234 SOILS AND FERTILIZERS 



Exercise III. — The value of manure on the home-farm. 



From the data in the text, have each student calculate the 

 probable quantity of manure produced on his home-farm. Have 

 him calculate the commercial value of this manure. Then from the 

 way in which the manure is handled have him estimate the loss 

 which occurs to this manure. Now discuss the probable agricultural 

 value of the manure as compared with its original commercial value. 



Exercise IV. — Reinforcement of farm manure. 



In cooperation with some near-by farmer, reinforce some farm 

 manure, allowing the pupils to aid not only in the actual work, but 

 in the determination of the kind and amount of reinforcing materials 

 to use. Calculate from the quantities used and their composition 

 as given in the text, the probable composition of the manure after 

 the treatment and determine whether it has become a properly 

 balanced material. The reinforced manure should be spread in 

 the field so that its influence on the succeeding crop may be com- 

 pared with untreated manure. Reinforcements with different ma- 

 terials may even be compared under actual field conditions. 



Exercise V. — Building of a compost pile. 



Farm manure in a compost pile supplies the organisms which 

 bring about the decay of the sod, leaves or other plant materials 

 which are to be reduced to simple compounds. Composted mate- 

 rials are of especial value in greenhouses and gardens in supplying 

 organic matter to the soil, that a good structure may be maintained. 



Choose a level spot on which to locate the compost pile. First 

 put down a layer of sod, moistening if necessary until optimum con- 

 ditions are attained. Next apply a thin layer of fine, well-rotted 

 manure, then sod and so on till the pile is complete. The pile may 

 be as large as necessary or convenient and should be level on top to 

 prevent the rainfall from running off the surface. If the interior of 

 the pile is moist to begin with, it will stay moist through the period 

 given to fermentation. Six months or a year are necessary for 

 effective composting. 



Other materials than sod may be placed in a compost heap, 

 such as leaves, vines of all kinds, rotted vegetables, garbage, small 

 sticks, etc. It is a good practice also to add lime to the pile to keep 

 it sweet. If the material is to be used as a fertilizer as well as to 

 condition the soil, acid phosphate may also be added. 



