weeding, fertilizer, drainage and so on, which
was also subject to diminishing returns to
labour and capital. Ricardo, like Malthus
(1803), assumed that population growth in-
creases would be arrested by a decline in real
wages, by increases in rents and by per capita
food decline.
There is a third form of intensification that
rests upon the deployment of the increasing
labour force to crop farmland more frequently
(i.e. to increase the cropping intensity or to
reduce the fallow). Thereduction of the period
of fallow(the period of non-cultivation or re-
covery in which the land is allowed to regen-
erate its fertility and soil capacities) was
a major way in which European agriculture
increased its output during periods of popula-
tion growth, as observed at the time when
Ricardo and Malthus were writing. Fallowing
does not imply poorer or more distant land,
but as the fallow length is reduced greater
capital and labour inputs are required to pre-
vent the gradual decline of crop yields and the
loss of fodder for animals.
Esther Boserup (1965, 1981) made fallow
reduction a central plank of her important
work on agrarian intensification. While fallow
reduction is also likely to yield diminishing
returns, these are more than compensated for
by the additions to total output conferred by
increased cropping frequency.
In the eighth century the two-field system
predominated in Western Europe, but by the
twelfth and thirteenth centuries the three-field
system had come to displace its two-field
counterpart in high-density regions (seefield
system). By the eighteenth and nineteenth
centuries, the fallow had begun to disappear
entirely. Boserup (1965) saw this fallowing
reduction as the central theme in agrarian his-
tory and the centrepiece around which the
Malthusian debates over overpopulation and
famine ultimately turned (cf. malthusian
model). In her view, output per person–hour
is highest in the long-fallow systems – for ex-
ample, the shifting or swiddening systems of
the humid tropical forest zone, in which di-
verse polycropping of plots for one or two
seasons is then followed by a fallow of 15–25
years (depending on local ecological circum-
stances: cf. shifting cultivation) – and
population growth is the stimulus both for
reduction in fallow and the innovations asso-
ciated with intensified land use.
Boserup envisaged a progressive series of fal-
low reductions driven by the pressure of popu-
lation (and the threat of exceeding the
carrying capacity). Long-fallow systems
that are technologically simple (associated
only with the digging stick and the axe) are
displaced by bush fallow (6–10 year fallow)
and short fallowing (2–3 year fallow) in which
the plough is a prerequisite. Annual, and finally
multiple, cropping appear as responses to con-
tinued population pressure. Across this pro-
gression of intensification is a reduction in
output per person–hour, but a vast increase in
total output. The shift to annual and multiple
cropping also requires substantially new forms
of skill and investment, however, which typic-
ally demandstate-organized forms of invest-
ment and surplus mobilization. Boserup saw
much of Africa and Latin America as occupy-
ing an early position in a linear model of in-
tensification in which output could be
expanded by fallow reduction. The ‘Boserup
thesis’ refers to the relationship between popu-
lation growth and agrarian intensification,
measured through fallow reduction and a de-
creasing output per person–hour.
Implicit in the Boserup thesis, although
she did not develop these implications, is the
changing role ofland tenure, the increasing
capitalization of the land and more complex
forms of state–society interaction. Indeed,
Boserup’s work has been taken up by a num-
ber of archaeologists and anthropologists, who
have charted patterns of state formation
and social development in terms of agrarian
intensification.
Boserup’s anti-Malthusian theory lays itself
open to all manner of charges, including a
non-linear form of techno-demographic deter-
minism and a general lack of attention to the
ecologicallimits of intensification (Grigg,
1980; cf.teleology). It is not at all clear
how or whether Boserup’s thesis can be ap-
plied tomarketeconomies. Indeed, her thesis
does not seem to be much help, for example,
in the English case: in its essentials, the agri-
cultural technology of the eighteenth century
(the Norfolk four-course rotation) had been
available since the Middle Ages, and although
the eighteenth century was a period of popu-
lation growth, the previous period of sustained
demographic growth from the mid-sixteenth
century had witnessed no intensification as
such (Overton, 1996: seeagricultural revo-
lution). Processes of intensification are nat-
urally on the historical record and the
reduction of fallowing in thethird world–
whether driven by demographic growth or
not – has been and continues to be documen-
ted (see Guyer, 1997). But intensification is
a socially, culturally and politically complex
process. To the extent that fallow reductionGregory / The Dictionary of Human Geography 9781405132879_4_B Final Proof page 54 31.3.2009 11:01amBOSERUP THESIS