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Resource Constraints on Food Supply
There are only two ways to expand agricultural
production: Increase the area
planted (which, where climate permits,
might include producing more than
one crop on the same land each year),
or increase the production per unit of
land. Worldwide, farmers could double
the number of hectares (one hectare
is 2.47 acres) of land in production;
however, there is only about 10 percent
more potentially arable land that is not
forested, highly erodible or subject to
desertification. Expansion beyond this
land would involve massive destruction
of forests and, with them, wildlife
habitat, biodiversity and carbon sequestration
capacity, all while accelerating
global warming.
Most of the potentially arable land
is inferior to that already in production
and is located in remote areas of
Sub-Saharan Africa and South America,
which have minimal infrastructure. To
sustainably double agricultural production
will require most of the increase to
come from greater production per unit
of land already in cultivation.
Availability of freshwater for agriculture
may become an even larger
constraint to doubling production than
land availability. Farmers account for
about 70 percent of the freshwater used
in the world. With more than half of the
world’s population living in cities now,
a number projected to rise to 70 percent
by 2050, the world’s farmers will no
longer have access to 70 percent of the
freshwater. Cities will outbid farmers
for available water. Whereas farmers
may have to double the average productivity
of land already in agricultural
production, they may have to triple the
“crop per drop,” the output per unit of
freshwater they use.
Food Productivity and Security
There are great differences among
regions of the world in crop yields,
which reflect differences in genetic
potential embodied in the seeds
planted, availability of water from precipitation
or irrigation, adequacy of the
nutrition available to the plants from
the soil or fertilizer, and effectiveness
of the control of weeds, insects, birds
and diseases that reduce productivity
Year of
Agriculture
atSAIS
relative to potential. The regional disparities
in crop yields suggest it should
be possible to significantly increase
productivity per unit of land. With their
low yields, many low-income countries’
farm sectors contribute significantly
less to their national food supply and
global food security than they could.
A century ago, cereal grain yields in
Western Europe and the United States
were not much higher than the low
levels found in Sub-Saharan Africa
today. The sizable gains in productivity
since then have reduced the unit cost
of production and have kept the price
of food lower to the great benefit of
poor consumers, who spend the largest
fraction of their incomes on food. This
has lessened the incidence of famine in
the world and has allowed millions of
hectares of trees to remain standing in
the forests instead of being cut to make
way for cultivation.
Reducing Farm Household Poverty
The majority of the world’s agricultural
production takes place on family farms,
where household members perform
most of the labor. In addition to providing
part of the family’s annual food
supply, farming gives the household
cash income—receipts from selling its
products minus what it pays for production
inputs (such as seed, fertilizer,
pesticides and fuel) and hired labor.
Most farm households earn significantly
less than households whose
income derives from other economic
activities. In fact, 70 percent of the
extreme poverty and associated hunger
in the world is in rural areas, and most
of the rural poor derive their meager
incomes from farming.
There are only five ways to lift lowincome
farm households out of their
poverty (other than from social welfare
support, which rarely exists in rural
areas of poor countries): Increase the
productivity per hectare of land used
in producing the crops being grown;
change the mix of what is produced to
crops with higher value per hectare; get
access to more land (through purchase,
rental or land reform) or other incomegenerating
assets; opt for one or more
members of the farm household to
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