the clover seeded in the wheat.

Potatoes after Corn.--When potatoes are grown in the corn belt, a five
years' rotation of corn, potatoes, oats, wheat, and clover, or corn,
potatoes, wheat, clover, and timothy, is one of the best. When a late
potato crop is grown, there is not time for seeding to wheat in cool
latitudes, and the oat crop, or the soybean, fits in best. Farther
south, where the oat crop is less profitable, there usually is time to
go directly to wheat.

The advantage in this rotation is that the fresh manure can be used on
the sod for the corn, and the potato thrives in the rotted remains of
the sod and manure. Corn leaves the soil in good physical condition for
the potato. Commercial fertilizer is used freely for the potato, which
repays fertilization in higher degree than most other staple crops. The
land can be prepared for seeding to wheat and grass with a minimum
amount of labor. The rotation is excellent where there is enough
fertility for the potato, which usually can be by far the most
profitable crop in the entire rotation.

A Three Years' Rotation.--Farm conditions may require that certain
fields in the farm go under a crop-rotation covering three years. In
the winter wheat belt this may be clover, corn, and wheat, or clover,
potatoes, and wheat. It is an excellent rotation when early planted
potatoes or silage corn follows the sod, favoring the wheat in which
the clover again is seeded. The ground is plowed only once in three
years. The clover furnishes hay for the farm, and organic matter with
nitrogen for the land. There are two cash crops in the rotation when
potatoes are grown, and that makes a heavy draft upon fertility.
Experience has demonstrated that commercial fertilizers or manure
become necessary as a supplement to clover in a three years' rotation
embracing potatoes. This rotation gives good control of most weeds and
insect enemies.

Where wheat is unprofitable, the oat crop is used in its stead. If
mixed hay is wanted, timothy is sown with the clover. This is poor
practice from the standpoint of soil fertility because the draft upon
humus is heavy in a close rotation embracing a tilled crop and small
grain. The sod should be chiefly clover, or manure should be used in
connection with commercial fertilizer.

Grain and Clover.--In the case of some soils it is possible to grow a
wheat or corn crop each year, clover being grown as a catch crop. In
the long run, this practice will