172 
Lrfluence of Climate on Cultivation. 
increases the productiveness of the crop. A century ago barley 
was rarely sown before the month of May, as the sources of 
manure were then exceedingly scanty. This is still more forcibly 
brought out in former times in the cultivation of here or bigg, 
the four-rowed barley. This variety Avas usually sown in the 
beginning of June, and was still less dependent on a supply of 
nitrogenous manure. Indeed, it was thought to exhaust tlie soil 
comparatively little, as it could be raised on ordinary land for 
many years in succession with the slightest dressings of manure. 
These facts show that barley may be sown late in the season 
with advantage in the cooler and moister parts of Britain. In 
such circumstances it can be grown with less manure, which to 
a certain extent acts as a compensation for the inferior quantity 
and quality of the produce. One of the most direct effects of 
this, however, is in retarding the general introduction of im- 
proved systems of farming, in which green crops occupy more 
attention. On the poor soils of Norfolk neither barley nor wheat 
can be got without turnips, whereas in moist climates very 
different practices may be followed with a greater measure of 
success ; and the necessity for turnip culture not being so im- 
perative, the crop is only slowly introduced even in those districts 
where the climate is best suited for its growth. 
The effects of the physical or mechanical properties of soil on 
the growth of barley in relation to climate is in some respects 
different from tliat of wheat ; these differences, however, have not 
a little to do with the seasons at which the barley crop admits of 
being sown. The stiff clay soils of Suffolk and Huntingdon we 
usually recognise as well fitted for the growth of wheat ; but, 
through the improved mctliods of cultivating these soils, they 
have become admirablv adapted for the growth of barley. Tlie 
rotation adopted—of clover, wheat, fallow, barley — permits of the 
soil being reduced to a fine tilth by the winter frosts. Tlie finely 
pulverized mould sustains the growth of the barley crop as well 
as the finest turnip loams. Under these circumstances, the 
vegetable manuring of the clover crop acts more beneficially on 
the wheat which follows it than it would on the barley ; indeed, 
this crop is much sooner injured by an excess of vegetable matter 
in the soil than wheat : the latter is cultivated with success 
in the humus soils of the Lincolnshire fens, where barley does 
not thrive. In moist and humid clim.ates barley is very suscep- 
tible of vegetable matter, and where it abounds becomes gross in 
its habits. Its use is most advantageous on the lightest soils, as 
is also the case with wheat, rendering them better fitted for sus- 
taining growth in dry weather. 
As the climate increases in aridity, so must the soil improve 
in its physical properties, to maintain the healthy growth of the 
