Getting by with Less Water in Trees & Vines UNIVERSITY of - - PowerPoint PPT Presentation

Getting by with Less Water in Trees & Vines

UNIVERSITY of CALIFORNIA COOPERATIVE EXTENSION

Blake Sanden -- Irrigation & Agronomy Farm Advisor Kern County Drougth Preparedness Workshop DWR-CIT Fresno Dec. 17, 2013

3 foot push or slide hammer probe ($150-$250)

Hand-powered twist augers ($150 - $300)

Tensiometer The first “at a glance” in-situ soil moisture sensor ($60-$90, depending on length)

A device using low levels of radiation, the neutron probe, was developed in the 1960’s for checking soil moisture. Used mostly by researchers and irrigation consultants, it is often the standard check for the accuracy of other instruments. Largest sample “volume” to estimate moisture.

Watermark blocks estimate soil moisture tension (matric poten- tial) using electrical resistance and require no maintenance (~$30). However, a separate meter or logger ($200+) is needed to read the device.

Dozens of new soil moisture sensors and logger combinations have come on the market in the last 10 years

Real-time data transmission and analysis over the internet can be convenient and sometimes fustrating and confusing at the same time.

Field loggers that simply record data have to be downloaded but are much cheaper than web-based systems (Loggers used in Kern County irrigation projects)

Where do I monitor in these large-scale fields?

Where do I monitor?

How many sensors are enough? What type is best for which crop?

Soil Moisture Monitoring in Citrus

Installing Watermark blocks and a Hanson AM400 logger in citrus

Fine silty soil and a good shot of water down the hole improves contact with soil pores. Good capillary movement of water is what makes these sensors work.

Loggers used in Kern County irrigation projects

Understanding mid-season soil moisture trends in citrus using Watermark Blocks Microsprinkler Irrigation

10 year old trees (10x20'), 12 gph Fanjet, 24 hr sets

• 60
• 50
• 40
• 30
• 20
• 10

6/8 6/22 7/6 7/20 8/3 8/17 8/31 9/14 Soil Moisture Tension (cb)

15" 30"

"0 cb" rdng & sharp dropoff indicate saturation & leaching Perfect recharge to 30" with no leaching 36 hr set & recharge to 30" with slight leaching Deficit irrigation and slow loss of moisture Uphill side of hose. Densest planted part of block.

(a)

(Page 10)

Mature Trees (15x20'), 12 gph Fanjet, 24 hr sets

• 60
• 50
• 40
• 30
• 20
• 10

6/8 6/22 7/6 7/20 8/3 8/17 8/31 9/14 Soil Moisture Tension (cb) 15" 30" Set 1-- Good hose pressure. Loamier ground than set 2. Possibly too wet, but trees look great and grower used less water than previous year. Foliage on tree skirt also reduced throw of water. Drainage at the 15" depth takes about 3 days before normal crop water use commences. Possible deep percolation below 30".

(b)

Mature trees (15x20'), 12 gph Fanjet, 24 hr sets

• 60
• 50
• 40
• 30
• 20
• 10

6/8 6/22 7/6 7/20 8/3 8/17 8/31 9/14 Soil Moisture Tension (cb) 15" 30" Set 2 -- Lower pressure than set 1 and sandier ground. No leaching past 30" but refill adequate. Same row as set 1.

(c)

Soil Moisture Changes in Citrus Under Different Set Pressures

(Page 10)

Citrus, Row 9 Hose End Delano Loam with Coarse Sand

• 200
• 175
• 150
• 125
• 100
• 75
• 50
• 25

3/11 3/25 4/8 4/22 5/6 5/20 6/3 6/17 7/1 7/15 7/29 8/12 8/26 9/9 9/23 10/7 10/21 11/4 11/18

Soil Moisture Tension (cb) 18" 36" 60" Citrus, Row 8 Near "T" Delano Loam with Coarse Sand

• 200
• 175
• 150
• 125
• 100
• 75
• 50
• 25

3/11 3/25 4/8 4/22 5/6 5/20 6/3 6/17 7/1 7/15 7/29 8/12 8/26 9/9 9/23 10/7 10/21 11/4 11/18

