2014_09_19_seminar_Dr_Perrry_Cabot_can_ag_be_efficient_sustained.pdf

Irrigation Efficiency and ConservationCan agriculture be efficient? Can it be sustained?

2014 Annual Water Seminar: Colorado River DistrictDr. Perry Cabot, Colorado State University

Grand Junction, COSeptember 19, 2014

The three things that we have taken to be the natural state of our water supply –abundant, cheap, and safe – will not be present together in the decades ahead.

We are on the verge of a second modern water revolution.

The Big Thrist (2011)

Fishman, C. 2011. The Big Thirst: The Secret Life and Turbulent Future of Water. Free Press: New York, NY. 2

SOURCE: http://www.nationalgeographic.com/foodfeatures/feeding-9-billion/ 3

Food is critical to our population.

Thank you, Captain Obvious!

Accomplishing this feat will require innovative uses of technology, management (people), natural

resources and policy.

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The basin and statewide dialog deals with how agriculture can contribute (water) to address

existing shortages.

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Two basic strategies:

Conservation and Efficiency

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The terms conservation and efficiency are often used

interchangeably, leading to confusion of methods to address

water shortages.

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Defining these terms is important to correctly inform the societal views

of irrigated farming and its benefits,

… supplying high quality, abundant food to feed our growing population.

Howell, T.A. 2003. Irrigation Efficiency. Encyclopedia of Water Science. Marcel Dekker: New York, NY. pp 467-472. 9

Let’s take a look at conservation.

Conservation is about reducing crop, field or farm water demand.

There will be a downward effect on yields (for similar crops).

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Conservation by row-crop fallowing

Irrigation Water Supply

Consumptive Use

Return Flow

Conserved CU Water

“Saved” Water

Because the crop is gone, fallowing obviously lowers yields.• EXAMPLES: Compensated rotational fallowing, Leasing,

Change of use, Buy-and-Dry+ break disease cycles, soil health, retire marginal lands, shift

the crop mix‒ without proper transition, soil conditions could worsen

Corn Field

Soil Moisture Deficit?

Fallow Field

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Conservation by “deficit” irrigation

Irrigation Water Supply

Consumptive Use

Return Flow

Conserved CU Water

“Saved” Water

For a given yield goal, a conservation approach alone will result in lower yields.• “Doing less with less” (Less yield « » Less diversion)+ foster targeted irrigation to critical growth stages‒ riskier, challenges in water court?

Yield Loss

Alfalfa Field

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Conservation by “split-season” irrigation

Irrigation Water Supply

Consumptive Use

Return Flow

Conserved CU

“Saved” Water

Split-season irrigation is another conservation approach • “Doing less with less” (Less yield « » Less diversion)+ administratively easier because diversion does not take place,

quicker in effectiveness against shortages‒ soil moisture forbearance, nematodes, forage quality

Yield Loss

Alfalfa Field

Soil Moisture?

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Now let’s take a look at efficiency.Efficiency is about reducing water

losses.Conversion of potential benefit into

actual benefit.

Effect on yields should be negligible or even positive.

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Basic Definition: Irrigation Efficiency

Quantitatively, efficiency is the ratio of the volume of water which is beneficially

used to the volume of irrigation water applied.

ASCE. 1978. Describing Irrigation Efficiency and Uniformity. Journal of the Irrigation and Drainage Division. 104: 35–41. 15

Irrigation Concepts

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Efficiency by Tech or Management

Irrigation Water Supply

Consumptive Use

Return Flow“Saved” Water

For a given yield goal, an efficiency approach alone has the goal of maintaining yields.• “Doing the same with less” (Same yield « » Less leakage)+ yields can improve, labor costs lower, change to crop mix,

buffer drought and climate change, water quality improvement‒ higher cost, learning curve, system pressure must support

Alfalfa Field

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Research has already proven that greater efficiencies are entirely possible.

