Agriculture Reference
In-Depth Information
Figure
8.14.
Strawberries
and
flower
production
in
the
Banget
Valley
near
Baguio,
Philippines.
This illustrates that the altitude at which the agricultural activity is taking place
has a strong effect on the type of agriculture practiced and the types of crops grown.
Cold-weather crops such as cabbage, snow peas, and strawberries are grown both at
high latitudes and at high altitudes. Many high-altitude areas are steeply sloping, have
little soil and are thus not suitable for most types of agricultural production. However,
such
areas
may
be
planted
to
various
types
of
tree
or
bush-type
plants
for
fruit production.
8.4.3 Precipitation
Rain can be heavy as in tropical areas, which get 2000รพ mm of rain a year, or very little
such as deserts with 200 mm or less of rain a year. In addition to the amount of rainfall,
the time of year when it occurs and its intensity are also important. Rain can fall during
months when crops are not planted and stored in the soil for plant use later in the
growing season provided there is enough rain to allow significant soil storage. On
the other hand small amounts of rain can come only during the growing season and
thus be a limiting factor in crop production. The amount of grain, fruit, and vegetables
produced are being largely determined by this rainfall. This, of course, assumes all
rain-fed agriculture with no irrigation.
In addition to the quantity, the fate of precipitation after it falls is extremely import-
ant. It can infiltrate into the soil and just wet the soil profile. It can be greater than that
required to wet the profile and drain or percolate below the soil and be stored in the
subsoil; it may also be so little that all precipitation that infiltrates into the soil is sub-
sequently lost from the soil surface when the soil dries. As mentioned above, water is
lost from soil by both evaporation from the soil surface and by transpiration through
plant leaves. The combined losses are termed evapotranspiraion. For successful crop
production it is essential that there be enough water in the soil to provide for both
the crop needs and the water lost by evaporation. If insufficient water is available,
crop growth will decrease and yield will be lost.
