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Advancements in Irrigation Technology and their Impact on Water Management
Spring 2017 Water Seminar Series Lincoln, NEMarch 15, 2017
Daran R. Rudnick, Ph.D.Assistant Professor: Irrigation Specialist
Department of Biological Systems EngineeringWest Central Research and Extension Center
University of Nebraska-LincolnPhone: (308) 696-6709, Email: [email protected]
Personal Background
• Hometown: South Sioux City, Nebraska
• Education:
• B.S. Biological Systems Engineering, UNL, 2011
• M.S. Agricultural and Biological Systems Engineering, UNL, 2013
• Ph.D. Agricultural and Biological Systems Engineering, UNL, 2015
• Appointment:
• Irrigation Management Specialist (50% Research/ 50% Extension)
HometownSouth Sioux City, NE
WCRECNorth Platte, NE
UNLLincoln, NE
Research Team• Turner Dorr: Irrigation Research
Technologist II
• Tsz Him Lo: PhD Graduate Research Assistant
• Jasreman Singh: MS Graduate Research Assistant
• Jacob Nickel: Irrigation Research Technician
• Bridgett Dorr: Program Assistant
Himmy Lo Jasreman Singh
Turner Dorr& Bridgett Dorr
AcknowledgementThis study is based upon work that was jointly supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture (USDA-NIFA) under award numbers 2016-68007-25066 and 2016-68008-25078, United States Geological Survey Section 104B under award number G16AP00068, and the Daugherty Water for Food Global Institute under award number 01117420. Also thankful for industry support through providing equipment and services.
Why do we Irrigate???
When precipitation and stored soil water in the crop root zone are insufficient to meet crop evapotranspiration (ET) demand, irrigation is required.
Insufficient Irrigation can reduce:• Total Biomass
• Grain Yield
• Grain Quality
• Net Return ($ per ha)
Excessive irrigation can result in:• Runoff
• Soil Erosion
• Deep Percolation of Water (and Nutrients)
• Environmental Degradation
• Anaerobic Soil Conditions (Yield Penalty)
• Increased Pumping Cost (i.e., energy cost)
Source: Irmak (2009), Rudnick and Irmak (2015)
Nebraska Precipitation
Precipitation, mm
100 - 200
200 - 250
250 - 300
300 - 350
350 - 400
400 - 450
450 - 500
500 - 550
550 - 650
> 650
2000 2005
2010 Lng-Term
Avg.
Precipitation Increases West to East Irrigation Increases East to West
Source: Rudnick et al. (2015)
Nebraska: Density of Registered Irrigation Wells
2007
Nebraska: Nitrate Groundwater Contamination
Recorded concentration of nitrate (NO3) in irrigation wells from 1974 to 2012 (Quality-Assessed Agrichemical Database for Nebraska Groundwater, 2013).
EPA Maximum Contamination Level (MCL) is 10 ppm
Effects of Over- or Under Irrigating
Impact of Water Stress
Full Irrigation Deficit Irrigation Rainfed
Source: Jeff Golus
Runoff and Soil ErosionSource: Pioneer.com
High Soil Water Content
Crop Water Requirements
Depends on:
• Crop Type & Variety
• Growth Stage
• Soil Water & Nutrient Availability
• Soil Physical & Chemical Properties
• Micrometeorological Conditions
• Among others
Corn crop water use or daily evapotranspiration (ET) from a well-watered crop. The smooth line (A) depicts long-term daily ET and the jagged line (B) depicts daily ET for an individual year. (Taken from UNL NebGuide G1850, http://extensionpublications.unl.edu/assets/pdf/g1850.pdf).
Corn Water Use (inch per day)
Water Demand from Various Sectors
Climate
Industry
Groundwater Declines in the Ogallala Aquifer
• Water level changes in the High Plains Aquifer, pre-development through 2007
• Groundwater is connected to surface water
• Reduction in groundwater levels can limit water available for irrigation
• Consequently, restrictions have been enforced in areas to sustain and/or extend the useable life of the aquifer for future generations
Source: McGuire (2009) as modified from Lowry et al. (1967); Luckey et al.
