58 
GARDENS AND THEIR MEANING 
A recent writer gives such a person no quarter. He says : 
" The individual who deliberately fails to return to the soil its 
fair share of the product abuses nature, cheats and degrades 
himself, robs his children, defrauds the future, and is not an 
intelligent, patriotic citizen.” 
It is a blessing that new and more economical means of 
fertilizing have supplanted the old. The three most valuable 
chemical elements supplied by fertilizers are potash, phos- 
phoric acid, and nitrogen. Nitrogen, the most important ele- 
ment in manure, happens to be the most costly of the three. 
Until recently it was believed that green plants could 
under no circumstances feed on free nitrogen, but that they 
must use it in some one of its chemical combinations. This 
is doubtless true of most green plants. It has, however, been 
found that one class of plants is able to collect free nitro- 
gen from the air mixed in with the soil, and stores this in 
its roots. 
These legumes, or pod-bearing plants, including the clover, 
vetch, and pea, as well as alfalfa and soy bean, bear little 
nodules, like warts, upon their roots. The nodules are made 
up of a lot of microscopic plants, or bacteria, ten thousand 
or so to the square inch. The free nitrogen in the air supplies 
these bacteria with food. Besides using the free nitrogen as 
food, these bacteria store it, or ” fix ” it, as the term is, so that 
later the whole plant may get the benefit of it. Moreover, 
through the plowing under of nitrogen-fixing plants the earth 
becomes enriched by just so much new nitrogen. To-day 
these tiny organisms alone are saving farmers millions of dol- 
lars in fertilizers. In some cases, however, it happens that 
these leguminous plants do not develop nodules. But if 
nodules are lacking, they can be supplied, so scientists have 
learned, by inoculation. The formula for inoculation is simple, 
so that the process has frequently been carried on even by 
