MOULD, in Agriculture, a general name for the soft earthy substance with which the dry land is generally covered, and in which all kinds of vegetables take root and grow. It is far from being an homogeneous substance; being composed of decayed animal and vegetable matters, along with calcareous, argillaceous, and siliceous earths, mixed together in various proportions, and with the different degrees of moisture, constituting every variety of SOIL.