Soil Moisture Tension (cb) 18" 36" 60"

Drip Irrigation with excessive frequency and duration in a loam/clay loam soil

2004 - Flood Almonds Kimberlina Sandy Loam

• 200
• 180
• 160
• 140
• 120
• 100
• 80
• 60
• 40
• 20

4/3 4/17 5/1 5/15 5/29 6/12 6/26 7/10 7/24 8/7 8/21 9/4 9/18 10/2 10/16 10/30 Soil Moisture Tension (cb) 15" 30" 48"

CONTROL Estimate 41 inches infiltration

2004 Watermark Readings -- Flood Almonds, 19th Leaf, Kimberlina Sandy Loam

• 200
• 180
• 160
• 140
• 120
• 100
• 80
• 60
• 40
• 20

4/3 4/17 5/1 5/15 5/29 6/12 6/26 7/10 7/24 8/7 8/21 9/4 9/18 10/2 10/16 10/30 Soil Moisture Tension (cb) 15" 30" 48" (Sensors moved near edge

• f berm.)

Sensors @ 18, 36 and 60" depths, middle of drive. Poor infiltration due to tractor wheel

• compaction. Profile slowly

drying out.

GYPSUM Estimate 44 inches infiltration

But what does soil moisture “tension” tell us about the actual amount of water depletion?

• How big is the cup (soil AWHC)?
• How thirsty is the crop (ET)?
• How often/much do you fill the cup?

A device using low levels of radiation, the neutron probe, was developed in the 1960’s for checking soil moisture. Used mostly by researchers and irrigation consultants, it is often the standard check for the accuracy of other instruments. Largest sample “volume” to estimate moisture.

Electronics, data loggers and multi-stage sensors can increase the cost rapidly up to $5,000 to $10,000. The need for this degree of sophistication is debatable.

6 hrs. 4 hrs. Rain 4-inch dries out Day-night stepping indicates root activity at 10, 20, 30 cm No root activity at 20 & 36-inch levels (no stepping) Rains

Separate Layer Graph

Equipment for checking soil moisture

• Most Common Method

Does High Tech Irrigation & Research Guarantee Profit & Sustainability?

51st CA Irrigation Institute “Embracing Innovation: the Next Generation” February 4-5, 2013 Blake Sanden – Irrigation Advisor, Kern County http://cekern.ucdavis.edu/Irrigation_Management/

What are grower “sense” abilities regarding high-tech inputs for ag?

• 1. Farmers are the most common sense people around.
• 2. Farmers will adopt practices that make money, but …
• 3. They tend to only use practices that they feel they

understand and can sensibly/practically incorporate into their ranch operation.

• 4. Information on “soil moisture sensor” technology is

confusing and overabundant: >50,000 Google hits in 2003 and >1,000,000 hits in 2013.

• 5. Performance of many soil moisture and other field

sensors has often been inconsistent.

The “science” on adoption is lacking!

• 5. Irrigation academics and engineers don’t like to study

people! Out of 274 presentations and posters combined at the 1996 and 2000 big quadrennial irrigation meetings of the ASAE only 8 presentations dealt with technology transfer and adoption.

• 6. ULTIMATE

ECONOMIC PRINCIPAL: if it makes money it will be done!

… and this much monitoring technology?

PureSense Comprehensive Soil Moisture &Irrigation Summary for Almonds

Web-based reporting?

Location of salinity trial California Aqueduct

Lerdo Highway Belridge Oilfield

Do I need aerial / satelite imagery …

NDVI and % cover from 4 color digital aerial imagery captured at a 1 foot pixel resolution 8/14/12

(differences are statistically significant)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 % Cover All Plot NDVI Canopy NDVI NDVI, % Cover EC 0.5 EC 3.2 EC 5.2

… and spectral analysis for

• ptimal

irrigation?

The whole Central Valley covers Zones 12 to 16: for an “normal year” ETo

• f 53.3 to 62.5 in/yr,

with most area @ 53 to 58 inches. CIMIS – CA Irrigation Management Information Service

Nothing like a locker box full of electronics to “simplify” irrigation!

