Geoscience Reference
In-Depth Information
the past, insights for agricultural adaptation that confront us
today may well be found in the experience of how climatic
challenges were handled in the past. Historical analogues
about climate adaptation includes deliberate translocation of
crops across different agro-climatic zones, substitutions of new
crops for old crops and innovation of technology in response
to scarcity of resources (Easterling, 1996). An example of crop
translocation includes expansion of hard-red winter wheat
across climatic gradients of the North American Great Plains.
From 1920 to 1999, the northern boundary of hard-red win-
ter wheat expanded into a climatic region that was about 4.5°C
cooler and 20% drier than the climate for the wheat zone in the
1920s. Interestingly, the southward expansion of hard-red win-
ter wheat has not been as extensive where annual average tem-
peratures at the southern boundary are 2°C greater than those
of the 1920 southern boundary (Rosenberg, 1992; Easterling
et al., 2004). Thus, hard-red winter wheat has been adapted to
cooler and drier climates in the last 80 years. In China, winter
wheat planting has shifted from 38°54′N to 41°46′N. This shift
was aided by the introduction of freeze-resistant winter-wheat
variety from high-latitude countries (Chen and Libi, 1997).
The growth of soybean in Ontario, Canada illustrates
the examples of the substitutions of new crops for old ones.
Although soybean was cultivated in Ontario throughout the
twentieth century, it was not a prominent field crop until the
1970s. Between 1970 and 1997, the total acreage planted to soy-
bean increased by over 500%, with the expansion being attrib-
uted to a series of technological innovations made in response
to the climatic condition of Ontario (Smithers and Blay-Palmer,
2001). A fundamental climatic constraint to soybean cultiva-
tion in Ontario was the prevalence of cold night temperature
during flowering, confining soybean cultivation to the extreme
southwestern portion of the province. A key innovation to
address this constraint was the introduction of cold-tolerant
genetic material (
Fiskeby63
) from Sweden that led to the devel-
opment of
Maple Arrow
cultivar, which played a vital role in
the eastward spread of soybean crop. According to Smithers
and Blay-Palmer (2001), technological innovations were not
only confined to the development of cultivars but also to a range
of agronomic activities, including modification of planting time
and crop rotation-interrupted pest cycle, enhancing the cultiva-
tion of soybean.
The development of cowpea cultivars in the African Sahel
illustrates the examples of technological substitutions in
response to the existing variability in climatic resources. To
