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

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

Output Efficiency = % Input Same units Normally % < 100% Implies losses during the process Efficiency

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

Typical furrow irrigation system

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

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

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

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

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

Trickle irrigation Under irrigation –Application eff. 100% –Storage eff. 50% Over irrigation –Application eff. 50% –Storage eff. 100%

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

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, ???)

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

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

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

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)

Water productivity: a broader framework Return WP = Unit of water consumed 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

Saline water equivalent Oweis et al 2011

Potential water productivity improvement

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

Tradeoffs between water & land productivity Max WP Max Yield

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

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

Potential practices Supplemental irrigation Deficit irrigation Germplasm Cultural practices Water harvesting

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

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

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