Injluence of Climate on Cultivation. 
487 
of March. If the land is also well cultivated and manured, it 
forms a gfood preparation for wheat. In former times flax was 
chiefly grown upon poor land and received no manure, and no 
doubt, under these circumstances, it was a scourging crop. Now, 
however, fine quality of fibre cannot be obtained unless the soil is 
in such high condition that a crop of wheat can be taken after it. 
This, to some extent, is a security that the land will not be de- 
teriorated by the culture of the crop. In those parts of Belgium 
where the finest qualities of fibre are raised, wheat usually follows 
flax. The remains of the liberal manuring which the land re- 
ceives are sufficient to produce a crop of wheat, which is gene- 
rally admitted to require an abundant supply of nitrogen from the 
soil. But what a contrast do the rotations followed in the end 
of the last century in the north of Ireland present ! Young tells 
us that, on good land, the following course of crops was not un- 
common : — 1, potatoes; 2, barley : 3, oats; 4, oats ; 5, flax; 6, 
lay, 2 or 3 years ; 7, oats ; 8, oats. By late sowing, and by being 
satisfied with an inferior product, both as to quality and quantity, 
flax, in the hands of the Irish farmers, was made the agent of 
extracting from the soil the very dregs of fertility. 
The relatively exhausting qualities of different crops have 
formed fertile themes for discussion amonsr agricultural writers. 
Most of the ideas which exist, or existed, among farmers on the 
subject have had some grounds for their prevalence. In many 
cases, however, cause and effect have been confounded. With 
respect to the term " exhaustion," it has not been hitherto suffi- 
ciently recognised that it is often used in tivo senses, which are 
almost diametrically opposite. More accurate ideas on this ques- 
tion will be obtained by considering the effects of temperature, 
in giving plants greater or less power of relying upon the 
atmosphere for a certain supply of food. 
Flax, as has been shown, when sown late in the season, re- 
quires comparatively little manure — that is, carbonic acid and 
ammonia : but, in such circumstances, being capable of appro- 
priating the little that exists in the soil, it is undoubtedly an ex- 
hauster. On the other hand, flax as cultivated around Courtray 
takes a good deal more ammonia from the soil, and, consequently, 
less from the atmosphere. Hence it might be there justly con- 
sidered as peculiarly exhausting, though it is not esteemed so. 
The fact is, it cannot exhaust or take up all the manure which 
is so liberally applied : what remains in the soil is suflBcient 
to raise excellent crops of wheat, which undoubtedly proves 
that the land is far from being left in an exhausted state by the 
flax plant. In ordinary farm management, it will be found that 
any crop which demands a liberal supply of food in the soil 
usually receives as much as leaves a moderate quantity for those 
