dollars an acre a few days before I started east."

"Well," said Mr. West, "this may have been good land once, but if so
it was before my time. Of course most of our uplands here have been
cropped for upwards of two hundred years; and about all that has
ever been done to keep up the fertility of the soil has been to
rotate the crops. To be sure, the farm manure has always been used
as far as it would go, but the supply is really very small compared
to the need for it."

"Do you think that the proper rotation of crops would maintain the
fertility of the soil?" asked Percy.

"No, I have tried too many rotations to think that, but I suppose it
is a help in that direction, don't you?"

"I would say that crop rotation may help to maintain the supply of
some important constituents of a fertile soil, but it will certainly
hasten the depletion of some other equally essential constituents."

"Well, that's a new idea to me. I may not quite grasp your meaning;
but first tell me about these tests you are making."

When they stopped on the area of poor land as designated by Mr.
West, Percy had turned his auger into the earth and drawn out a
sample of moist soil, which he molded into the form of a ball. He
broke this in two, inserted a piece of blue paper, and pressed it
firmly together. He then laid the ball of soil aside, secured
another sample with the auger, and formed it into a cake with a
hollow in the upper surface. He took from his pocket a slender box