CHAPTER II.-THE PRODUCTION OF CROPS.
1. The average yield per acre.— Various factors may individually
or collectively account for changes in the average yield per acre
of the different crops from one year to another. The most
Important is undoubtedly the weather from the time the land is
being prepared for sowing to the completion of the harvest,
but over extended periods there may also be changes in the
standard of cultivation, in the class of seed used, and in the
average fertility of the land on which the crop is grown. Account
must also be taken of the fact that good and bad years from the
Point of view of weather are unevenly distributed, so that any
one short period (e.g., ten years) may contain more favourable
or unfavourable years than another. It would, however, be of
considerable interest if any definite improvement in output
could be shown to have occurred, apart from the fortuitous
Influence of favourable and unfavourable seasons. To test the
question to some extent diagrams have been prepared, showing
for each of the three principal cereals the average yield per acre
1 England and Wales from 1885 to 1925 (the forty years for
which figures of yield are available) together with ten-year
averages, and also ten-year averages of the area under each crop
(see Diagrams I and II).
The ten-year average yield per acre of wheat showed fairly
steady progress for the first 20 years, and it is perhaps significant
that during the greater part of this time the wheat acreage was
declining rapidly. Presumably the land on which the crop
continued to be grown would be the land which could be most
profitably maintained under wheat, and would in médny cases
be the land which gave the best yield. This may account to
Some extent for the increasing yield per acre but it has to be
remembered that much of the land which has gone out of cultiva-
tion under wheat is heavy land which gives a good yield but is
very expensive to work. It seems probable that the weather
Was on the whole more favourable for agricultural production
during these years. Subsequently, there was a marked decline
followed by an upward turn. . .
In the case of barley, the diagram indicates a fluctuating
Movement in the first 20-30 years without any well-marked
tendency, followed by a definite decline. In this case there hag
been a reduction in area throughout. The ten-year average yield
Per acre of oats rose between 1885-94 and 1902-11, but as in
the cage of the other two corn crops this was followed by a
decline, At the same time the acreage increased. On the whole,
there is some general resemblance in these curves, and the fall
I the average yield in all three cases towards the close of the
Period suggests that there is a common cause, which is presumably
a greater proportion of unfavourable seasons,