08 RECLAIMING LOST NITROGEN 
soil, or elsewhere, by means of decomposition it finally allows the 
nitrogen to pass off as a free gas to join nature’s inexhaustible 
supply 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 
POCO CBC. 
LIECOM POSURE 
BACCTHW 
“A 
B Ame he freeNittogen 
Soil Laccentte 
MAb 
Nitrates (Insoil) 
Fic. 19.—The nitrogen cycle. 
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 com- 
mercial 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. 