David A. Goldhamer, Elias Fereres California Agriculture May-June 2001 pp32-37

Does all this stuff guarantee profit and “sustainability”? YES (maybe?) …

NO … DEPENDS …

• 1. For ALL crop settings/fields? Definitely NO!
• 2. Do we have “silver bullet” criteria that will tell me

what technology will guarantee profitability for given field conditions? NO!

• 3. Are there guidelines to know what technology is

helpful for what areas/problems? YES!

• 4. Is there a “high-tech” ag consultant out there who

can “get it right” every time? Only GOD!

• 5. I am not God, nor is any irrigation company or

even the Regional Water Quality Control Board!

ANSWERS / DISCLAIMERS:

And what the heck is “sustainability” anyway?

• Long term profit? (Absolutely!)
• No degradation of groundwater, no

leaching?

• Increasing soil organic matter & “CO2

sequestration”?

• Use less water, chemicals, be “greener”?

ELECTRON MICROGRAPH OF STOMATA ON THE UNDERSIDE OF A LEAF. Reduced water, deficit irrigation, causes less turgor pressure in the plant, reduces the size of stomatal

• penings; thus decreasing the uptake of carbon

dioxide and reducing vegetative growth.

What’s the promise of “high tech” irrigation?

KNOWLEDGE: a way

to look into and quantify the crop rootzone & plant nutrient/water status, which leads to…

• Increased efficiency
• Increased yield
• Decreased inputs (maybe)
• Increased profit – the

universal goal!

TO MEASURE IS TO KNOW

On October 25, 1791, Washington appealed a third time to Congress, "A uniformity of the weights and measures of the country is among the important objects submitted to you by the Constitution and if it can be derived from a standard at once invariable and universal, must be no less honorable to the public council than conducive to the public convenience.” It was not until 1838 that a uniform set of standards was worked out.

Is precision/standards of measure- ment a 20th century concept?

For high yields we must control & monitor the “natural factors” but all these factors and their measurement have large variability:

• Applied Water +/- 3% (flow meter variability)
• Net Radiation / Photosynthetically Active

Radiation (PAR) +/- 15%

• Plant stress / Stem Water Potential (SWP) +/- 10%
• Stomatal Conductance +/-15%
• Rootlength density +/- 50%
• Soil moisture “tension” (matric potential) +/-25%
• Soil water content (%, inches/ft) +/-25%

(Sanden ballpark error estimates for example only.)

What about cumualtive error?

National Institute of Standards & Technology (Thank you George Washington!) most used formula for engineering errors: Statistically – a sort of pooled variance

Example using Watermark electrical resistance blocks for Soil Moisture Tension (matric potential)

A variety of loggers can be used for various sensors: Costs from $100 (Hobo) to $5,000 (Campbell)

Siting logger and soil moisture monitoring equipment near micro sprinkler and tree in 5th leaf almonds. (Chart @ 18” depth.)

A40 Fanjet

18" Gyp. & Control.

gypsum in/ft = 3.88cb-0.2732 R2 = 0.6834

• ctrl. In/ft = 0.46cb0.1777

R2 = 0.2162

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 25 50 75 100 125 150 175 200 Matric Potential (-cb) Water Content (in/ft) Gypsum Control

Soil moisture release regres- sions using neutron probe water content as a function

• f Watermark

matric poten- tial readings. Not all instal- lations of Watermark sensors perform the same in the same soil type.

18" Flood Almonds 150' & 800'.

150' in/ft = 5.94cb-0.3646 R2 = 0.8546

800' in/ft = 4.52cb-0.3355 R2 = 0.842

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 25 50 75 100 125 150 175 200 Matric Potential (-cb) Water Content (in/ft)

150' 800'

Same tree spacing and flood irrigation on same soil type only ¾ mile away from below orchard. Wasco Sandy Loam

No correlation of bulk soil water content and Watermark readings for “Control”.

Example:

How accurate is our estimate of soil water content estimated using a tensiometer and applied water monitored at a given spot for estimating the irrigation schedule for the whole field?

• Applied Water +/- 3% (flow meter variability)
• Rootlength density +/- 50%
• Soil moisture “tension” (matric potential) +/-25%
• Soil water content (%, inches/ft) +/-25%

For simplicity assume df/dxn = 1 Total error (%) = 100(0.03^2+0.5^2+0.25^2+0.25^2)^0.5 = 61.3%

OUCH!!

