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Irrigation Management Irrigation Management and Technologiesand Technologies

Freddie Lamm Freddie Lamm KSU Northwest Research Extension Center, Colby, KansasKSU Northwest Research Extension Center, Colby, Kansas

Norm KlockeNorm KlockeKSU Northwest Research Extension Center, Garden City, KansasKSU Northwest Research Extension Center, Garden City, Kansas

Danny RogersDanny RogersKSU Department of Biological and Agricultural Engineering, Manhattan, KansasKSU Department of Biological and Agricultural Engineering, Manhattan, Kansas

Many state, regional, and national collaborators, but to name a Many state, regional, and national collaborators, but to name a very important fewvery important few from K-State, from K-State,

Mahbub Alam, Ag Engr., Loyd Stone, Soil Physicist, Alan Schlegel, Soil Scientist, Mahbub Alam, Ag Engr., Loyd Stone, Soil Physicist, Alan Schlegel, Soil Scientist, Troy Dumler, Bill Golden, and Dan O’Brien, Ag Economists. Troy Dumler, Bill Golden, and Dan O’Brien, Ag Economists.

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Wise and responsible water use requires both Wise and responsible water use requires both good management and good technologiesgood management and good technologies

Management and technology go hand-in-hand and both Management and technology go hand-in-hand and both can only be optimizedcan only be optimized in the presence of the other. in the presence of the other.

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Center pivot Center pivot sprinklers are the sprinklers are the predominant predominant irrigation system irrigation system in Kansas.in Kansas.

Although this technology is over 60 years old, we still find many Although this technology is over 60 years old, we still find many operational, maintenance, and/or uniformity problems. The popular operational, maintenance, and/or uniformity problems. The popular in-canopy drop nozzles have been oversold and are often misapplied.in-canopy drop nozzles have been oversold and are often misapplied.

Poor uniformity

Drop nozzles

K-State is assessing K-State is assessing these problems and these problems and helping producers helping producers and industry improve and industry improve sprinkler system sprinkler system performance. performance.

CP Testing

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Variable rate irrigation (VRI), also Variable rate irrigation (VRI), also known as Site Specific Irrigation known as Site Specific Irrigation (SSI) is an emerging center pivot (SSI) is an emerging center pivot sprinkler technology that may have sprinkler technology that may have some merit in Kansas. some merit in Kansas.

A commercial push on this A commercial push on this technology is likely to occur in the technology is likely to occur in the coming years. However, there coming years. However, there remains a strong need for remains a strong need for management strategies to be management strategies to be developed, as well as sound developed, as well as sound guidelines as to where this guidelines as to where this technology can really improve technology can really improve irrigation management in Kansas. irrigation management in Kansas.

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Subsurface drip irrigation (SDI) Subsurface drip irrigation (SDI) applies water below the soil surface to applies water below the soil surface to the crop root zone with small the crop root zone with small emission points (emitters) that are in a emission points (emitters) that are in a series of plastic lines typically spaced series of plastic lines typically spaced between alternate pairs of crop rows. between alternate pairs of crop rows.

SDI can be used for small, frequent, just-in-time SDI can be used for small, frequent, just-in-time irrigation applications directly to crop root system.irrigation applications directly to crop root system.

The primary ways that SDI could increase crop The primary ways that SDI could increase crop water productivity (WP), water productivity (WP), More crop per drop More crop per drop are: are:

Reduction and/or elimination of deep drainage, Reduction and/or elimination of deep drainage, irrigation runoff, and soil water evaporationirrigation runoff, and soil water evaporation

Improved infiltration, storage, and use of Improved infiltration, storage, and use of precipitation precipitation

Improved in-field uniformity and targeting of Improved in-field uniformity and targeting of plant root zone plant root zone

Improved crop health, growth, yield, and qualityImproved crop health, growth, yield, and quality

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Does SDI really increase Does SDI really increase crop per drop?crop per drop?There is growing evidence from There is growing evidence from our studies and others in the our studies and others in the Great Plains that SDI can Great Plains that SDI can stabilize yields at a greater level stabilize yields at a greater level than alternative irrigation than alternative irrigation systems when deficit irrigated. systems when deficit irrigated.

0.00 0.05 0.10 0.15 0.20 0.25Irrigation capacity (inches/day)

75

100

125

150

175

200

225

250

275

Co

rn y

ield

(b

u/a

cre)

KSU-NWRECColby, Kansas

Incanopy sprinkler, 1996-1999 (Wet years)Incanopy sprinkler, 2000-2001 (Dry years)Subsurface drip, 1996-1999 (Wet years)Subsurface drip, 2000-2001 (Dry years)

Can we make SDI pay?Can we make SDI pay?Yes we can! Yes we Yes we can! Yes we can!can!

We have developed a We have developed a spreadsheet template spreadsheet template for you to check using for you to check using your own economics.your own economics.

