PLANT 
59 NEEDS 
lime, stable manure, green manure, clover and 
cowpeas to doctor the soil with, when it is 
suffering from chemical ills. This gives some 
idea of the vast unexplored regions of agriculture 
which afford you and every other worker in 
the soil an opportunity to make some great 
discovery for the benefit of the world. No other 
calling offers such limitless opportunities. 
Lime is especially valuable for plant food 
and also to make other kinds of plant food 
available. Crops often fail in soil where there 
is plenty. of plant food, because it is not in the 
form that the plants can use. Lime hastens the 
decay of vegetable matter, sweetens sour soil, 
and greatly improves the texture of clay soils. 
Besides this it counteracts magnesium in the soil 
and destroys its bad effects. But lime may not 
be applied carelessly, because, although some 
plants cannot live without it, some require a 
very small quantity. (It is, therefore, wise to 
send a sample of the soil, to write what we want 
to grow, to the nearest Government experiment 
station, who will probably suggest what could 
be done with it, to make it productive.) 
The right degree of warmth is another plant 
necessity. The best temperature for plants 
generally is 86° of the ordinary thermometer 
(30° Centigrade). This, however, depends upon 
