Grade. 

 Date. . 



(30) 



EXERCISE 9 



Effects of Organic Matter 

 Purpose. — To study the effects of organic matter in soils. 



Secure directions from the instructor in charge as to where the samples 

 of soil shall be taken, — one from a plot rather free from organic matter, 

 the other from sod land or soil otherwise rich in organic matter. 



Take steel cylinder (Fig. 5), a heavy block of wood and an axe or hammer. 

 Select a place as free from stones as possible in the cultivated ground. 

 Carefully drive cylinder into the earth to a depth of seven inches. Dig 

 out around it with a spade and remove. Transfer the soil from within 

 the cylinder to an oilcloth or paper and from there to a glass jar. (In 

 lieu of the cylinder method, samples may be taken with a spade. Equal 

 volumes may be compared by measurement in tubes or cans filled and 

 packed equally.) 



Repeat the same process in the sod land. 



Bring the samples of soil to the laboratory and weigh each carefully. 



Weigh out 100 grams of each soil and determine the amount of capillary 

 water in each. 



Make the following calculations, using the entire samples, or equal volumes 

 of each. 



Weight of Apparent 



furrow slice sp. gr. 



Per cent, of 

 capillary water 



Cultivated . 



Sod. 



QUESTIONS 



Describe the color and physical appearance of the two soils. 

 Which weighs the more and why? 

 Which do you think would retain the more water? 

 Which soil has the greater apparent specific gravity? Why? 

 Which soil has the greater porosity? Why? 

 Which soil would the farmer consider the more productive? 

 State clearly the influence of constant tillage upon the organic matter in 

 the soil. 