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0 1 2 3 4 5 6 7Irrigation Capacity (gpm/acre)

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Rel

ativ

e C

rop

Yie

ld

CornSoybeanGrain SorghumSunflower

Simulated crop yields at Colby, Kansas, 1972-2010.1 inch irrigation events95% application efficiency

Crop yields vary greatly with the declining well Crop yields vary greatly with the declining well capacities that irrigators are experiencing.capacities that irrigators are experiencing.

Irrigators cope by:Irrigators cope by:

•Crop selectionCrop selection

•Planting portion of Planting portion of field to alternative field to alternative cropcrop

•Reducing irrigated Reducing irrigated areaarea

•Adopting deficit Adopting deficit irrigation strategies irrigation strategies

•Combinations of the Combinations of the above.above.

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Value of Crop Residue Value of Crop Residue for Reducing Soil Water Evaporation (E) for Reducing Soil Water Evaporation (E)

under Sprinkler Irrigationunder Sprinkler Irrigation

Mini-lysimeters in irrigated cornCrop residue payback when overirrigatingCrop residue payback when overirrigating

None!None!

Crop residue payback under full irrigationCrop residue payback under full irrigation2.6 inches x $5/ac-inch x 130 ac = $1,6902.6 inches x $5/ac-inch x 130 ac = $1,690

Crop residue payback under limited irrigationCrop residue payback under limited irrigation3.7 in x 14 bu/ac-in x $5/bu x 130 ac = $33,6703.7 in x 14 bu/ac-in x $5/bu x 130 ac = $33,670

Irrigation and Percent Cover

E Losses

Savings Compared to

Bare Soil

Full irrigation, 75% residue cover 4.9 in. 35%

Limited irrigation, 75% residue cover 3.8 in. 49%

Reduction in pumping costsReduction in pumping costs

Increased crop revenuesIncreased crop revenues

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Variability in Winter, Growing Season, & Cropping Variability in Winter, Growing Season, & Cropping Season Precipitation (12 month) for Garden City, Kan. Season Precipitation (12 month) for Garden City, Kan.

(2005-2009)(2005-2009)

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Variability in Relative Corn Yield with IrrigationGarden City 2005-2009

Crop yields vary greatly with irrigation and with weather Crop yields vary greatly with irrigation and with weather conditions, and not only with in-season precipitation, but also conditions, and not only with in-season precipitation, but also with amounts received during the prior overwinter period.with amounts received during the prior overwinter period.

Since, Since, yield yield variability variability increases with increases with decreases in decreases in irrigation, irrigation, there is more there is more income risk.income risk.

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In a current federally-funded study In a current federally-funded study (with help from Governor (with help from Governor Brownback while still a Senator), Brownback while still a Senator), we are assessing the residual we are assessing the residual soil water levels after harvest, before planting, and the soil water levels after harvest, before planting, and the overwinter soil water gain in 90 irrigated and dryland fields overwinter soil water gain in 90 irrigated and dryland fields across 9 counties in western Kansas. across 9 counties in western Kansas.

Our results thus Our results thus far are showing far are showing a great amount a great amount of variability by of variability by location and location and producer.producer.

One of the easiest and most effective ways for a farmer to reduce overpumping is to account for soil water availability.

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A reduction in seasonal irrigation for A reduction in seasonal irrigation for continuous crop corn continuous crop corn will increasewill increase both the amount of overwinter soil both the amount of overwinter soil water gain and the soil water use by water gain and the soil water use by the next corn crop.the next corn crop.

Irrigation Irrigation (inches)(inches)

Over-WinterOver-WinterSoil Water Gain Soil Water Gain

(inches)(inches)

Next SeasonNext SeasonSoil Water Use Soil Water Use

(inches)(inches)

1212 3.33.3 1.81.8

88 4.94.9 3.23.2

66 5.95.9 2.92.9

33 6.06.0 4.34.3

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Development of Irrigation Management Decision Tools Development of Irrigation Management Decision Tools and Providing the Training Required to Use the Programsand Providing the Training Required to Use the Programs

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KanSched 2 is a second generation, user friendly, KanSched 2 is a second generation, user friendly, popular software program developed by K-State to popular software program developed by K-State to allow irrigators to schedule their day-to-day allow irrigators to schedule their day-to-day irrigation for multiple fields and crops using ET-irrigation for multiple fields and crops using ET-based water budgeting principles. based water budgeting principles.

Governmental Governmental cost-share cost-share programs are programs are available to available to irrigators that irrigators that adopt KanSched 2 adopt KanSched 2 for use on their for use on their farms.farms.

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KanSched 2 provides a visual record throughout KanSched 2 provides a visual record throughout the crop season for irrigators to track soil water the crop season for irrigators to track soil water content, irrigation, and rainfall amounts. content, irrigation, and rainfall amounts.

There is the There is the implicit implicit assumption assumption that that ALLALL wise wise and and responsible responsible irrigation irrigation must startmust start with with science-based, science-based, day-to-day day-to-day irrigation irrigation scheduling, scheduling, such as such as KanSched 2 !! KanSched 2 !!

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Find best crop combinations to utilize limited Find best crop combinations to utilize limited irrigation.irrigation.