(1981); Gutentag et al. (1984); and Burbach (2007). Taken from Konikow (2013)
• Nebraska Natural Resource Districts (NRDs) water management regulations can include:
• Allocating groundwater
• Augmenting surface water
• Requiring flow meters
• Instituting well drilling moratoriums
• Requiring water use reports
• Restricting expansion of irrigated acres
Nebraska Natural Resource DistrictsAllocations Updated February 2014
• Upper Niobrara-White NRD
• 54” per 4 years
• North Platte NRD
• 70” per 5 years
• & Pumpkin Creek = 36” per 3 years
• South Platte NRD
• 42 to 54” per 3 years (by subarea)
• Upper Republican NRD
• 65” per 5 years
• Middle Republican NRD
• 60” per 5 years
• Twin Platte NRD
• No allocation
• Upper Loup NRD
• No allocation
• Middle Niobrara NRD
• No allocation
Conventional Sprinkler IrrigationApplying a uniform depth of water per area through the irrigation system to meet average crop water demands of a field.
Source: pintrest.com
Center Pivot (1960’s)
Irrigation Distribution Uniformity1.
2.4.
3.Source: ASAE (2003)
Source: Chuck Burr
Mobile Drip Irrigation (MDI)
System Types
• Sprinkler (Senninger IWob) & MDI
Irrigation Levels
• Full, Deficit, & Rainfed
Residue Levels
• No-Removal & Baling
MDI Research• Preliminary Results
• Similar grain yields and kernel weights across system types
• Future Research Efforts
• Crop Water Use (ET)
• Long-term trends in production & water use
Variable Rate IrrigationSystem Description
Variable Rate Irrigation (VRI)
Applying variable depths or rates of water through an irrigation system to meet differences in crop water demands, soil conditions, and/or other constraints.
0.60 – 0.90 m
0.30 – 0.60 m
0 – 0.30 m
Available Water Capacity, mm
Source: Rudnick and Irmak (2014a, 2014b)
Types of VRI
Depending on system and controller VRI can be managed in sectors, bank of sprinklers, or individual sprinklers.
Fixed Zone Control Irregular Zone ControlSector/Speed Control
Speed/Sector Control
• Changes end tower speed at specified angular positions
• Modifies application depth in sectors of the circular pass
• Alters application duration but not application intensity
• Does not affect sprinklers, system curve, or pump performance curve
Sector/Speed Control
15 mm 20 mm25 mmapplication
intensity
time
at a given radius
from pivot point
Sprinkler Control• Changes discharge of individual or banks of
sprinklers
• Relies on valves directly upstream from sprinkler
• Changes in sprinkler discharge achieved by pulsing
• Turns off a sprinkler for a fraction of a cycle
• Optimizes timing to minimize flow rate oscillations
• Modifies application depth in more flexibly shaped zones as compared to sector control
Solenoid Valve
Pressure Regulator
Sprinkler
Video of Pulsing Sprinklers
Sprinkler Control• Individual or groups of sprinklers (i.e.,
banks of sprinklers)
• Changes in application depth accommodated by• Speed of pivot
• Pulsing of sprinklers
• Management zone must be greater than sprinkler throw diameter (consider sprinkler overlap!). More zones = more work!
Fixed Zone Control
15 mm
20 mm
25 mmapplicationintensity
time
sprinklers at a given
radius from pivot point
Irregular Zone Control
Example: Fixed Zone Pivot at Big Springs, NE
Span 1 - 6: On
Span 7-8: Off
Primary Valve
Secondary ValvesSmallest Zone1ᵒ ChangeSpan Control
Controller
Example: Sprinkler Controlled Pivot at Grant, NE
Variable Frequency Drive (VFD)
• VFD speeds up or slows down the pump motor to reach a desired operating pressure or flow rate
• Adopting VFD will depend on flow rate & pressure changes within the system (is it economical?)
• High or premium efficiency motors are often required
Irrigation Management Technology Benefits & Challenges
Irrigation and N Fertilizer Management
A primary research and production goal is to further improve irrigation and nitrogen use efficiency to enhance economic return as well as prevent environmental degradation. Addressing the following will aid in this effort.
