500 
Report of Experiments on the Growth of Wheat. 
long; ago expressed our conviction that if the supplies of ammonia 
were much increased, the available mineral constituents of our 
soils would in their turn become relatively deficient. 
It is one thing to maintain, as we do, that under the existing 
conditions of agriculture in this country, the nitrogen in manures 
has justly" a preponderating value attributed to it, and quite 
another to advocate as we do not, and never have done, that 
nitrogenous manures alone should be obtained from without. 
Nor is it the practice of intelligent farmers so to make use of the 
nitrogenous manures in the market. Those which the most 
nearly approach the character of purely nitrogenous manures, 
such as ammonia-salts and nitrate of soda, are rarely even for a 
single crop used alone, and never so by any farmer of moderate 
intelligence, unless — to say nothing of the periodical supplies of 
the home manures, perhaps enriched by the consumption on the 
farm of purchased food for stock — he applies specially phosphatic 
manure to some other crop in his course. 
The objection that has been raised against the practice of 
purchasing food for stock, that that which is a gain of constituents 
to the purchaser is in the same degree a loss to the seller, surely in 
these days of growing intelligence, and of extension of commercial 
freedom and interchange of commodities throughout the world, 
hardly requires serious consideration. The producers in thickly- 
populated districts will reap the just reward of their folly if they 
dispose, without due compensation, of products which the require- 
ments of their own markets, or of their own soils, render it de- 
sirable that they should keep at home. But, if countries thinly 
populated in relation to the area, and to the capabilities of the 
soils and climates with which they have to deal, should not supply 
the wants of those more densely peopled, in exchange for such 
commodities as they may need and their customers may be 
able to supply, because in so doing they would dispose of a portion 
of the mineral constituents annually liberated within their soils, 
the sooner this chemical principle of protection is understood and 
acted upon, and the sooner the commercial system of the world is 
abandoned, and we make up our minds to be satisfied with that 
which is produced at our own doors, the better we suppose will 
it be. For our own part, we are disposed to entertain some trust 
and confidence that the laws of supply and demand, if left un- 
fettered by artificial restrictions, will in this, as in other matters, 
so regulate production as may best contribute to the wants of 
mankind at large. 
Taking, however, the conditions of our agriculture as they 
really exist, and not anticipating a revolution in the sense just 
supposed, we are disposed to consider that the relation of the 
supplies of potass and other mineral constituents, to those of 
