On-farm Response Strategies to Drought

Inland NW Drought Forum 2013

Boise, ID Water Center

Oct 18, 2013

Howard Neibling, P.E.

Extension Water Management Engineer, University of Idaho

Response depends on:

• Water source (surface or well)

• Timing and amount of reduced water delivery

• Cropping mix that can be grown

• Irrigation systems used

• Soil depth and water holding capacity

Water Source Considerations

• Wells – Timing and amount of water supply is under

farmer control within water right or other constraints

– If total withdrawal is limited, farmer can still manage timing of reduced well flow

• Surface – Timing and amount depend on water delivery

policies and system constraints – less flexibility than with wells

3/30

4/13

4/27

5/11

5/25 6/

86/

22 7/6

7/20 8/

38/

178/

319/

149/

28

10/1

2

10/2

6

Date

Winter Grain

Spring Grain

Dry Beans

Potatoes

Field Corn

Sugar Beets

Alfalfa

Tillering

Tillering

Boot - flower

Boot - flower

Flowering

Tuber set

Pollination

Germination, Emergence

& Early Growth

Early growth New fall seedings

Timing of Crop ET and Critical Crop Stages

for Magic Valley Conditions

Timing and amount of delivery

• If limited supply can be delivered for full season at reduced rate – All crops can be grown but on limited area – Sprinkler systems can be modified to cover less area with

reduced flow – then crop stress on reduced areas can still be minimized

• If limited supply must be delivered at nearly full flow until supply is gone (e.g. leaky canals) – Only shorter-season crops can be grown – Carefully schedule system turn-on (wait till water needed) – Fill deep soils early to minimize evaporation losses and

store maximum water in crop root zone

Adjust cropping mix to fit water supply

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

Seas

on

al E

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allo

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acre

30-yr Average Estimated Seasonal ET, Kimberly

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

3/31 4/14 4/28 5/12 5/26 6/9 6/23 7/7 7/21 8/4 8/18 9/1 9/15 9/29 10/13

Ag

rim

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Esti

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rop

ET, in

/d

Average 30 Year Calculated ET for Typical Magic Valley Crops

Alfalfa Mean Corn Russet Potatoes Spring Grain Lawn

Irrigation system considerations

• Surface Irrigation: less water means more attention to set time and flow rates

• Sprinkler systems:

– Set or set-move systems are usually designed to be able to “keep up” all season. With reduced water

• Fix leaks (average 12% losses)and replace worn nozzles (average 13% over application)

• Use shorter set times to avoid over-watering

• Skip sets with lowest crop productivity

0

1

2

3

4

5

6

7

8

0 5 10 15 20 25 30 35

No

zzle

flo

w, g

pm

Nozzle number

WL15 wheel line: 9/64 nozzle, 32 psi

actual flow no-wear flow

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

0 5 10 15 20 25 30 35

No

zzle

flo

w, g

pm

Nozzle number

2-month old R2000 windfighter

actual flow no-wear flow

CU=78%

CU=61%

CU=56%

Center pivot systems

• Usually designed to apply less than peak ET

• Application per revolution limited to prevent runoff

• Therefore, apply extra water before peak ET period

• When water delivery rate is reduced – If system is over 5 years old, replace sprinkler package (poor

measured water application uniformity meant 65% of systems tested needed new sprinkler packages)

– Shut off end gun and re-nozzle

– Shut off end gun and outer span if necessary (outer span most prone to runoff)

