the air being greater in the case of badly depleted soils.

A big factor of error is found in the valuations of the ingredients
found in the crop. All plant-food is worth to the farmer only what he
can get out of it. He may be able to use 50 pounds of nitrogen per acre
in the form of nitrate of soda, at 18 cents a pound, when growing a
certain crop, but could not afford to buy, at market price of organic
nitrogen, all the nitrogen found in the clover crop, and therefore it
does not have that value to him.

On the other hand, these estimates do not embrace the great benefit to
the physical condition of the soil that results from the incorporation
of a large amount of vegetable matter.

Discussion has been given to this phase of the question in the interest
of accuracy. Values are only relative. The practical farmer can
determine the estimate he should put upon clover only by noting its
effect upon yields in the crop-rotation upon his own farm. It is our
best means of getting nitrogen from the air, it provides a large amount
of organic matter, it feeds in subsoil as well as in top soil, bringing
up fertility and filling all the soil with roots that affect physical
condition favorably, and it provides a feed for livestock that gives a
rich manure.

[Illustration: Red clover on the farm of P. S. Lewis and Sons, Point
Pleasant, W. Va.]

Taking the Crops off the Land.--The feeding value of clover hay is so
great that the livestock farmer cannot afford to leave a crop of clover
on the ground as a fertilizer. The second crop of red clover produces
the seed, and, if the yield is good, is very profitable at the prices
for seed prevailing within recent years. The amount of plant-food taken
off in the hay and seed crops would have relatively small importance if
manure and haulm were returned without unnecessary waste. Van Slyke
states that about one third of the entire plant-food value is contained
in the roots, while 35 to 40 per cent of the nitrogen is found in the
roots and stubble. Hall instances one experiment at Rothamstead in
which the removal of 151 pounds of nitrogen in the clover hay in one
year left the soil enough richer than land by its side to produce 50
per cent more grain the next year. He cites another experiment in which
the removal of three tons of clover hay left the soil so well supplied
with nitrogen that its crop of Swede turnips two years later was over
one third better than that of land which had not