nitrogenous matter will be consumed to produce animal heat and to
sustain the vital functions, and the refuse, or the solid and liquid
droppings of the animals, will be manure.

If the crop rots on the ground, nothing is added to it. If it ferments,
and gives out heat, in a heap, nothing is added to it. If it is passed
through an animal, and produces heat, nothing is added to it.

I have heard people say a farmer could not make manure unless he kept
animals. We might with as much truth say a farmer cannot make ashes
unless he keeps stoves; and it would be just as sensible to take a lot
of stoves into the woods to make ashes, as it is to keep a lot of
animals merely to make manure. You can make the ashes by throwing the
wood into a pile, and burning it; and you can make the manure by
throwing the material out of which the manure is to be made into a pile,
and letting it ferment. On a farm where neither food nor manure of any
kind is purchased, the only way to make manure is to _get it out of the
land_.

"From the land and from the atmosphere," remarked the Doctor. "Plants
get a large portion of the material of which they are composed from the
atmosphere."

"Yes," I replied, "but it is principally carbonaceous matter, which is
of little or no value as manure. A small amount of ammonia and nitric
acid are also brought to the soil by rains and dews, and a
freshly-stirred soil may also sometimes absorb more or less ammonia from
the atmosphere; but while this is true, so far as making manure is
concerned, we must look to the plant-food existing in the soil itself.

"Take such a farm as Mr. Dewey's, that we have already referred to. No
manure or food has been purchased; or at any rate, not one-tenth as much
as has been sold, and yet the farm is more productive to-day than when
it was first cleared of the forest. He has developed the manure from the
stores of latent plant-food previously existing in the soil and this is
the way farmers generally make manure."

CHAPTER XI.

THE VALUE OF MANURE DEPENDS ON THE FOOD--NOT ON THE ANIMAL.

"If," said I, "you should put a ton of cut straw in a heap, wet it, and
let it rot down into manure; and should place in another heap a ton of
cut corn-fodder, and in another heap a ton of cut clover-hay, wet them,
and let them also rot down into manure; and in another heap a ton of
pulped-turnips, and in another heap a ton of corn-meal, and in another
heap a ton of bran, and in a