For reasons of economics and environmental quality, there is now a need to achieve greater efficiency in crop production with lower inputs. The key to lower economic and environmental costs is conservation. The amounts of water used for irrigation are large compared with the amounts used domestically. Small gains in efficiency in irrigation would produce significant increases in water available for other uses. Efficiency is important where competition for water makes it desirable to increase water supplies.
Efficiency also decreases the energy costs of pumping and providing water for irrigation.
Competition between irrigation and domestic uses is usually decided in favor of the latter, because the economic willingness to pay is higher for domestic uses. The allocation of water in southern California, U.S.A., in recent years is an example. Table 1 Irrigation efficiency factors 1. Conveyance efficiency - ratio of water delivered to water diverted from source 2. Application efficiency - ratio of water reaching the soil to water delivered 3.