underneath the dry bedding, and the acid phosphate sometimes injures
the horses' feet; so that, as a rule, it is better to clean the
horse stables every day and supply phosphorus in raw phosphate at
one-fourth of its cost in acid phosphate."

"Before we leave the nitrogen question," said Mr. Thornton, "I want
to ask if you can suggest how we can get enough of the several
million dollars' worth we have in the air to supply the needs of our
crops and build up our land?"

"Grow more legumes, and plow more under, either directly or in
manure."

"That sounds easy, but can you suggest some practical system?"

"I think so. I know too little of your conditions to think I could
suggest the best system for you to adopt; but I can surely suggest
one that will supply nitrogen for such crop yields as we have
considered: Suppose we change the order of the crops and grow wheat,
corn, oats, and cowpeas, and grow clover with the wheat and oats,
plowing the clover under in the spring as green manure for corn and
cowpeas. If necessary to prevent the clover or weeds from producing
seed, the field may be clipped with the mower in the late summer
when the clover has made some growth after the wheat and oats have
been removed. Leave this season's growth lying on the land. As an
average it should amount to more than half a ton of hay per acre.
The next spring the clover is allowed to grow for several weeks. It
should be plowed under for corn on one field early in May and two or
three weeks later the other field is plowed for cowpeas. The spring
growth should average nearly a ton of clover hay per acre. In this