Agriculture Reference
In-Depth Information
Figure
10.22.
Irrigation furrows.
little over- or underapplication. There is no need to level a field. Some sprinkler systems
are used on orchards in hilly fields where furrow irrigation would be extremely difficult.
In vegetable crops, fertilizers may be mixed with the irrigation water to supply nutrients
with the water. In general, sprinkler irrigation requires a bit less attention in the field
than furrow irrigation. A farmer will set a section of pipe with sprinklers and let it
operate for a few hours before moving it to the next location in the field. In fields
with a sandy soil, furrow irrigation results in too much loss of water and sprinkler irriga-
tion must be used.
A disadvantage of sprinkler irrigation is the equipment needed to install a system.
It requires a high-volume, high-pressure pump, long sections of easily disassembled
aluminum pipe, and special nozzles to uniformly apply water to the crop. Some very
large commercial farmers use a type of sprinkler system called center pivot. In these
systems the field is circular and the irrigation pipe is mounted on large wheels. The
entire assembly turns around a well and pump located in the center of the field.
These systems need even less attention than the sprinkler system shown in
Figure 10.23. In very dry areas, the loss of water by evaporation may be significant.
Sprinkler irrigation may not be recommended for some crops in certain areas since it
wets the leaves, creating an ideal environment for growth of fungal diseases.
10.15.3 Drip Irrigation
The system of drip irrigation is a relatively recent invention, being invented in 1965 in
Israel. The basic system consists of small tubes carrying water to evenly spaced “emit-
ters,” or drippers. These emitters release water drop by drop to the base of each plant.
The result is a very steady application of just enough water to each plant to permit
maximum growth with no excess of water.
Drip irrigation systems are normally used on high value vegetable and fruit crops
such as tomatoes or peaches. An advantage of drip irrigation is that crops yield more
using less water than other irrigation methods. This is especially important in dry
