72 VEGETABLE FORCING 
manure must be well decayed so that it will be short and 
fine before the soil is used for forcing purposes. (2) The 
fiber must be thoroughly mixed with or incorporated 
throughout the mass of soil. (3) The soil must be thor- 
oughly saturated with the liquid of the manure. To 
accomplish these results it is necessary to start compost- 
ing well in advance of the time when the soil will be 
wanted for use in the greenhouse. The actual length of 
time required to make a good compost depends upon the 
character of the soil as well as upon the manure. If the 
soil is heavy and the manure fresh and coarse, much 
more time will be needed than if the soil is light and the 
manure old and of fine texture. The time required for 
composting also depends upon the method employed. 
One of the oldest and most satisfactory methods is to 
stack manure and sods in alternate layers. The piles are 
generally 4 or 5 feet deep and large enough to meet the 
needs of the house. Thick, heavy clover and grass sods 
are preferable. They may be cut with spades and hoes, 
or more rapidly with a plow set to run very shallow, and 
then cut across the thin furrow slices with a spade or an 
old axe. The sods and manure are hauled and stacked 
as near to the greenhouse as possible, so that the com- 
posted materials may be placed in the greenhouse with- 
out further hauling or unnecessary handling. The 
relative thickness of the alternate layers of manure and 
compost should be determined mainly by the character 
of the soil used. More manure is needed for the heavier 
soils than for the lighter types. When the sods are 
grown in silt and clay soils, the layers of manure and 
sods should be of about equal thickness, and they may 
range from 10 to 15 inches. 
In sandy soils the layers of manure may be several 
inches less in thickness than the sods; 10 inches of 
manure and 14 inches of soil give excellent results. 
Compost piles of this character should be started at least 
