wledge concerning duration of inoculation
nor the manner in which it is maintained when legumes are not growing,
but we do know that when a legume has once made vigorous growth in a
field, the soil will remain inoculated for a long term of years.

CHAPTER V

THE CLOVERS

Red Clover.--Wherever red clover thrives there is no more valuable
plant than this legume for making and keeping soils productive under
ordinary crop-rotations. The tyro in farming finds his neighbors
conservative in thought and method, and may rightly see room for
improvement. He naturally turns to new crops that are receiving much
exploitation, but should bear in mind that the world nowhere has found
a superior to red clover as a combined fertilizing and forage crop for
use in short rotations. Farmers turn aside from it because it turns
aside from them. There has been increasing clover failure in our older
states for a long term of years. It has become the rule to seed to
timothy with the clover in the short crop-rotations as well as in the
longer ones, and chiefly for the reason that clover seeding has become
no longer dependable. In many regions the proportion of timothy seed
used per acre has been made large because the clover would not surely
grow. In the winter-wheat belt, where the custom has been to make such
seedings with wheat, timothy being sown in the fall and clover the next
spring, this increase in the timothy has made matters worse for the
clover, but it has helped to insure a sod and a hay crop. "Clover
sickness," supposedly resulting from close clover rotations, and the
prevalence of plantain and other weeds, have been assigned as a partial
cause of clover failure. It is only within recent years that the true
cause of much failure has been recognized.

Clover and Acid Soils.--There are limited areas in which some clover
disease has flourished, and in some years insect attacks are serious.
Barring these factors which have relatively small importance when the
entire clover area is taken into account, the causes of clover failure
are under the farmer's control. The need of drainage increases, and the
deficiency in organic matter becomes more marked. The sale of hay and
straw, and especially the loss of liquid manures in stables, have
robbed many farms. These are adverse influences upon clover seedings,
but the most important handicap to clover is soil acidity. There is sad
waste when high-priced clover seed is put into land so