Agriculture Reference
In-Depth Information
T A B L E 8.3. Weather Events Important in Food Production
Event
Average
High
Low
Effect
Temperature
8C(8F)
21 (70)
41 (105)
5 (41)
Plants cannot grow at low and do not
do well at very high temperatures
Rainfall
a
(mm)
1000
2000
500
Low rainfall results in insufficient
water for crop growth. High rainfall
results in high humidity and many
diseases
b
Wind
NA
50 km/h and
higher
NA
High wind can knock over crops and
prevent pollination
a
Ice, hale, and snow may also be problems in some areas.
b
Irrigation may be used to produce crops in low rainfall areas if there is a sufficient water source.
typically grown in all areas of the world where the warm season is long enough to allow
it to mature and there is sufficient water from either rain or irrigation.
Temperature, altitude, and rainfall are three climate factors that dramatically affect
crop and animal production. First and perhaps foremost is temperature, second is alti-
tude above sea level, which also controls temperature, and the third is rainfall (the
effects of these on crop production are summarized in Table 8.3). The length of time
during the year when the temperature is high enough to allow crop growth will, in
part, determine what crops can be grown and when. As altitude increases into the tropo-
sphere, the temperature decreases, affecting not only temperature but can also be
important in determining rainfall pattern and thus the crops and animals raised.
8.4.1 Temperature
Although some areas of the world experience high temperatures, generally high temp-
erature alone will not preclude crop growth. However, low temperatures, especially
those below freezing, will prevent crop growth. However, there are numerous food
plants that are temperature hardy
and thus can survive and even grow at quite
cold temperatures. In some cases crops may require low temperatures for initiation
of flowering, such as apples, or the color associated with the fruit, such as oranges.
As noted above the Earth can be divided into artic, subartic, temperate, semitropi-
cal, and tropical regions (Fig. 8.10) or into regions according to other schemes. It might
seem that simply knowing the latitude, above or below, the equator would be enough to
explain the temperature regime of an area. This is not the case for numerous reasons.
Ocean currents, prevailing winds, and altitude are three of the most important factors
in addition to latitude that help to determine the temperature regime of an area.
Weather along costal areas is strongly affected by ocean currents. In areas where
warm currents occur, such as those along the coast of Europe, these keep areas near
the sea warmer than might be expected. On the other hand in areas where cold currents
prevail, temperatures will be cooler than might otherwise be expected. The northern
The word hardy is used to indicate a plant or animal able to withstand harsh environmental conditions.
