Geography Reference
In-Depth Information
the use of land. He reasoned that the greater the distance
to market, the higher the transport costs that had to be
added to the cost of producing a crop or commodity.
The
Von Thünen model
(including the ring of for-
est) is often described as the fi rst effort to analyze the spa-
tial character of economic activity. The Thünian patterns
discerned in many parts of the world are not solely the
result of the forces modeled by von Thünen. Differences
in climate type and soil quality weigh heavily on the kinds
of goods produced in a place. Yet if you drive east out of
Denver, heading for Nebraska, you cannot miss a certain
concentric zonation that puts dairying and market gar-
dening nearest the city, cash grains such as corn (plus soy-
beans) in the next “ring,” more extensive grain farming
and livestock raising beyond, and cattle ranching in the
outermost zone.
Geographer Lee Liu studied the spatial pattern of
agricultural production in one province of China, giving
careful consideration to the intensity of the production
methods and the amount of land degradation. Liu found
that the farmers living in a village would farm lands close
to the village as well as lands far away from the village with
high levels of intensity. However, the methods used varied
spatially, resulting in land improvements close to the vil-
lage and land degradation farther from the village. In
lands close to the village, farmers improved lands through
“decades of intensive care,” in particular putting organic
material onto the fi elds, which made the grasslands close
to the village “fertile and productive.” In lands more
remote from the village, farmers tended to use more
“chemical fertilizer, pesticides, and herbicides” and fewer
conservation tactics, resulting in land degradation,
whereby “the originally fertile remote land became
degraded.” Liu argued that this pattern in modern China
occurs in large part because farmers live in the village, not
in the remote fi elds, and therefore put most of their time
and energy into the fi elds closest to them.
Even when agricultural production does not conform
to the concentric rings of von Thünen's model, his under-
lying concern with the interplay of land use and transpor-
tation costs frequently still explains agricultural patterns.
The fresh fl owers grown in the Caribbean for sale in New
York City could be viewed as the application of the von
Thünen model on a larger scale, for it is less expensive to
grow fl owers in the Caribbean and ship them to New York
City than it is to grow them in other locations.
philanthropists funded research on maize (corn) produc-
tion in Mexico, trying to fi nd a hybrid seed that would
grow better. They did, and by 1960 Mexico was no longer
importing corn because production within the country
was high enough to meet demand. In the 1960s, the focal
point of the Green Revolution shifted to India, when sci-
entists at a research institution in the Philippines crossed a
dwarf Chinese variety of rice with an Indonesian variety
and produced IR8. This new rice plant had a number of
desirable properties: it developed a bigger head of grain,
and it had a stronger stem that did not collapse under the
added weight of the bigger head. IR8 produced much bet-
ter yields than either of its parents, but the researchers
were not satisfi ed. In 1982 they produced IR36, bred from
13 parents to achieve genetic resistance against 15 pests
and a growing cycle of 110 days under warm conditions,
thus making possible three crops per year in some places.
By 1992, IR36 was the most widely grown crop on Earth,
and in September 1994, scientists developed a strain of
rice that was even more productive than IR36. In addition
to improving the production of rice, the Green Revolution
brought new high-yield varieties of wheat and corn from
the United States to other parts of the world, particularly
South and Southeast Asia.
Coming at a time of growing concern about global
hunger, the increased yields of the Green Revolution were
truly extraordinary. In subsequent decades, most famines
resulted from political instability rather than failure in
production. India became self-suffi cient in grain produc-
tion by the 1980s, and Asia as a whole saw a two-thirds
increase in rice production between 1970 and 1995. These
drastic increases in production stemmed not only from
new seed varieties but also from the use of fertilizers, pes-
ticides, irrigation in some places, and signifi cant capital
improvements.
The geographical impact of the Green Revolution
is highly variable, however. Its traditional focus on rice,
wheat, and corn means that it has had only limited
impact throughout much of Africa, where agriculture is
based on different crops and where lower soil fertility
makes agriculture less attractive to foreign investment.
But innovations are continually being developed.
Researchers at the International Rice Research Institute,
for example, are working to breed a genetically modifi ed
“super rice” that will not have to be transplanted as seed-
lings but can be seeded directly in the paddy soil. It may
yield nearly twice as much rice per acre than the average
for strains in current use. The charting of the genome of
rice (the 12 chromosomes that carry all of the plant's
characteristics) may make it possible to transform rice
genetically so that it will continuously acquire more
desirable properties. Not only could yields improve; so
could resistance to diseases and pests.
Increasingly, researchers are turning their attention
to new agricultural products, and this could expand the
The Third Agricultural Revolution
The
Third Agricultural Revolution
, also called the
Green Revolution
, dates as far back as the 1930s, when
agricultural scientists in the American Midwest began
experimenting with technologically manipulated seed
varieties to increase crop yields. In the 1940s, American
