Secrion IIL.; 1912. [113] Trans. R. S. C. 
Further Experimental Work Towards the Nitrogen-Enrichment of Soils. 
By Frank T. Suurt, M.A., F.1.C., Dominion Chemist, 
and 
A. T. CHARRON, M.A. 
(Read May 15, 1912.) 
The Importance of Soil Nitrogen. 
There is now abundant evidence to show that under ordinary 
cireumstances nitrogen is the most important of all the elements of 
plant food. It is the constituent above all others that determines 
growth and experience would lead us to regard it, in so far as nutrition 
from the soil is concerned, as the dominating and limiting factor in crop 
production. Ina very large measure it is true that a soil’s fertility may 
be measured by its richness in nitrogen. Virgin soils of great produc- 
tiveness, as for instance those covering large areas in the Canadian 
North-West, are almost invariably characterized by a high nitrogen 
content and, on the other hand, soils that are naturally poor and those 
which have become impoverished through irrational systems of farming 
are invariably low in nitrogen. 
The nitrogen of a soil resides in its semi-decomposed organic 
matter (humus) and is slowly made available for crop use through the 
agency of bacterial life, under favourable soil and climatic conditions. 
The important fact in this connection is that humus is the natural store- 
house for reserve nitrogen and that any operation that leads to the 
destruction of the humus causes a dissipation of the nitrogen. The 
reverse is fortunately true, and all additions of humus-forming material 
enrich a soil in nitrogen, though the organic matter furnished by the 
legumes does so to a much greater degree than that from other classes 
of plants. The up-keep and the increase in fertility or productiveness 
is very largely a matter of the up-keep and increase of humus-forming 
material and nitrogen. This being the case the importance to practical 
agriculture of all investigations that have for their object the losses and 
gains in these constituents, under different systems of farming, will be 
obvious. These considerations were brought home to us early in the 
history of the Experimental Farms and trials in the field supplemented 
by chemical work in the laboratory that would furnish data on these 
points were inaugurated in 1893 and have been continued ever since. 
