soils injure the color of the nut. Lime is a
necessity and must be supplied if the soil is deficient. Phosphoric acid
and potash are needed.

Greater care than is usually bestowed should be given to the selection
of the peanut seed. In addition to following the principles given in
Section XVIII, all musty, defective seeds must be avoided and all
frosted kernels must be rejected. Before it dries, the peanut seed is
easily injured by frost. The slightest frost on the vines, either before
or after the plants are dug, does much harm to the tender seed.

[Illustration: FIG. 202. A PEANUT PLANT]

In growing peanuts, thorough preparation of the soil is much better than
later cultivation. Destroy the crop of young weeds, but do not disturb
the peanut crop by late cultivation. Harvest before frost, and shock
high to keep the vines from the ground.

The average yield of peanuts in the United States is twenty-two bushels
an acre. In Tennessee the yield is twenty-nine bushels an acre, and in
North Carolina and Virginia it reaches thirty bushels an acre.

SECTION XL. SWEET POTATOES

The roots of sweet potatoes are put on the market in various forms.
Aside from the form in which they are ordinarily sold, some potatoes are
dried and then ground into flour, some are canned, some are used to make
starch, some furnish a kind of sugar called glucose, and some are even
used to make alcohol.

The fact that there are over eighty varieties of potatoes shows the
popularity of the plant. Now it is evident that all of these varieties
cannot be equally desirable. Hence the wise grower will select his
varieties with prudent forethought. He should study his market, his
soil, and his seed (see Section XVIII).

[Illustration: FIG. 203. SWEET POTATOES]

Four months of mild weather, months free from frost and cold winds, are
necessary for the growing of sweet potatoes. In a mild climate almost
any loose, well-drained soil will produce them. A light, sandy loam,
however, gives a cleaner potato and one, therefore, that sells better.

The sweet potato draws potash, nitrogen, and phosphoric acid from the
soil, but in applying these as fertilizers the grower must study and
know his own soil. If he does not he may waste both money and plant food
by the addition of elements already present in sufficient quantity in
the soil. The only way to come to reliable conclusions as to the needs
of the soil is to try two or three different kinds of fertili