8 BULLETIN 6, U. S. DEPARTMENT OF AGRICULTURE. 
BLACKBERRY, RASPBERRY, AND BLACKCAP. 
The blackberry, the American red raspberry, and the blackcap are 
found wild in acid soils and all thrive in cultivation in such land if 
the ground is well supphed with humus. 
POTATO. 
The potato has long been recognized as yielding especially well 
when grown on a newly turned sed or on newly cleared land, condi- 
tions which are now recognized as productive of acidity as well asa 
later increase of humus. The potato, moreover, furnishes one phe- 
nomenon of special interest to acid-land agriculture. The potato 
scab, a disease which reduces the size of the tubers, injures their ap- 
pearance, and lessens their value, is controlled without difficulty if 
the soil reaction is acid. The disease is caused by a fungus known 
as Oospora scabies, the growth of which is inhibited by acidity. 
SWEET POTATO. 
The sweet potato, the cultivation of which extends as far north as 
New Jersey, yields heavily in acid soils. In the South it is the 
standard vegetable on such lands. 
RYE. 
Rye is a cereal that grows almost as well on acid as on nonacid 
soils. It is the characteristic grain on the reclaimed acid heather 
lands of northern Europe. In the United States it is found par- 
ticularly useful as a cover crop on areas subject to washing in winter, 
whether the rye is later cut for hay, or plowed under for green 
manure. or harvested for its grain. | 
oats. 
Asa grain for spring sowing, oats do well in acid soils, though this 
crop is not so acid tolerant as millet. It is often useful in rotations 
where the crop of the preceding summer can not be harvested early 
enough to permit the successful sowing of a winter cover crop like rye. 
MILLET. 
The different varieties of foxtail millet, including common millet, 
German millet, and Hungarian millet, are strongly acid tolerant. | 
As they are also drought resistant and reach maturity in a remark- 
ably short perrod, they are useful for summer sowing in land tem- 
porarily vacant between the more important crops of a rotation. 
BUCKWHEAT. 
Buckwheat is well known asa pioneer crop on newly cleared timber- 
land. Its reputation also as a crop for worn-out lands is another 
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