ce in the soil of humus or
vegetable matter contributes also. Yet this latter, as seen in the case
of land heavily dressed with farmyard or stable manure, vegetable
refuse, &c, exercises important functions in other directions. Not only
are mineral constituents, in forms available for assimilation, supplied,
but soils so treated derive peculiar advantages as regards their
mechanical state and improved physical conditions, chiefly in respect of
retention of moisture, warmth, &c. Thus, sandy soils, which are very
apt, through poverty in humus, to lose their moisture readily and to
'burn,' are rendered more retentive of moisture and fertilising
constituents by the use of farmyard manure, &c., and have more 'staple'
or substance given to them, while heavy, tenacious clays are opened out,
lightened, and rendered more amenable to the influences of drainage,
aeration, &c., and so become less cold and inactive.

For the present purpose the principal garden crops may be grouped in two
classes, in accordance with their main characteristics and the
predominance of certain of their mineral elements. The figures given on
the following page show the average percentage proportions of the
several minerals in the ashes of the different plants.

In Class I. Phosphates and Potash predominate. This class consists of
the less succulent plants, and includes the following: The Pea:
containing, in 100 parts of the ashes, phosphates, thirty-six; potash,
forty. Bean: phosphates, thirty; potash, forty-four. Potato (tubers
only): phosphates, nineteen; potash, fifty-nine; soda, two; lime, two;
sulphuric acid, six. Parsnip: phosphates, eighteen; potash, thirty-six;
lime, eleven; salt, five. Carrot: phosphates, twelve; potash,
thirty-six; soda, thirteen; sulphuric acid, six. Jerusalem Artichoke:
phosphates, sixteen; potash, sixty-five.

In Class II. Sulphur, Lime and Soda Salts are predominant. This class
consists of the more succulent plants, and includes the following:
Cabbage: containing, in 100 parts of the ashes, phosphates, sixteen;
potash, forty-eight; soda, four; lime, fifteen; sulphuric acid, eight.
Turnip: phosphates, thirteen; potash, thirty-nine; soda, five; lime,
ten; sulphuric acid, fourteen. Beet: phosphates, fourteen; potash,
forty-nine; soda, nineteen; lime, six; sulphuric acid, five.

As a matter of course, Lentils and other kinds of pulse agree more or
less with Peas and Beans in the predominance of phosphates and potash.
So, a