On-farm Water Management: from efficiency to productivity

1. On-farm Water Management: from efficiency to productivity Theib Oweis Director of Integrated Water & Land Management Program International Center of Agricultural research in the Dry Areas

2. Southern Mediterranean Why improving efficiency? • Increased water scarcity • Declining agricultural water • Need for more food • Sustaining the ecosystems • Water for other sectors

3. Efficiency Output Efficiency =------------100% Input • Same units • Normally % • < 100% Implies losses during the process

4. Two groups of Efficiencies 1. Irrigation systems efficiencies • Application efficiency • Convenience efficiency • Storage efficiency 2. Farm or crop use efficacies • Water use efficiency • Transpiration efficiency • Farm water use efficiency

5. Typical furrow irrigation system

6. Transpiration Precipitation Evaporation Runoff Irrigation Storage Seepage Drainage Deep percolation Field water balance

7. Water stored (mm) Application Efficiency---------------------------x100% Water applied (mm) • Reflects losses in deep percolation and runoff • Does not reflect root zone satisfaction • %

8. Water stored (mm) Storage efficiency= -----------------------------100% Water needed (mm) • Reflects how full is the root zone • Ignores deep percolation • %

9. Water delivered to farm Conveyance eff. = ------------------------------100% Water diverted from source • Reflects seepage, evaporation and weeds use losses • %

10. One can under irrigate No DP / 100% application Eff 50% storage Eff. One can over irrigate 100% storage efficiency 50 % application efficiency Sprinkler irrigation

11. Over irrigation • Application eff. 50% • Storage eff. 100% Trickle irrigation • Under irrigation • Application eff. 100% • Storage eff. 50%

12. Issues of irrigation efficiencies • Reflects the performance of irrigation system (engineering aspects) • Ignores recoverable losses ??? • Nothing to do with the return to water • Wrongly used to judge the whole farm water management system

13. Farm Efficiencies Production (Kg) WUE = ---------------------------- Water used ( m3) Units are mainly production / volume of water No standard type of production (biomass, grain, roots ???) No standard water used (applied, stored, ET, ???)

14. Biomass production (kg) Transpiration Eff.= --------------------------------- Transpiration (mm) Ignores evaporation losses Reflects plant performance Not %

15. New concept (Shideed, Oweis and Gabr 2000) Water required to produce (x) in mm Farm WUE = --------------------------------------------------100% Water used to produce (x) in mm • Reflects farmer’s performance • Considers local environment specifity • Can be used for farm multi-cropping • %

16. Transpiration Precipitation Evaporation Losses Runoff recoverable Irrigation Storage Seepage recoverable Drainage Partially recoverable Quality losses Deep percolation To ground water recoverable Field water balance

17. Issues of irrigation losses • Recoverable losses: • are not real / only on paper losses • economic issue at the farm (cost to recover) • management issue at the scheme and basin • + or - environmental issues (leach out salts) • Real losses may not be recovered: • Evaporation • Transpiration (productive) • Non beneficial uses (weeds)

18. What return ?? • Biomass, grain, meat, milk (kg) • Income ($) • Environmental benefits (C) • Social benefits (employment) • Energy (Cal) • Nutrition (protein, carbohydrates, fat) • What water ?? • Quality (EC) • Location (GW depth) • Time available • Consumed (depleted) • Evaporation • Transpiration • Quality deterioration Water productivity: a broader framework Return WP = --------------------------------- Unit of water consumed

19. Saline water equivalent Oweis et al 2011

20. Potential water productivityimprovement

21. Scales and drivers to increase WP • At the basin level: • competition among uses (Env., Ag., Dom.) • conflicts between countries • Equity issues • At the national level: • food security • hard currency • sociopolitics • At the farm level: • maximizing economic return • Nutrition in subsistence farming • At the field level: • maximizing biological output

22. Max WP Max Yield Tradeoffs between water & land productivity

23. Potential WP improvements • Reducing evaporation • Improving management • Enhancing genetic resources • Great potential in developing countries

24. What to grow under scarcity ?? • Traditional farming: hard to change • Water productivity: what productivity ?? • National food security, self sufficiency • Virtual water ???

25. Potential practices • Supplemental irrigation • Deficit irrigation • Germplasm • Cultural practices • Water harvesting

26. Irrigated agriculture • Increasing water productivity • Deficit irrigation • Modifying cropping patterns • Cultural practices • Management of marginal water and soil • Secondary salinity • Reuse of treated wastewater • Improving irrigation systems performance

27. Modernizing irrigation: water savings ! • Does irrigation modernization save water ? • YES • Does increasing Irrigation Efficiency from 50% to 80% save 30% water? • NO • How much saving then? Depends on: • System changed and system adopted • Irrigation management • Crops and pattern • Mostly in reducing evaporation and non beneficial use • Needs assessment • Is it worth the cost? Needs research

28. Modern systems: productivity • Higher productivity is not only associated with water savings. Drip irrigation does: • Provide better soil water due to frequent irrigation • Fertigation more frequent and uniform • Weed control through • The cost: • Investment, Maintenance, Skill • Salt accumulation needs periodical flushing • Modernizing surface irrigation, very good idea