WATER PRODUCTIVITY FOR HYBRID MAIZE UNDER IRRIGATED AGRICULTURE. Chittaranjan Ray, Director Nebraska Water Center, University of Nebraska

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1 WATER PRODUCTIVITY FOR HYBRID MAIZE UNDER IRRIGATED AGRICULTURE Chittaranjan Ray, Director Nebraska Water Center, University of Nebraska

2 OUTLINE OF TALK Global Food/Feed/Energy Demand The Challenge: Managing Water Resources Water Productivity in Corn Production Economic Water Productivity Spatial and Temporal Variability in Water Productivity Closing Productivity Gap Sustainability Concerns

3 POPULATION PROJECTION Current world populations of 6.9 billion is expected to reach 9.5 billion by 2050 Although Asia will have a major share of that population, the rate of population growth will be highest in Africa. By 2100, the share of world population in Africa will exceed 26% from its current share of 13% Worldwide, the middle class population is expected to reach 3.2 billion in 2020 and 4.9 billion in 2030 (with Asia having a lion s share of it). In Africa and Middle east, these number will be 220 and 340 million by 2020 and 2030, respectively.

4 DAILY CALORIE INTAKE VARY WIDELY

5 CALORIE INTAKE TREND

6 DIETS ARE CONVERGING TOWARDS MORE ANIMAL SOURCE FOOD China : Less than 5% of total diet : About 20% of total diet Spain : Less than 13% of total diet : About 25% of total diet Italy : Less than 13% of total diet : About 22% of total diet USA : Less than 28% of total diet : About 25% of total diet

7 MEAT CONSUMPTION AND GDP Affluence correlates well with meat consumption What is needed to produce more meat? Feed Water Energy

8 Food/Feed Increasing global consumption - - population growth, rising incomes, changing diets Limited opportunities for expansion in cropland Further limited by land degradation, non-food crops Yield increases reaching a plateau in many places Water Increasing competition by other water users principally cities (people and industry) Decreasing quality as well as quantity Increasing sustainability concerns (e.g., groundwater depletion) requires meeting environmental water needs Climate Change: Increasing variability in time and space

9 YIELD PLATEAUS FOR CEREAL CROPS Rice yield plateaued in South Korea since 1980 s and that in China since 2000, both at 8 tons/ha For wheat, Northwest Europe is seeing a plateau since 2000 at 7 tons/ha; in India a plateau is occurring little over 2 tons/ha from For irrigated corn, a plateau is occurring at 12 tons/ha in USA since 2005.

10 INCREASING SUSTAINABILITY CONCERNS In the High Plains Aquifer (United States), groundwater is being removed at a rate greater than natural recharge, leading to concerns about the long-term sustainability of agriculture.

11 WATER PRODUCTIVITY CONCEPT Water Productivity (WP) is defined as the ratio of net benefits from crop, forestry, fishery, livestock, and mixed agricultural systems to the amount of water required to produce those benefits (Molden et al. 2007). e.g.: total harvested Grain; total Biomass; total monetary value WP = Yield [kg; $] Water [m 3 ] e.g.: total Water applied to the field; Evapotranspiration; Transpiration

12 WATER PRODUCTIVITY EVALUATION IN NEBRASKA Water Productivity evaluation in irrigated corn production during nine consecutive years ( ). Each yellow point represents one quarter section from which field data about seasonal corn yields and applied irrigation water was collected.

13 WATER PRODUCTIVITY EVALUATION IN NEBRASKA Simulated maximum achievable yields per water supply compared to collected yield and water use data for each year ( ) and field (n=108) (left). Simulated and observed annual average WP for two districts in Nebraska (right).

14 CONCEPT AND SCALE CONSIDERATIONS OF WATER PRODUCTIVITY The concept of WP can help agriculture to produce more with less water Increasing WP not always desirable Environmental deterioration (fertilizer, pesticides) High investment costs (equipment, labor, etc.)

15 CONCEPT AND SCALE CONSIDERATIONS OF WATER PRODUCTIVITY Spatial Scale Plant/pot-, farm-, system-, basin- level lost water at one field (through seepage or runoff) can be used at another field of a basin reduced runoff at one field might come at the expense of ecosystems or at livelihoods somewhere else in the basin Temporal Scale Annual changing environmental conditions (e.g.: weather conditions) can cause temporal variations in WP Changing market values can cause variations in WP defined by monetary units

16 ECONOMIC WATER PRODUCTIVITY WP = Yield [$] Water [m 3 ] Input costs (e.g. Pumping costs for irrigation water) can be substracted but it is hard to account for all connected costs Big influence of the temporal variations of the market value of a crop declining WP with increasing depth to groundwater in Nebraska ( ) using different energy sources for pumping (Source: own elaboration).

17 ECONOMIC WATER PRODUCTIVITY Crop WP [kg/m³] Market Value WP [$/m³] Wheat $0.2 per kg Rice $0.31 per kg Maize $0.11 per kg Potato 3-7 $0.1 per kg Tomato 5-20 $0.15 per kg Onion 3-10 $0.1 per kg Physical and economic Water Productivity for selected crops (Adapted from Molden et al. 2007).

18 ECONOMIC WATER PRODUCTIVITY Crop WP in rain-fed Agriculture [$/m³] WP in irrigated Agriculture [$/m³] Almonds Barley Carrots Dates Figs Grapes Olives Oranges Potatoes Tomatoes Wheat WP of main crops in Tunisia at national level ( ) (Adapted from Chouchane et al. 2015).

19 STRATEGIES TO IMPROVE WATER PRODUCTIVITY Strategy Increasing yield Reducing Transpiration Reducing evaporation from soil and water Reducing runoff Practice Crop and resource management for enhancing yield Synchronizing water application with crop water demand Changing to higher value crops Crop selection to match season with low evaporative demand Deficit Irrigation Tillage and soil management (e.g.: minimum tillage, mulching) to reduce evaporation Water harvesting Tillage to increase inflitration Selected strategies to improve Water Productivity on field level (Adapted from Kijne et al. 2003).

20 NEBRASKA: A SUBSTANTIAL IRRIGATOR

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22 NEBRASKA WATER BALANCE ALLIANCE Variable rate irrigation Variable drive pumps Sensor controlled irrigation

23 VARIABLE RATE IRRIGATION

24 FOOD FOR ALL BY 2050? Improvements in crop genetics (salt and drought stress) Enhancing photosynthetic efficiency (to enhance yield for hybrids) still illusive! Enhancements in water use efficiency Crop modeling

25 SUSTAINABILITY CHALLENGES Managing nitrogen to reduce leaching to ground water and runoff losses Economics of treatment of nitrate in ground water from small communities and cost externalities Accounting for all forms of nitrogen in agriculture Nitrification inhibitors efficacy and their fate and transport Nitrate induced uranium mobilization in subsurface and remedies? Greenhouse Gas emissions (plowing, irrigation, harvesting, etc.)

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28 THANK YOU