CHAPTER VI 
GREEN MANURES AND COVER CROPS 
gi. As a source of humus. — It has been previously in- 
dicated (76) that humus in large amounts is essential to 
success in every line of vegetable gardening and that 
stable manure supplies it in the best form. While this is 
true, it is impossible for thousands of commercial grow- 
ers to secure enough stable manure to maintain the pro- 
ductiveness of their soils. This is particularly true of 
truckers living remote from great centers of population. 
It is easy enough for gardeners operating a few miles 
from the city to secure sufficient manure to produce good 
crops, but it is quite a different proposition for the 
grower living hundreds of miles from available supplies. 
It is impracticable for extensive truckers to use very 
freely manure which costs as much as $5 a ton spread on 
the land. In many trucking sections it is not only much 
more economical to maintain the necessary amount of 
Vegetable matter in the soil by the use of green crops, 
but it is also an effective means of keeping the soil in the 
proper sanitary condition. 
92. Extent used. — The growing of green crops and 
catch crops for manurial purposes has become a general 
practice in many trucking sections. Marked progress 
in the use of green manures has been made in New Jer- 
sey, where, for example, at Freehold, potatoes have been 
grown annually upon the same land for many successive 
years by sowing crimson clover, rye or wheat after har- 
vesting each crop of potatoes. It often happens that the 
continued use of crimson clover year after year results 
in an accumulation of too much nitrogen for the best re- 
sults with potatoes and it is necessary to substitute rye 
