Water Application Methods - Practices of Irrigation and On-farm Water Management - page 56

2.4 Selection of Irrigation Method

Decision must be made regarding the type of irrigation method before an irrigation
system is installed in a field. To choose an appropriate irrigation method, one must
know the advantages and disadvantages of the various methods. He or she must
know which method suits the local conditions best. Unfortunately, in many cases
there is no single best solution, as all methods have their relative advantages and
disadvantages. Trials of the various methods under the prevailing local conditions
provide the best basis for a sound choice of irrigation method.

2.4.1 Factors Affecting Selection of an Irrigation Method

Factors determining irrigation method are some in technical nature, some economic,
and others involve a close scrutiny of the operation and crop to be irrigated.
In selecting an irrigation method, the following factors should be considered:

• Soil type

• Field shape/geometry and topography

• Climate - evaporation rates, wind, and rainfall

• Water availability and its price

• Water quality

• The particular crop to be grown - physical requirements, crop layout, and water

use characteristics

• Required depth and frequency of irrigation application

• Labor requirements and its availability

• Energy requirement

• Economic factor - cost-benefit ratio, initial investment

• Compatibility with existing farm equipments

• Attainable irrigation efficiency of the proposed system

• Relative advantages and disadvantages of the available systems

• Type/level of technology at the locality

•

Cultural factor/previous experience with irrigation

•

Automation capacity

• Fertigation capability

• Environmental conditions - impact and regulations

• Farm machinery and equipment requirements

Soil Type

Light sandy soils are not well suited to furrow or basin irrigation systems. Sandy
soils have a low water storage capacity and a high infiltration rate. They therefore
need frequent but small irrigation applications, in particular when the sandy soil
is also shallow. Under these circumstances, sprinkler or drip irrigation are more
suitable than surface irrigation. On loam or clay soils all three irrigation methods