• Reduce uncertainty in measuring/estimating crop water and nitrogen requirements
• Account for spatial and temporal differences in crop water and nitrogen demand
• Accurately apply inputs to minimize losses• Irrigation: runoff, percolation, evaporation
• Nitrogen (depends on N type): volatilization, leaching, de-nitrification, runoff
• Concurrently manage irrigation and nitrogen fertilizer
• Fertigation is a step forward in this direction
Some Useful Information for Irrigation ManagementInformation (Source):
• Historical Records (Yield data, compaction issues, etc.)
• Soil Properties (NRCS soil surveys, ECa mapping)
• Topography (DEM-digital elevation maps via survey, LiDar, etc.)
• Field Conditions (Residue level, pest pressure, nutrient availability, etc.)
• Visual Observations (Drainage ways, streams, roads, etc.)
• Soil Water Status (Soil water sensors)
• Evaporative Demand (Climatic variables via weather station)
• Crop Water Stress (Thermal sensors)
• Crop Growth and Condition (Canopy reflectance, visual imagery, and crop models)
• Remote Access to System (Telemetry)
• System Performance (Pressure transducers, telemetry, etc.)
Management Zone Delineation
• Apparent Electrical Conductivity (ECa)• Easy to measure and relatively low cost
• Indirect indicator of important soil physical and chemical characteristics
• Commonly used for VRI application
• Some Factors Impacting ECa• Clay content and mineralogy
• Soil salinity
• Cation exchange capacity
• Soil pore size distribution
• Temperature
• Organic matter content
• Soil water content
Source: Rudnick and Irmak (2014)
ECa Response Curve vs. Rooting Depth
Source: Irmak and Rudnick, 2014
Crop Type Total RootingDepth (ft)
Effective RootingDepth (ft)
Alfalfa 8 – 12 4 – 5
Corn 5 – 6 3 – 4
Sorghum 6 – 7 3 – 4
Soybean 5 – 6 2 – 3
Winter Wheat 4 – 5 2 – 3
Mature Growth Stage, under well drained, deep silt loam soils
ECa vs. Soil Hydraulic Properties
Sources: Rudnick and Irmak (2014)
𝐴𝑊𝐻𝐶 = 𝐹𝐶 −𝑊𝑃 × 𝑅𝐷
AWHC: Available Water Holding Capacity
FC: Field Capacity
WP: Wilting Point
RD: Rooting Depth
Soil Type Available Water (in/ft)
Silt Loam 2.5
Sandy Clay Loam 2.0
Silty Clay Loam 2.0
Silty Clay 1.6
Sandy Loam 1.4
Loamy Sand 1.1
Fine Sand 1.0
Available Water
Diagram for Irrigation using Soil Water Sensors
Management Zone
Water Freely Drains
Crop Water Stress Zone
Water NotAvailable to the Crop
Dry Soil
Saturation
Field Capacity
MAD = Trigger PointLatest Start Date
Wilting Point
Irrigation
Soil WaterSensor
Some In-Situ Soil Water Sensor Companies
Soil Water Sensors & ETgage
Campbell Scientific CS616SWC
Campbell Scientific CS655SWC, Temp, & EC
MPS-2 or MPS-6 5TE EC-5
SWP & Temp SWC, Temp, & EC SWC
---------- Decagon Devices ----------
Stevens Hydra Probe IISWC, Temp, & EC
Acclima True TDRSWC, Temp, & EC
Irrometer WatermarkSWP
Irrometer TensiometerSWP
ETgage (Atmometer)Reference ET
Legend:SWP: Soil Water PotentialSWC: Soil Water ContentTemp: Soil TemperatureEC: Bulk Electrical Conductivity
In-Field Sensor Evaluation
Sensors:
• AquaSpy
• AquaCheck
• John Deere Field Connect
• Hortau
• Decagon 5TE, EC5, MPS-2, MPS-6
• Stevens Hydraprobe
• Acclima TDR315
• Campbell Scientific CS616 & CS655
• CPN Neutron Gauge
• Irrometer Watermark, Tensiometer
Year: 2016
Location: North Platte, NE
Crop Type: Soybean
Loam Soil little salinity
In-Field Sensor Performance
• All Sensors tended to over-estimate
θv (m3 m-3) Combined Depths
