.

For the above reasons potash manures ought to be applied to the soil a
considerable period before they are likely to be used by the crop. There
is little risk of any serious loss taking place owing to rain. Autumn
application is generally recommended. Even in very light soils it has
been proved in the Norfolk experiments that autumn application has an
immense advantage over spring application. It has been found that where
potash is applied as sulphate, little sulphuric acid is absorbed by the
plant.

_Soils and Crops suited for Potash Manures._

Of soils best suited for potash manures, it has been found that light
soils, and those largely charged with peaty organic matter (such as the
moorland soils of Germany), are most benefited; while on heavy clayey
soils the percentage of potash which these latter contain is already
sufficiently abundant for the needs of plants. At Flitcham the value of
potash on chalk soils has been strikingly demonstrated. Of crops, it is
now pretty generally acknowledged that those of the leguminous order are
most benefited by potash. Especially in the case of clover has potash
always proved itself a manure worth applying.

_Rate of Application._

Potash is best applied in small quantities. From 1 to 2 cwt. of the
muriate or sulphate is a common amount, and from 6 to 8 cwt. of kainit.

CHAPTER XVI.

MINOR ARTIFICIAL MANURES.

In addition to the manures which have been discussed in previous
chapters, there are a number of minor manures which are used to a very
much smaller extent--dried blood, hoofs, horns, &c.

Among these one of the most valuable is dried blood. Fresh blood,
containing 80 per cent of water, has from 2.5 to 3 per cent of nitrogen,
about .25 per cent of phosphoric acid, and about .5 per cent of
alkalies. When dried it forms a very concentrated and valuable
nitrogenous manure, which has long been used in France. The commercial
article contains, on an average, about 12 per cent of nitrogen, and
slightly over 1 per cent of phosphoric acid. When mixed with the soil it
ferments, and the nitrogen it contains is converted into ammonia.
Although not so quick-acting a manure as nitrate of soda or sulphate of
ammonia, it can by no means be described, as is done in ordinary
agricultural text-books, as a slow-acting manure. Its nitrogen may be
regarded as of equal value to that in Peruvian guano. It is peculiarly
suited for horticulture, and is chiefly used in this