Farmers need reasonable incentives.

Expected Irrigation Efficiencies

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Sprinkler Irrigated Land

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Simple Irrigation Scheduling

• Employ tools for soil moisture monitoring

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Irrigated Corn

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Irrigated Corn

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Conservation versus Efficiency

Efficiency Strategy

Consumptive Use

Return Flow“Saved” Water

Alfalfa Field

Conservation Strategy

Consumptive Use

Return FlowConserved CU Water

“Saved” Water

Yield Loss

Alfalfa Field

No yield loss or increase yield

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Simultaneously practicing conservation and efficiency is possible.

New crops bring new risks.

Alternative Crops or Vanguard Cropping

Consumptive Use

Return Flow

Conserved CU Water

“Saved” Water

For a given yield goal, a conservation approach alone will result in lower yields.• “Doing something different with less” (New « » Less diversion)• Introduces profitability as an issue – what kind of condition are

we trying to maintain? Cash flow? Is there a market?

Alternative Crops

Glennon, R. 2009. Unquenchable: America’s Water Crisis and What to do About it. Island Press: New York, NY. 26

Alfalfa Cropping in California

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Irrigation Scheduling with Telemetry

Saha, R., S. Raghuwanshi, S.K. Upadhyaya, W.W. Wallender, D.C. Slaughter. 2011. Water sensors with cellular system eliminate tailwater drainage in alfalfa irrigation. California Agriculture. 65(4): 202-207. 28

Arnold, B.J., S.K. Upadhyaya, J. Roach, P.S. Kanannavar, D.H. Putnam. 2014. Water advance model and sensor system can reduce tail runoff in irrigated alfalfa fields. California Agriculture. 68(3): 82-88.

Reduced tailwater runoff to 5-10% of applied water

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Onion Farming in the Uncompaghre

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NoChicoBrush (NCB) Site Design

System 1 - Drip

System 2 - Furrow

Base Station

Onion field near Olathe, CO

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Water Budget

Metered Irrigation Monitoring

Tailwater Flume Monitoring

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NoChicoBrush (NCB) Site DataSite Name Acreage Metered Rainfall Irrigation Actual ET

Furrow - Field Corn 1.6 63.1 ac-in 3.7 in/ac 39.4 in/ac 23.8 in/ac

Sprinkler - Field Corn 46 1321.7 ac-in† 3.7 in/ac 28.7 in/ac 23.8 in/ac

Furrow - Onion 1.0 32.1 ac-in 5.0 in/ac 32.1 in/ac 20.8 in/ac

Drip – Onion 28 547.5 ac-in 5.0 in/ac 19.6 in/ac 24.7 in/ac

ASCE (1978) Irrigation efficiency (IE) calculated against Penman-Kimberly ETc (Wright, 1981).• Furrow and Sprinkler IE values for corn fields = 51% vs 70%• Furrow and Drip IE values for onion fields = 50% vs ~99%

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57440

68106

50000

55000

60000

65000

70000

Furrow Irrigation Drip Irrigation

Yiel

d (lb

/acr

e)NoChicoBrush Irrigation Research Sites

(onions planted 4/5/2014)

IWUE (furrow) = 1790 lb in-1

IWUE (drip) = 3774 lb in-1

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0

1000

2000

3000

4000

5000

6000

Colossal Jumbo Medium Pre-Pack

Tota

l Cou

nt

Onion Size Category

NoChicoBrush Irrigation Research SitesFurrow Irrigation Drip Irrigation

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Farming in the Future

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Remote Sensing of ET in Agriculture

Final Thoughts

Twenty years ago, did you think you’d be carrying a phone in your pocket?

How about a computer?

We used to think “the cloud” was just water vapor!

Underlying this technology is the societal trend towards efficiency.

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Eating patterns will likely shift.

The next generation of farmers will be more efficient tech-driven.

In next 50 years, humans must produce as much food as has been produced in history.

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