Sensor MD SDD RMSD
TDR315 0.047 0.019 0.050
CS655 0.056 0.055 0.078
HydraProbe2 0.095 0.036 0.102
5TE 0.036 0.015 0.039
EC5 0.048 0.026 0.054
CS616 0.149 0.051 0.157
Field Connect* 0.079 0.027 0.083
AquaCheck* 0.162 0.017 0.163
Evaluation of Calibration Techniques
• Offset Calibration
• 2 Point Calibration
• Regression Fitting
• Retention Fitting
• Laboratory Calibration
Offset Example:• Take one accurate
measurement in-season
• Offset all other points
• Assumption: Regression response is linear with a slope of 1
Well-Performing Offset Calibration
In-Field Regression Calibrations
Regression Response
• 5 Linear and 19 Quadratic
Linear Responses
• Estimate of intercept > zero
• Linear Coefficient < one
• Sensors are more sensitive than reference
Quadratic Responses
• Sensitivity generally increased with θv within the observed θv
range
Laboratory Calibrations
• Most sensors tended to over-estimate θv in the lower observed θv
range.
• Variability in sensor performance was observed between lab and field calibrations.
Laboratory Calibration Techniques
Repacked versus Intact Soil Cores
• Different drying trends
• Repacked slightly underestimated water content
Statewide Soil Experiment
• Five Soil Types
• Four Salinity Levels
• Two Sensors Evaluated• TDR 315 & CS655
weight % of soil solids
weight % of mineral fraction g cm-3
SoilOrganic Matter
Sand Silt ClayTarget Bulk
Density
V 0.2 (0.0) 88 (1) 7 (1) 5 (1) 1.6
C 2.1 (0.1) 55 (3) 23 (3) 22 (0) 1.3
K 2.6 (0.1) 35 (2) 35 (3) 30 (2) 1.3
H 2.4 (0.1) 14 (3) 40 (5) 46 (2) 1.4
W 2.5 (0.1) 8 (4) 42 (1) 49 (4) 1.4
Instrumentation for VRI Research
Research Questions
• How to collect and analyze different information of various spatiotemporal resolutions to inform VRI scheduling and prescription generation?
• Would VRI affect nitrogen management? If so, how can irrigation and nitrogen management be optimized simultaneously?
Year 1 Management Zones and Treatments
• Two management zones—one consisting of gravelly soils and another consisting of non-gravelly soils
• Zones were delineated using ECa, assuming lower ECa represents gravelly soils
• Full irrigation (F): attempt to eliminate any water stress
• Conventional (C): uniform irrigation based on the non-gravelly soil
• Deficit irrigation (D): allow water stress during less sensitive growth stages
• Non-irrigated (R): no irrigation
Sprinkler Controlled Pivot at Brule, NE
Point-Based Water Status DataAquaCheckmultisensorcapacitance
probe
neutron moisture meter
wireless infrared
thermometer
scaled frequency
units
0
50
100
150
200
250
300
D F C R D F R
Tota
l Wat
er
in 0
-0.9
m
June 23rd, 2016
0-0.3 m
0.3-0.6 m
0.6-0.9 m
non-gravellygravelly
irrigation:
soil:
0
50
100
150
200
250
300
D F C R D F R
Tota
l Wat
er
in 0
-0.9
m
October 3rd, 2016
0-0.3 m
0.3-0.6 m
0.6-0.9 m
non-gravellygravelly
irrigation:
soil:
0
5
10
15
20
25
30
35
0:00 8:00 16:00 0:00 8:00 16:00 0:00
Surf
ace
Te
mp
era
ture
(°C
)
Time
fully irrigated
deficit irrigated
Visible Imaging
deficit irrigatedfully
irrigated
deficit irrigatedfully
irrigated
August 1st, 2016 (silking) September 26th, 2016 (30% milk line)
Thermal Infrared Imaging aerial image taken by AirScoutground-based images taken using FLIR E60
non-irrigated
fully irrigated
Radiometric Temperature
Instruments• Infrared Thermometers (IRTs)
• Aerial Thermal Imagery (Airscout)
Observations
• Airscout observed smaller ranges in Temp as well as lower Temp values.
