riculture, that is, _phosphoric acid_.

_Phosphoric acid_, forming about one half of the ashes of wheat, rye,
corn, buckwheat, and oats; nearly the same proportion of those of
barley, peas, beans and linseed; an important ingredient of the ashes of
potatoes and turnips; one quarter of the ash of milk and a large
proportion of the bones of animals, often exists in the soil in the
proportion of only about one or two pounds in a thousand. The
cultivation of our whole country has been such, as to take away the
phosphoric acid from the soil without returning it, except in very
minute quantities. Every hundred bushels of wheat sold contains (and
removes permanently from the soil) about _sixty pounds_ of phosphoric
acid. Other grains, as well as the root crops and grasses, remove
likewise a large quantity of it. It has been said by a contemporary
writer, that for each cow kept on a pasture through the summer, there is
carried off in veal, butter and cheese, not less than _fifty_ lbs. of
phosphate of lime (bone-earth) on an average. This would be _one
thousand lbs._ for twenty cows; and it shows clearly why old dairy
pastures become so exhausted of this substance, that they will no longer
produce those nutritious grasses, which are favorable to butter and
cheese-making.

[How much phosphate of lime will twenty cows remove from a
pasture during a summer?

What has this removal of phosphate of lime occasioned?

How have the Genesee and Mohawk valleys been affected by this removal of
phosphoric acid?]

That this removal of the most valuable constituent of the soil, has been
the cause of more exhaustion of farms, and more emigration, in search of
fertile districts, than any other single effect of injudicious farming,
is a fact which multiplied instances most clearly prove.

It is stated that the Genesee and Mohawk valleys, which once produced an
average of _thirty-five_ or _forty bushels_ of wheat, per acre, have
since been reduced in their average production to _twelve and a half_
bushels. Hundreds of similar cases might be stated; and in a large
majority of these, could the cause of the impoverishment be ascertained,
it would be found to be the removal of the phosphoric acid from the
soil.

[How may this devastation be arrested?

Is any soil inexhaustible?

What is usually the best source from which to obtain phosphoric acid?]

The evident tendency of cultivation being to continue this murderous
system, and to prey u