nged into
plant-food; more especially, in other words, in order that the crude
nitrogenous organic matter in the clover-roots and decaying leaves, may
have time to become transformed into ammoniacal compounds, and these, in
the course of time, into nitrates, which I am strongly inclined to think
is the form in which nitrogen is assimilated, par excellence by cereal
crops, and in which, at all events, it is more efficacious than in any
other state of combination wherein it may be used as a fertilizer.

"When the clover-lay is plowed up early, the decay of the clover is
sufficiently advanced by the time the young wheat-plant stands in need
of readily available nitrogenous food, and this being uniformly
distributed through the whole of the cultivated soil, is ready to
benefit every single plant. This equal and abundant distribution of
food, peculiarly valuable to cereals, is a great advantage, and speaks
strongly in favor of clover as a preparatory crop for wheat.

"Nitrate of soda, an excellent spring top-dressing for wheat and cereals
in general, in some seasons fails to produce as good an effect as in
others. In very dry springs, the rainfall is not sufficient to wash it
properly into the soil and to distribute it equally, and in very wet
seasons it is apt to be washed either into the drains or into a stratum
of the soil not accessible to the roots of the young wheat. As,
therefore, the character of the approaching season can not usually be
predicted, the application of nitrate of soda to wheat is always
attended with more or less uncertainty.

"The case is different, when a good crop of clover-hay has been obtained
from the land on which wheat is intended to be grown afterwards. An
enormous quantity of nitrogenous organic matter, as we have seen, is
left in the land after the removal of the clover-crop; and these remains
gradually decay and furnish ammonia, which at first and during the
colder months of the year, is retained by the well known absorbing
properties which all good wheat-soils possess. In spring, when warmer
weather sets in, and the wheat begins to make a push, these ammonia
compounds in the soil are by degrees oxidized into nitrates; and as this
change into food peculiarly favorable to young cereal plants, proceeds
slowly but steadily, we have in the soil itself, after clover, a source
from which nitrates are continuously produced; so that it does not much
affect the final yield of wheat, whether heavy