So you’re saying that just kicking the dirt

• r flipping a coin to make the irrigation

schedule will have less error than using some kind of high-tech monitoring? So accuracy of absolute numbers for the whole field is a problem. Is there value to the “trends” observed from a given site?

Almond (Fritz) Sandy clay loam

• 180
• 150
• 120
• 90
• 60
• 30

3/15 4/5 4/26 5/17 6/7 6/28 7/19 8/9 8/30 9/20 10/11 11/1 Soil Moisture Tension (cb) 18" 36" 60" Almond (Non Peril) Sandy clay loam

• 180
• 150
• 120
• 90
• 60
• 30

3/15 4/5 4/26 5/17 6/7 6/28 7/19 8/9 8/30 9/20 10/11 11/1 Soil Moisture Tension (cb) 18" 36" 60"

Watermark Readings from AM400 logger, reading 3x/day

FRITZ NONPARIEL 2038 lb/ac yield and 44.8 inches irrigation 2478 lb/ac yield and 45.0 inches irrigation

Watermark readings with connection problems at the 18 inch depth on the Control

Flo o d Blo ck A lm o n d s , Gyp s u m San d y L o am .

• 200
• 175
• 150
• 125
• 100
• 75
• 50
• 25

3/11 3/25 4/8 4/22 5/6 5/20 6/3 6/17 7/1 7/15 7/29 8/12 8/26 9/9 9/23 10/7 10/21 11/4 11/18

Soil Moisture Tension (cb)

18" 36" 60" Flo o d Blo ck A lm o n d s , C o n tr o l San d y L o am .

• 200
• 175
• 150
• 125
• 100
• 75
• 50
• 25

3/11 3/25 4/8 4/22 5/6 5/20 6/3 6/17 7/1 7/15 7/29 8/12 8/26 9/9 9/23 10/7 10/21 11/4 11/18

Soil Moisture Tension (cb)

18" 36" 60"

So maybe I should just use the pressure “bomb” to schedule my irrigations?

y = 7.8973x

3 - 19.142x 2 + 15.322x - 4.7723

R

2 = 0.8234

y = 4.5485x

3 - 13.916x 2 + 14.051x - 5.2879

R

2 = 0.8212

• 2.0
• 1.8
• 1.6
• 1.4
• 1.2
• 1.0
• 0.8
• 0.6
• 0.4

20% 30% 40% 50% 60% 70% 80% 90% 100% 110% Average Available Water to 1.8m (%) Average Stem Water Potential (MPa) Drip Fanjet Drip (polynomial) Fanjet (polynomial)

Variation in tree specific SWP decline with declining soil moisture – doesn’t always match classic soil physics

y = 11.36x

3 - 33.036x 2 + 32.157x - 11.138

R

2 = 0.8369

• 2.2
• 2.0
• 1.8
• 1.6
• 1.4
• 1.2
• 1.0
• 0.8
• 0.6
• 0.4

40% 50% 60% 70% 80% 90% 100% 110% Available Water to 1.8 m for Fanjet Tree 190 (%) Tree Stem Water Potential (MPa) Soil Saturation Extract % (SP) 43% Average Rootzone ECe 3.90 dS/m

(a)

y = -14.775x

3 + 27.914x 2 - 13.734x - 0.1106

R

2 = 0.7518

• 2.2
• 2.0
• 1.8
• 1.6
• 1.4
• 1.2
• 1.0
• 0.8
• 0.6
• 0.4

40% 50% 60% 70% 80% 90% 100% 110% Available Water to 1.8 m for Fanjet Tree 207 (%) Tree Stem Water Potential (MPa) Soil Saturation Extract % (SP) 33% Average Rootzone ECe 2.21 dS/m

(b)

CONCLUSION (THE END): Seat of the pants still the most common “technology” used in the

• field. Most growers admit they need “sharper”

tools …

…but they need to see the proof that the new technology is effective, dependable and profitable -- not just another load of snake oil guano!

Technology is helpful, but it can never replace your shadow in the field.