– Run system as slow as possible without runoff to minimize evaporation losses

– Plant half to early crop and half to later crop / re-nozzle for 2nd crop

Use irrigation scheduling to best match water applied to crop need during the

growing season

• Water budget with AgriMet

• Shovel or soil probe with soil feel and appearance method

• Soil sensors with in-field data loggers

• Soil sensors with data transmitted to web server and accessible from internet

Hansen AM 400 Data Logger and atermark sensors

• Cost: about $3 5-$ 00 for, ·ire and 6 sensors

• Records data from 6 sensors every 8 hours

• Singe button disp a· sho vs 5 veeks data for each senso

• \ eatherproof and can be used in the winter

• _ 1emory stores entire season of data • ;vithout do oading • Can do \• oad at any time • Shows change in moisture, ·th

time at se ected depths • Can be set up to sho · eaching

events

Sensor source: http: · ~ :..irrometer.com!sensors.html

Data ogger source:

http:'. . ·.mkhansencom'

Unive~sity of Idaho Extension

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Decagon ECH O Probe Data Logger

• Capacitance pr be (me-asure-S dielectri~ permitth'ity)

soil

• Output in· lumetric ater c ntent

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Datalogger ab supports rain gag"' & temp sensors

ufr ctured by Decag n (Pullman, ·A)

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Data from 1 or 2 probes with soil moisture measurements at 4,8,12,18,24 and 40” transmitted to JD website for user access from any web-connectable computer.

Approximate cost for components for one field:

Gateway logger / transmitter with first year installation and data plan : $$2900

1-m probe with capacitance-type sensors and 200 ft cable to connect to Gateway: $1900

Source: local John Deere dealer

Em, i IJ'o SCA I Flat Cap Probe

F eatnu es i rtdlud e:

~ N l!l l!iiple sensors willil flexib e deplh pfaceme,nt (at W cm in crem ents) 4 Mo nitoiring ifrorn s I all 0111 deiplhs (® - 1l!D Clill ) to deep ilils la rna1l ions (> 40 metres ~ Le nglh of prnbe icusto: is,ed to st.11 it 1he app:lic,ai i 011 (p:ro be lengii h acljustab e in Ute fiel d) 4 Up to 16 selilsors on olile prob e (rnm:islure. orr moislurelsa linlty) ~ llil-b'U iH p:ro be mien tali olil and d eplh settingis, i o enha rtce selilso:r re peatabili ly 4 Fu[I servi:ce abmty. ~ Flexible con rteclivifly. for wide· rnn; ,e of d ata relri ev al opli on:s

Pro be Sea~li n g

The bottom o' the acc ess 1ube is typically sea led using a d oub e~rin; ,ed expandab~e rulb1ber bung , p:ror1{ cl irtg 2 sealing1 paints and preventing1 undlergrmmd mo·s,tnu e f ro m en1ering the t L11be . A slunry. cap~ also a,11ia'ilable.

The 1op of the a,ccess ru be is seated w ith 2 d iffelienl: top cap des ·gns, depe , din; on appU:cat ion .

Envi roSCA N Screw Cap,

•· Top cap p mi rrudes above the so ii s u IJ'f ace •· E asy to n111d and lie ad ilfy accessibl e· •· T~g1htuy.· sea ed vJlh a rnlb1ber 0-IJ'ing •· Sim pl'y u n-screi.vs, g ivirtg eas:y. access l:o 1he probe Jo:r serv.rcirtg

EnviroSCA N F m: Cap

•· A.llows ' or the probe· io sit · 'us h wilh the g rnund s,mface •· W arl:er-i "ght 3 p oin1 sea lirtg design •· PriCMdes re·adv access to lihe p rob e foll' sel!Viciing •· Avo:itlils p oleni i'all y.· oost l')" damage fi"o:n madhinery·

EnviroSCA N Screw Cap Pr1obe

Unive~sityotldaho Extension

Analyze your data through graphica l display

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Unive~sityotldaho Extension

Summary: on-farm irrigation responses

• Adjust cropping mix to match timing and rate of water delivery

• Perform needed irrigation system maintenance – Set & set-move systems: fix leaks, replace worn

nozzles, replace worn or malfunctioning sprinkler heads

– Center pivot /linear: replace pressure regulators & sprinkler packages older than 4-5 years

• Use an irrigation scheduling method to match water applied to crop need throughout the season

The End -- Questions?