Soot is the volatilized unconsumed portion of common coal. It is thus constituted: -

It is an excellent manure for peas, onions, carrots, and probably all garden crops. An excellent liquid manure is soot mixed with rain water, in the proportion of one tablespoonful of soot to a quart of water, for plants in pots; but for asparagus, peas, etc, six quarts of soot to a hogshead of water. It must never be applied to plants in a state of rest. It succeeds admirably with bulbs. - Gard. Chron.