISE 70 



HOW MUCH WATER MAY BE HELD BY SOIL? 



Materials. Glass dishes ; balances ; drying oven, radiator, or stove ; soil. 



Directions. For this exercise soil should be used which is directly from out of doors. Weigh a 

 small dish, fill it with the soil, and weigh again. Set the dish in a dry, warm place and weigh at 

 intervals as long as the soil continues to lose water as indicated by a decrease in weight. At the 

 last it should be placed in a drying oven at a temperature slightly above the boiling point. If an 

 oven is not available, a radiator or stove may be used, but the results will not be so accurate. 

 Tabulate your results as follows: 



Save the soil and keep it dry for a later experiment. Note that the percentages in this and the 

 following exercises are all calculated with reference to dry soil. 



Additional problems. Take samples of soil from the first 2 inches of the surface, from a depth of from 6 

 to 8 inches, and from a depth of from 14 to 16 inches. Determine the relative percentages of water in soil 

 at the different depths. 



Saturate a soil with water ; then determine what percentage of water it contains. 



When a plant wilts because it cannot longer secure water from the soil, is the soil perfectly dry ? 



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