THE 
GARDEN YARD 252 
of lime, which, although insoluble, readily be- 
comes available as plant food in the soil. 
Potassium occurs in various forms of com- 
bination, one of the most common being muriate 
of potash; another form is sulphate of potash. 
Kainit is another fertilizer which contains 
potassium, and wood ashes contain a small 
percentage. In all of these the potassium is 
generally spoken of as potash and the first two 
are said to contain the equivalent of 50 per cent. 
potash. Kainit usually contains 12 to 14 per 
cent. Wood ashes may contain about 3 to 6 
per cent. Kainit and muriate of potash have 
an acid effect upon the soil, and it is wise to 
apply them some time before the crop is to be 
sown, even the fall previous, if the soil retains 
plant food fairly well. 
The commonest kind of calcium is quick- 
lime or lump lime. When this is “air- 
slaked”’ it becomes what is called carbonate of 
lime. Fifty-six pounds of lump lime contain 
the same amount of calcium as 100 pounds of 
air-slaked lime, and in using these it makes very 
little difference whether we apply the quick- 
lime or the air-slaked, provided we apply equal 
amounts of calcium and that the particles are 
equally small in both cases. In other words, 
56 pounds of quick-lime or 100 pounds of air- 
