eta. In the
case of a man it has been estimated that the urine voided is fifteen
times as much, is twelve times as rich in nitrogen, three times in
potash, and two in phosphoric acid, as the solid excreta (Munro). The
relation of solid matter in the case of the farm animals is not exactly
similar. The urine of the ox is about twice the weight of its solid
excreta. Both the horse and the sheep, however, void as a rule more
solid excreta than urine. Munro, in his work on 'Soils and Manures,'
contrasts the composition of the urine and solid excreta of the
different farm animals by the following statement:--

1 ton of urine contains 1 ton of solid excreta
in lb.: contains in lb.:

Nitrogen. Potash. Nitrogen.
Cow 30 20 9
Horse 36 22 12
Sheep 38 30 16

FOOTNOTES:

[181] Storer's 'Agricultural Chemistry,' vol. I. p. 496.

[182] Scott's 'Manures and Manuring,' p. 19.

CHAPTER VIII.

GUANO.

_Importance in Agriculture._

In the consideration of _artificial_ manures, guano deserves the first
place. This it does mainly on historical grounds, as it is now largely a
manure of the past. Not merely has it been used in agriculture to an
extent to which no other artificial manure has as yet ever approximated,
but its influence on agricultural practice has been enormous. Introduced
into this country about the middle of the present century, it was the
first of artificial manures to be used in large quantities.[183] It may
be thus described as having introduced the modern system of _intensive_
cultivation, and given rise to the now almost universal practice of
artificial manuring.

_Influence on British Farming._

It is, indeed, difficult to over-estimate the important influence which
the introduction of this most valuable fertiliser has exercised on
British as well as, to a large extent, on European husbandry. Before its
introduction the farmer was almost completely dependent on his farmyard
manure. He was tied down to a great extent, by the exigencies of the
then prevailing agricultural customs, to certain rotations of crops. He
could do little in the way of enriching barren soils or of ensuring a
heavy yield of crop. By the use of this very potent fertiliser, he
quickly discovered that the most wonderful results ensued--results which
must have seemed