84 VEGETABLE FORCING 
proper amount of lime for greenhouse soils. One pound 
of unslaked stone lime is considered sufficient for 20 
square feet of space, and double that amount will do no 
harm. It should be scattered evenly over the surface and 
thoroughly mixed with the soil. See page 64 relating 
to the functions of lime. 
Applying fertilizers—When commercial fertilizers are 
employed they are usually applied after plowing or 
spading and mixed with the soil by subsequent harrow- 
ing or raking. Nitrate of soda is often used as a top- 
dressing, applied either in dry or liquid form. Excessive 
amounts of fertilizers may cause curling, wrinkling or 
burning of the leaves. About % ton to the acre of 
mixed mineral forms of commercial fertilizers is probably 
as much as can be used with safety on any of our green- 
house crops. One ounce of nitrate of soda to each gallon 
of water may be applied to lettuce and other crops with- 
out danger of injury unless the soil already contains a 
large amount of mineral fertilizers. For more specific 
information, see the discussion of fertilizers in connection 
with each class of vegetables. 
