system was probably introduced after clearance of additional land from forest and waste
to make a third field. Even where it was introduced without an associated expansion of
arable land, such a three-course rotation effectively increased the total arable land under
cultivation in any year. Unless other improvements in agricultural practice were also
introduced, the new rotation methods would not have improved production for long, for
yields should have dropped on fields expected to produce in two out of three instead of
one out of two years. Instead, in this period, not only did older fields produce slightly
more often, but yield/seed ratios actually appear to have increased to about 4 to 1 by the
14th century. These higher yields are significant, since they produced a doubling of net
yields or consumable produce from earlier gross yields of 2.5 to 1. Yields were
maintained partly due to more frequent plowing of the fallow lands and the introduction
of spring crops, such as oats and pulses, which had nitrogen-fixing capability. More
important were better iron tools, which allowed clearance of new lands, and the
introduction of the heavy, wheeled plow, or charrue. In addition to wheels, this plow had
an iron cutting knife, or coulter, which went ahead of the share to cut open the soil, an
iron share, and an iron or wooden moldboard, which turned over the sod completely in
one direction or the other. This meant that it dug deeper into the soil to turn over the sod
sufficiently to increase the fertility of existing tillage, and it could be used for tilling the
heavier soils of river valleys previously inaccessible to agriculture. The disadvantage of
the new plow was that it required eight oxen or a pair of horses to pull it, an expense that
often must have been shared among villagers. It was also considerably harder to turn this
plow. The shape of holdings in fields needed to be changed to the long, slightly S-shaped
strips familiar from aerial photographs; except where it was introduced in entirely noval
lands, this must have meant a considerable redistribution of village lands when the new
plow was adopted. The new wheeled plow was frequently pulled by horses, an innovation
that was possible only after the introduction of the horse collar, better hitching methods,
and iron horseshoes. The use of horses thus, like the plow itself, required increased
availability of iron and is linked to increased iron production and the burgeoning of
forges throughout the countryside during this period. The horses used to pull these plows,
like the mounts of the warriors who owned the estates, were fed oats, a spring crop, so
that the introduction of horse power in the fields also probably encouraged the spread of
the new three-course rotation.
These interrelated innovations in agricultural practice and technology appeared in
France between the years 950 and 1150, particularly in the region north of the Loire, and
would be distributed fairly widely in north and central France (although much less so in
the Midi, where soil and climate were not appropriate) by the 12th and 13th centuries.
They marked what has rightfully been called the “Agricultural Revolution of the Middle
Ages.” This revolution was accompanied by considerable demographic growth, by a
widespread expansion of the total area under cultivation in France, by the building of
castles by territorial lords, by increased agricultural yields, and by a revival of towns and
specialized artisanship in those towns. Much of this revolution, which took place in the
10th and 11th centuries, is undocumented, for there is a dearth of records for the period
during and after the 9th-century invasions. Until recently, historians gave credit for the
agricultural revolution to monks, particularly the new monks of the 12th century. More
recent studies instead show that anonymous peasants needing more land for their
families, hermits going out to live alone in the forest, and lords intent on getting a share
Medieval france: an encyclopedia 22