66 Gardening 
Compost may be made also from the vegetable wastes 
of the kitchen that decay readily, from weeds, grass 
clippings from the lawn, leaves in autumn, and other 
vegetable matter of any kind. These should all be 
saved and composted either with manure or separately. 
Good compost is very valuable in forcing and growing 
transplanted seedlings in flats in greenhouses, hotbeds, 
and cold frames, as well as for enriching the soil of the 
garden! Every garden should have a compost pile. 
Care should be taken not to add to compost diseased or 
insect-infested plants, for this may facilitate the spread 
of fungous diseases or insect pests. 
Commercial fertilizers. A commercial fertilizer fur- 
nishes for the use of plants nitrogen, phosphorus, and 
potassium. Nitrogen is usually obtained in sodium 
nitrate, ammonium sulfate, and in “tankage” (the 
refuse of slaughterhouses). Phosphorus is usually ob- 
tained from tankage and from acid phosphate, which 
is made by treating rock containing phosphates with 
sulfuric acid. Potassium is obtained mostly from potas- 
sium sulfate and potassium chlorid, both of which are 
mined from the earth. 
A fertilizer that supplies all of the three elements, 
nitrogen, phosphorus, and potassium, is called a “‘ com- 
plete ” or “ general” fertilizer; one that supplies only 
one or two of these is called an “ incomplete ” or “ spe- 
cial” fertilizer. 
A good general fertilizer for garden crops should 
contain in a form that plants can use, by guaranteed 
1 Compost should not be used for seed beds or in seed pans,.as it is 
too rich for young seedlings. 
