THE LOSS OF NITROGEN. 9 1 
in the air. It is quite necessary for the continuance of soil fertility 
that this lost material should be restored. 
Our farm lands slowly become incapable of supporting the 
crops demanded of them. This loss of fertility in worn-out farms 
is due, doubtless, to a number of factors, but the loss of nitrogen 
is certainly the most prominent one. All over the agricultural 
world it has been found necessary to replace this lost nitrogen in 
the soil. For this purpose we have depended mostly upon commer- 
cial fertilizers, which commonly contain nitrogen in the form of 
nitrates. Of such fertilizers there is a small supply in the 
world, chiefly in South America, and as they are brought from 
long distances they are sold at high prices. But the few large 
deposits of nitrates in the world are being rapidly exhausted. 
The high prices of nitrates are necessary and are bound to increase 
as the soil needs them more and more and as the supply diminishes. 
Clearly enough, the supplying of the lost nitrogen will become 
more and more expensive as the great nitrogen stores are used up. 
The seriousness of this problem of a constant draining of nitrogen 
from the soil has been quite prominent in the minds of chemists 
and agriculturists, as they have learned in the last few years the 
significance of nitrogen for agriculture. 
The continuation of agriculture depends upon the existence 
of some means of reclaiming the nitrogen from the atmosphere 
for the use of plants. If there is no such means it is evident that 
the nitrogen store of the soil will be used up and vegetation will 
eventually, and, in highly cultivated lands, speedily die of nitrogen 
starvation. If, on the other hand, there is a possibility of reclaiming 
such lost nitrogen there is no need of nitrogen starvation, since there 
is an absolutely unlimited store of this element in the form of the free 
nitrogen of the air. It is quite evident that there is some means 
within the reach of organic nature for making use of this atmos- 
pheric nitrogen. Vegetation has continued on the earth for an 
unknown number of centuries without any apparent diminution of 
the nitrogen supply. This would not have been possible unless 
the soil could have obtained from the air a stock of nitrogen to 
replace that lost by the processes already indicated. 
