148 ALFALFA FARMING IN AMERICA. 
is said that manure enough has been applied since 
it has been in possession of the United States to 
cover the soil with a layer several feet deep, and 
yet the land is of only very moderate fertility. Why? 
Because it is so lacking in carbonate of lime. 
Coming back to my father’s idea that land could 
be given such an impetus towards fertility and pro- 
ductiveness that it would ‘‘keep a-going”’ it should 
be said that it is only a partial truth, after all. 
Doubtless the nitrogen content of the soil can be 
maintained. In order to do this leguminous crops 
should come with somewhat frequent recurrence, 
since legumes restore nitrogen faster than anything 
else we know. And alfalfa is the most vigorous ni- 
trogen gatherer at our command. No one can store 
a soil with fertility and draw upon it with maize 
or oats or wheat or timothy grass without rapidly 
depleting his store. All these things are soil rob- 
bers; they do not create or secrete fertility for the 
soil. 
Phosphorus Needed.—Nor can legumes or alfalfa 
do impossibilities. The mineral elements are pres- 
ent in fixed amounts. Of potash one may have a 
great abundance and on many soils need never 
worry nor concern himself, but phosphorus is usual- 
ly a thing needed and not in sufficient supply. It must 
be remembered that plants cannot build their tissues, 
form their blooms and mature their seeds without 
using in regular ‘‘balanced ration’’ all the elements 
of plant food. They cannot make use of an excess 
of nitrogen profitably when phosphorus is in scant 
