Water Application Methods - Practices of Irrigation and On-farm Water Management - page 59

Compatibility with Existing Farm Equipments
Choose a system that is compatible with your farming operations, equipment, field
conditions, and crops and/or crop rotation plan.
Attainable Irrigation Efficiency of the System
Water application efficiency is generally higher with sprinkler and drip irrigation
than surface irrigation, so these methods are preferred when water is in short supply.
However, it must be remembered that efficiency is just as much a function of the
irrigator as the method used.
Relative Advantage and Disadvantages of the Available Methods
Several irrigation systems are on the market. Each system has advantages and dis-
advantages. A discussion of suitability/capabilities of different systems has been
explained earlier. These points should be taken into consideration.
Crop to Be Irrigated/Type of Crop
The crop type influences the selection of the irrigation method. Surface irrigation
can be used for all types of crops. Sprinkler and drip irrigation, because of their
high capital investment per hectare, are mostly used for high-value cash crops, such
as vegetables and fruit trees. They are seldom used for the lower value staple crops.
Widely spaced crops do not require total field soil volume to be wetted, and thus
basin or border irrigation in this case is less useful. Instead, a mini-basin can be
formed around each tree. Drip irrigation is suited to irrigating individual plants or
trees or row crops. It is not suitable for close growing crops (e.g., paddy). Paddy
(rice) is always grown in basins. Many other crops can also be grown in basins (e.g.,
maize, sorghum). If paddy is the major crop, basins will be the logical choice. Those
crops that cannot stand a very wet soil for more than 12-24 h should not be grown
in basins. Row crops such as maize, vegetables, and trees are best suited to furrow
irrigation. Close growing crops such as wheat, mustard, and alfalfa are best suited
to border irrigation.
Required Depth and Frequency of Irrigation Application
The depth of water (mm) required per irrigation and seasonal total water require-
ment influence the irrigation method. Field experience has shown that most water
can be applied per irrigation application when using basin irrigation, less with bor-
der irrigation, and least with furrow irrigation. Usually 40-70 mm of water is applied
in basin irrigation, 30-60 mm in border irrigation, and 20-50 mm in furrow irriga-
tion (in large-scale irrigation projects, the amounts of water applied may be much
higher). This means that if only little water is to be applied per application, e.g., on
sandy soils and a shallow rooting crop, furrow irrigation would be most appropriate.