48'8 
Injluence of Climate on Cultivatimi. 
which succeed it. These simple and well-known distinctions 
not having been clearly kept in view, some very erroneous notions 
have long been entertained regarding the relative exhausting 
qualities of the cereals. 
In those districts of Great Britain, for example, where barley 
and oats were usually sown late, wheat was held to be a much 
less exhausting crop than either. The requirements, indeed, 
of wheat and barley stood to each other in almost the same 
relations as those of early and late sown flax. Wheat, as ordi- 
narily cultivated, could not be grown without a liberal allowance 
of manure — so liberal, indeed, that it could not take up all the 
slowly decomposing manure that was applied. Thus it draws 
less upon the natural powers of the soil, since it fails in taking up 
all that was artificially put in. Though, therefore, it derives more 
from the ground than late sown barley, yet, being far more 
prodigal in its requirements, it leaves more waste behind. So, on 
the other hand, late sown barley and flax, being less dependent on 
a supply of nitrogenous matters in the soil, leave it still poorer 
than they found it. Hence we find that wheat is sown after the 
highly-manured and early sown flax around Courtray. On the 
other hand, in moist climates where the late sowing of barley and 
flax is practised, they are often sown after wheat, and become the 
true instruments of exhaustion — as high farming in these circum- 
stances is less essential, or even injurious. 
Whenever the climate does not present obstacles to the late 
sowing of the cereals, a given amount pf grain can be often ob- 
tained with less expenditure of manure than where early sowing 
must be followed. In the early stages of agriculture it has almost 
invariably been found that the cultivators have fallen back upon 
this resource. Tlie principle upon which the practice depends 
has been little recognised in theoretical agriculture. It is one, 
however, which gives us an insight into the nature of the effects of 
special manures, which are greatly dependent on atmospheric in- 
fluences. Phosphates, or superphosphates, for example, when 
applied to late sown cereals, have an influence in promoting their 
growth, which they seldom possess when applied to early sown 
crops. This arises, as already said, in all probability from 
plants having greater facilities for absorbing carbonic acid and 
ammonia from the atmosphere during the warmer season. 
In the ' Genesee Farmer,' of December, 1856, published at 
Rochester, New York State, Mr. Joseph Harris has attempted to 
controvert the doctrine of temperature being, to a certain extent, 
a compensation for ammonia. Nowhere, however, can t])is prin- 
ciple be better illustrated than by the peculiar practices of the 
American farmer. Mr. Lawes' and Dr. Gilbert's experiments 
have led them to the same conclusion with regard to the barley 