AirScout thermal (left) and visible (right) image of the Brule site on 9/26/2016; the 12 monitoring locations are marked and labeled, and the rainbow color scale from blue to
red in the thermal image denotes radiometric temperatures from low to high.
Collaborative VRI Research
• Irrigation Management using Remote Sensing
• Research project initiated at UNL Brule Water Laboratory in 2016
• Collaboration:• Burdette Barker
• PhD Graduate Student
• UNL Biological Systems Engineering
• Derek Heeren• Assistant Professor: Irrigation Engineer
• UNL Biological Systems Engineering
• Christopher Neale• Director of Research
• Water for Food Daugherty Global Institute
WCREC Research Site: Brule, NE
Elevation (m)
Topographic Map
University of Nebraska-LincolnWest Central Research and Extension Center
Brule Water Laboratory near Brule, NE
0 - 2
2 - 4
4 - 6
6 - 8
8 - 10
10 - 12
Slope (%)Soft Edge
1073 - 1075
1070 - 1073
1067 - 1070
1064 - 1067
1061 - 1064
1058 - 1061
1055 - 1058
1052 - 1055
1050 - 1052
±
Irrigation Management Using Remote Sensing
Multispectral Imagery (Spatial –Low Temporal)
Soils Map
Weather Data (High Temporal)
Previous Irrigation Maps
New Irrigation Prescription and Schedule
RS – Based Hybrid Water
Balance Model
Neale, C.M.U., Geli, H.M.E., Kustas, W.P., Alfieri, J.G., Gowda, P.H., Evett, S.R., Prueger, J.H., Hipps, L.E., Dulaney, W.P., Chavez, J.L., French, A.N., and Howell, T.A. (2012). Soil water content estimation using a remote sensing based hybrid evapotranspiration modeling approach. Advances in Water Resources, 50, 152-161.
VRI System at Research Center
Experimental Layout at WCREC
• Treatments
• RS-based VRI management
• Conventional or “uniform” management using water balance
• Blocked by available water capacity zones (determined from neutron probe and soil series)
• Continuous maize crop ~49 ha
• Individual sprinkler zone control VRI Aerial Image Source: USDA-FSA (2014). USDA-FSA-APFO NAIP MrSID
Mosaic for Keith County, Nebraska. U.S. Department of Agriculture, Aerial Photography Field Office, National Agricultural Imagery Program.
Preliminary Results WCRECIrrigation Depth:• Conventional: 324 mm
• VRI w/ Remote Sensing: 342 mm
Variability in seasonal irrigation amount.
Fertigation ResearchDemonstrate the potential for improving nitrogen use efficiency (NUE) while optimizing profitability through the use of canopy reflectance and crop N modeling techniques.
• Collaboration:• Brian Krienke
• Suat Irmak
• Richard Ferguson
• Tim Shaver
• Charles Shapiro
• Keith Glewen
• Locations:• West Central Research and Extension Center, North Platte, NE, USA
• South Central Agricultural Laboratory, Clay Center, NE, USA
Variable Rate Fertigation (VRF)
Applying variable amounts or rates of fertilizer through an irrigation distribution system to meet spatial and temporal differences in crop nutrient demands, soil conditions, and/or other constraints.
VRF Scenarios:
• VRF with variable rate fertigation pump• Uniform Irrigation and Variable Fertilizer
• Variable Irrigation and Uniform Fertilizer
• VRF with constant rate fertigation pump• Use VRI technology with uniform fertilizer speed
Thank You!
The mention of trade names or commercial products in and during this presentation does not constitute an endorsement or recommendation for use by the University of Nebraska-Lincoln or the author.