Agriculture Reference
In-Depth Information
conditions where crop production cannot succeed without irrigation. This
climate is found in North Africa, bordering the Tropic of Cancer, north-east
India, Australia and parts of the Pacifi c coast of South America. The coast of
Peru has arid plains and foothills and fertile river valleys. For example, average
annual rainfall for the town of Piura on the north-western coast is 51 mm,
and average minimum and maximum temperatures are 17.6°C and 30.5°C,
respectively. Thousands of hectares of land remained unproductive due to lack
of irrigation until large dams were built to produce hydroelectric power as well
as to provide irrigation.
ALTITUDINAL CLIMATES
Climates change with altitude at the same latitude, and the change is related to
temperature. The environment can be divided into three temperature zones at
the equator: the hot zone, from sea level to 1000 m; the temperate zone, from
1000 to 2000 m; and the cool zone, above 2000 m, with frost occurring at
approximately 5000 m at the equator. Temperatures in these zones dif er with
changes in latitude, prevailing wind patterns, precipitation and other factors.
In the Selva region of eastern Peru with large rivers, principally the
Amazon, two subclimates are recognized in terms of altitude and rainfall.
The low jungle or humid tropics extends from sea level to 800 m and has
rainfall throughout the year. The high jungle or central Selva, located between
800 and 1500 m above sea level, has a wet and dry climate, with about 6 to
7 months of wet season and the remainder with little or no rain. In the low
jungle, subsistence agriculture prevails, with crops such as cof ee, cacao,
banana, mango, papaya, pineapple, soursop, citrus, black pepper, cassava and
poma rosa ( Syzygium malaccensis ). Under large-scale commercial cultivation,
some of the traditional crops, such as mango, papaya, pineapple and citrus,
would do better at latitudes somewhat removed from the equatorial region,
having better soils and reduced disease problems associated with high rainfall.
The high jungle (wet and dry tropics) in the central Selva area of Peru is better
developed, with farms of large commercial size. Citrus (Valencias, mandarins
and limes) and cof ee have done well.
SUBTROPICS
Strict separation of tropical, subtropical and temperate climates is not
practical because of the many factors that infl uence climate. Even within
the geographical limits of the tropics, there are areas that are subtropical
and temperate, or even frigid, because of altitude, topography, ocean and air
currents. The subtropics occur between the two tropics and about 40° latitude,
with summers being hotter and winters cooler than in the tropics. Humidity is
 
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