_potash_.

5. That the best results can be expected only when the liquid and solid
excreta are used together as a manure.

As the composition of the manure depends so largely on the nature of the
food, a table will be found in the Appendix, Note VI.,[142] containing
the manurial composition of some of the commoner feeding-stuffs.

3. _Litter._

We have now to consider the third constituent of farmyard manure--viz.,
the _litter_, which generally consists of straw.

The uses of the litter, in addition to providing a dry and comfortable
bed for the animal, may be briefly summed up as follows:--

1. To absorb and retain the liquid portion of the excreta.

2. To increase the quantity of the manure, and thus secure its more
equal distribution when applied to the field than could otherwise be
done.

3. To add to its value as a manure, both physically and chemically.

4. To retard and regulate the decomposition of the excreta.

Of course litter also performs a very useful function sanitarily,
inasmuch as it serves to keep the stall or byre fresher and cleaner, and
more free from noxious gases, which it absorbs, than would otherwise be
the case.

_Straw_ is almost universally used for this purpose. Besides being one
of the bye-products of the farm, it is admirably suited in many ways,
both owing to its peculiar shape--its tubular structure being
excellently adapted for this purpose--as well as on account of its
composition, being largely composed of cellulose, a very absorptive
substance. Straw thus possesses considerable absorptive power. In
manurial ingredients it is not very rich; for, of the various parts of
the ripened plant, straw contains the least percentage of nitrogen and
phosphates. This is due to the fact that, as the straw ripens, a
considerable proportion of these ingredients passes up from the stalk to
the seeds, where they are retained.

Generally speaking, straw may be said to contain not more than _a half
per cent_ of nitrogen--_i.e._, 11.2 lb. per ton. Its percentage of
nitrogen varies, of course; the recorded analyses[143] for wheat-straw
ranging from .22 to .81 per cent, or furnishing an average of .48 per
cent--_i.e._, 10.75 lb. per ton. Barley-straw is somewhat richer in
nitrogen, the recorded analyses ranging from .41 to .85 per cent, or
giving an average of .57 per cent--_i.e._, 12.76 lb. per ton; while
oat-straw is the richest of the commoner straws, ranging from .32 to
1.12 per cent, a