Irrigation Efficiency Issues to consider Ian McIndoe

1. Irrigation EfficiencyIssues to considerIan McIndoe

2. What Does Irrigation Efficiency Mean? It means different things to different people • Some of the main points are: • It needs to be applied to an area with defined boundaries • It needs to be considered over a given time-frame, eg an irrigation season • It is related to the volume of water taken from the source that is beneficially used • It needs to take into account soil water storage and effective use of rainfall • It should consider all uses within the area There is no single definition that covers all aspects of irrigation efficiency

3. On-Farm Irrigation Efficiency Farmers need to consider many factors such as: • Water • Water supply • Application efficiency • Environmental issues • Energy • Labour • Capital investment The level of efficiency that can be attained is a compromise between many factors

4. Examples of Typical Measures • Application efficiency = Water stored in root zone • Water supplied to field • Energy efficiency = Energy used for irrigation • Total annual water use • Labour efficiency = Irrigation time • Irrigation + O&M time • Water use efficiency = Annual production • Total annual water use • Capital efficiency = Return on investment You can’t look at these factors in isolation to measure or assess irrigation efficiency.

5. Where are the “Losses” These are the water losses expected on typical spray irrigation systems: • Leaking pipes <1% • Evaporation <5% • Blown away by wind <5% • Watering non-irrigation areas <2% • Interception <2% • Surface runoff <5% • Uneven/excessive application 5-30% The focus is often in the wrong areas, ie visible versus non-visible.

6. Attaining High Efficiency Depends on • The design of the system • How well it is managed • Design sets the platform for efficient Irrigation • If poorly designed, get low efficiency • If properly designed, potential for high efficiency

7. What Drives Farmers to use Water Efficiently • Profitability • Sustainability • Maintaining access to markets • Maintaining access to water • Limited supply of water • Environmental effects • Environmental pressure • Change of land ownership • Change of enterprise type • Cost of water

8. What Constrains Efficient Irrigation • Unreliable water supplies • Lack of supply or operational flexibility • Unwanted stoppages • Limited user training • Poor design • Limited or no system auditing • Limited or no soil moisture measurement • Limited or no use of irrigation performance measures

9. Factors Contributing to Improved Irrigation Efficiency • Attitude – normal farm input, not just drought insurance • Planned inputs delivering planned outputs • Design of farm around irrigation system - layout • Optimal use of labour, capital and energy • Systems matched to range of soil and plant requirements – good design, on-demand supply • Piped water schemes, use gravity as much as possible • Measurements and monitoring for good operation • Good maintenance • Use of performance measures

10. Some things to look for • General impression • Operator experience and know how • System flexibility – matched to crop/soil requirements • Application uniformity and intensity • Good maintenance • Water and soil moisture measurement and use of information • How rainfall is used – risk management • Record keeping

15. Travelling gun, soft hose

16. Hard hose gun

17. Long lateral

18. Solid set

19. K Line

20. Fixed boom, soft hose

21. Rotary boom, soft hose

22. Centre-pivot

23. Spinner

24. Border-dyke