rally rich in potash, sulphur, and phosphates, but
deficient in soluble silica and lime. Limestone and chalk are usually
rich in lime and phosphates, but deficient in humus, silica, sulphur,
and alkalies. Sandy soils are rich in silica, but are generally poor in
respect of phosphates and alkalies. Therefore, on a clay or loam,
farmyard manure is invaluable, because it contains ingredients that all
crops appreciate, and also because it is helpful in breaking up the
texture of the soil. The occasional application of lime also is
important for its almost magical effect on garden soil that has been
liberally manured and heavily cropped for a long term of years.
Calcareous soils are greatly benefited by a free application to them of
manure from the stable and cow-byre; but as a rule it would be like
carrying coals to Newcastle to dress these soils with lime. Clay may be
put on with advantage; and nothing benefits a hot chalky soil more than
a good dose of mud from ponds and ditches, which supplies at once humus,
alumina, and silicates, and gives 'staple' to the soil, while
preventing it also from 'burning.' In the manuring of sandy soils great
care is requisite, because of their absorbing power. In the bulb-growing
districts of Holland, manure from cowsheds is worth an enormous price
for digging into loose sand for a crop of Potatoes, to be followed by
bulbs. Sandy soils are generally deficient in phosphates and alkalies;
hence it will on such soils be frequently found that kainit (a crude
form of potash) and superphosphate of lime will conjointly produce the
best results, more especially in raising Potatoes, Onions, and Carrots,
which are particularly well adapted for sandy soils. Probably one of the
best fertilisers is genuine farmyard manure from stall-fed cattle, for
it contains phosphates, alkalies, and silicates in available forms. For
similar reasons Peruvian Guano is often useful on such soils. Artificial
manure should be selected with a view to correct the deficiencies of the
soil, and to satisfy the requirements of the crops to be grown on it.

While we have thus dealt principally with the Inorganic or mineral
constituents of plants, and the way in which the deficiencies of the
soil in respect of any of them may be supplied by artificial
applications, we must not ignore the other class of constituents, the
Organic. These are supplied almost entirely from the atmosphere itself,
though, to a limited extent, the presen