Adapting Irrigated Agriculture to Drought in the San Joaquin Valley of California. Dr. James E. Ayars USDA-ARS SJVASC

Transcription

1 Adapting Irrigated Agriculture to Drought in the San Joaquin Valley of California Dr. James E. Ayars USDA-ARS SJVASC

2 Vital Statistics Length km Width 402 km Pop. 36,756,666 Economy $1.85 trillion Ag Economy - $36 billion Largest State economy 13% of US economy 7 10 largest in world

3 Geography of Water Conflict Central Valley Project moves water from the Sacramento Valley to SJV through the Delta. Water transported by San Luis Canal and has to be pumped from Delta into canal. Pumping restricted by environmental controls, e.g. smelt, salmon. CVPIA allocates 800,000 ac-ft of water for environmental flow through Delta. Water Supply Delta San Joaquin Valley Los Angeles

4 Aqueducts East side SJV Westside SJV

5 Drought A constant state of dryness No reasons supplied Climate Regulation Environmental Competing demands Municipal, Industrial Irrigated Agriculture

6 Droughts in California Climate Climate Climate CVPIA Climate & Regulation ? - Climate & Regulation

7 Adapting Productivity to Drought Goal Crop Production Annual (field crops) Perennial (tree and vine crops) Biomass or Fruit Relative Yield based on Relative ET 1- (Y c /Y m ) = K y (Et c /Et m ) Maximize T Eliminate E

8 Water Use Efficiency (WUE) Definition Yield per unit of water applied, delivered, or transpired. Goal maximize WUE NOT NECESSARILY MAXIMUM YIELD!!! Water Productivity

9 Water Productivity Wheat Thompson Seedless grapes

10 Crop Selection Annual Perennial

11 Annual - Seasonal considerations Cool - short Hot - long

12 Irrigation System Selection Goal Improve Irrigation Efficiency Ratio of Beneficially used to Applied water Beneficial uses ET, Cooling, Frost protection, Salt management To meet requirement Factor affecting Irrigation Efficiency Excess Deep Percolation Distribution Uniformity Poor irrigation water management Improper system selection and design

13 Switching Irrigation Systems Surface Sprinkler

14 Switching Irrigation Systems Hand move Sprinkler Self Propelled Center pivot

15 Switching Irrigation Systems Furrow Surface Drip

16 Switching Irrigation Systems Surface Drip Subsurface Drip

17 Larger Tubing Retrieval System

18 Factors in Selection Cost per acre (ha) to change from one system to higher technology Shift from low value to high value crops Improved technology enables transition GPS guided tractors, Larger drip tubing, Improved installation and retrieval systems for drip Improved spray packages on center pivots

19 Water Management

20 Climatic Irrigation Scheduling ET c = K c * ETo ET o = reference evapotranspiration (CIMIS) or Grass Lysimeter K c = crop coefficient

21 CIMIS Station Grass Lysimeter

22 Crop Water Requirements Lysimeter Crop Coefficients Garlic on WSREC Crop Lysimeter Kc and Canopy Cover Canopy Cover Kc (CIMIS) Kc (Lys) Garlic DOY

23 Deficit Irrigation Partial Root Zone Drying Irrigate one side of root zone and allow the other to dry out to induce stress response in portion of plant and thus reduce transpiration. Alternate sides to maintain health of plant. Requires additional equipment Requires soil with little soil water holding capacity. Regulated Deficit Irrigation Fully irrigate crop during critical growth periods and reduce irrigation during non critical periods. Requires knowledge of critical periods. Requires knowledge of water requirement during these periods. Decrease irrigation uniformly over season.

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25 Agronomy Improve storage of rainfall Mulching Fallowing Dry land farming Precision agriculture Planting, Fertilization Surface preparation, leveling, tailwater return Cultivar selection Planting Density

26 Alternative Water Supply Shallow Ground Water Salinity Source and control Treated Municipal Effluent Quality issues Infrastructure

27 Case Study

28 Annual Crop Production Year CVP Allocation (%) Cotton (ha) Tomato (ha) Lettuce (ha) Wheat (ha)

29 Perennial Crop Production Year CVP Allocation (%) Pistachios (ha) Grapes (ha) Almond (ha) Fallow (ha)

30 Water Allocations

31 Water Duty

32 Techniques Adopted in Westlands Water District Change cropping patterns from cotton to lettuce and vegetables Change irrigation from furrow to subsurface drip, sprinkler Trying dry land farming of grains Trying no-till and targeted production

33 Future Research Determine water and fertilizer interactions Deficit Irrigation Determine production goals related to water productivity Improve salinity management Implement subsurface drainage management Precision agriculture

34 Water by Fertilizer Interactions

35 Policy Implications Population projected to increase to 50 million people by Agriculture single largest user of water. How will water needs be met? Increase storage Eliminate agriculture Realize that California produces nearly 100% of several commodities grown in the US.

36 Questions

37 Acknowledgement - Photos Dr. Tom Trout USDA- ARS Dr. Charles Burt Cal Poly San Luis Obispo John Edstrom UCCE