Find best allocation of irrigation over chosen crops.Find best allocation of irrigation over chosen crops.

Find economic returns for all combinations of crops Find economic returns for all combinations of crops and irrigation.and irrigation.

Choose crop/irrigation combination: Choose crop/irrigation combination:

For best economic return; For best economic return;

Compatible with crop management systems;Compatible with crop management systems;

For acceptable income risk.For acceptable income risk.

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CWA Input Screen CWA Input Screen

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If you divide your field into 2 halves If you divide your field into 2 halves and want to grow corn and sorghum,and want to grow corn and sorghum,how should you allocate your water?how should you allocate your water?

OptionOption CropsCrops Irrigation (in)Irrigation (in) Net ReturnNet Return

11 Corn-SorghumCorn-Sorghum 12 and None12 and None $138$13822 Corn-SorghumCorn-Sorghum 9.6 and 2.49.6 and 2.4 $127$12733 CornCorn 6 on corn6 on corn $ 95$ 95

Annual Irrigation = 6 inches for total field areasAnnual Irrigation = 6 inches for total field areasAnnual Precipitation = 16 inchesAnnual Precipitation = 16 inches

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Forecasting Irrigation Schedule Forecasting Irrigation Schedule for Limited Irrigationfor Limited IrrigationBy Economic ReturnBy Economic Return

Pre-Growing Season Irrigation?Pre-Growing Season Irrigation?

Date of First Irrigation During the Growing Season?Date of First Irrigation During the Growing Season?

Irrigation Frequency?Irrigation Frequency?Irrigation System CapacityIrrigation System CapacityMandated Annual IrrigationMandated Annual Irrigation

Date of Last Irrigation During the Growing Season? Date of Last Irrigation During the Growing Season?

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Prior Harvest Prior Harvest Soil Water (%)Soil Water (%)

Yield Yield (bu/a) (bu/a)

Net Return Net Return (S/acre)(S/acre)

Winter Evaporation and Winter Evaporation and Drainage Losses (inches) Drainage Losses (inches)

3030 161161 358358 5.25.25050 177177 408408 5.85.87070 183183 431431 8.58.5

CYP Results for Irrigated Continuous Corn with CYP Results for Irrigated Continuous Corn with Different Amounts of Soil Water Following the Different Amounts of Soil Water Following the Previous Harvest when Cropping Season Irrigation Previous Harvest when Cropping Season Irrigation is 12 inches and Annual Precipitation is 16 inches. is 12 inches and Annual Precipitation is 16 inches.

The soil water content at the end of the growing The soil water content at the end of the growing season strongly affects the results of the next season strongly affects the results of the next growing season !!growing season !!

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Living with Limited IrrigationLiving with Limited Irrigation Consider Soil Water Evaporation/Crop ResiduesConsider Soil Water Evaporation/Crop Residues

Measure soil water Measure soil water Pre-season and during seasonPre-season and during season

Precipitation/Irrigation ManagementPrecipitation/Irrigation Management

Evaluate Yield Risk with Precipitation Variability,Evaluate Yield Risk with Precipitation Variability,

e.g., Crop Yield Predictore.g., Crop Yield Predictor

Choose crops that match the available amount of Choose crops that match the available amount of

water, e.g., Crop Water Allocator water, e.g., Crop Water Allocator

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It cannot be overemphasized that It cannot be overemphasized that manmanagement and technology go agement and technology go

hand-in-hand hand-in-hand

and both and both can only be optimizedcan only be optimized in the presence of the other. in the presence of the other.

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List of List of K-State Research and ExtensionK-State Research and ExtensionIrrigation-Related Websites:Irrigation-Related Websites:Mobile Irrigation LabMobile Irrigation Labhttp://mobileirrigationlab.com/http://mobileirrigationlab.com/

General Irrigation Topics at K-StateGeneral Irrigation Topics at K-Statehttp://www.ksre.ksu.edu/irrigate/http://www.ksre.ksu.edu/irrigate/

SDI in the Great PlainsSDI in the Great Plainshttp://www.ksre.ksu.edu/sdi/http://www.ksre.ksu.edu/sdi/

The next Central Plains Irrigation Conference will The next Central Plains Irrigation Conference will be held in Colby, Kansas, February 21-22, 2012.be held in Colby, Kansas, February 21-22, 2012.

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Some Key Some Key Kansas Kansas

Irrigation Irrigation TrendsTrends

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Corn is by far the primary irrigated crop in KansasCorn is by far the primary irrigated crop in Kansas

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y = -0.0156x + 1.3265

y = -0.0436x + 4.0361

0.000.250.500.751.001.251.501.752.002.252.502.753.003.253.503.754.004.254.504.755.00

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Year

Total Irrigation Water and Average Acre-foot per Acre of Water Pumped in Kansas by Year

AC-FT per Acre Million of AC-FT Pumped

There is a trend towards less reported irrigation pumping.There is a trend towards less reported irrigation pumping.

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Irrigated yields are increasing 2.4 times faster Irrigated yields are increasing 2.4 times faster than dryland and have much less variability.than dryland and have much less variability.