It has just been said that lime causes the pulverization of the particles of the soil; and thus, by making it finer, improves its mechanical condition.
Some mineral manures, as plaster and salt, have the power of absorbing moisture from the atmosphere; and this is a mechanical improvement to dry soils.
Name some mineral manures which absorb ammonia?
4th. Those mineral manures which have the power of absorbing ammonia.
Plaster, chloride of lime, alumina (clay), etc., are large absorbents of ammonia, whether arising from the fermentation of animal manures or washed down from the atmosphere by rains. The ammonia thus absorbed is of course very important in the vegetation of crops.
Having now explained the reasons why mineral manures are necessary, and the manner in which they produce their effects, we will proceed to examine the various deficiencies of soils and the character of many kinds of this class of fertilizers.
CHAPTER IX.
DEFICIENCIES OF SOILS, MEANS OF RESTORATION, ETC.
As will be seen by referring to the analyses of soils on p. 72, they may be deficient in certain ingredients, which it is the object of mineral manures to supply. These we will take up in order, and endeavor to show in a simple manner the best means of managing them in practical farming.