Soil Moisture Soil Moisture Management with Management with

Watermark SensorsWatermark Sensors

Kevin HeatonKevin HeatonUtah State University ExtensionUtah State University ExtensionUtah State University ExtensionUtah State University ExtensionKane and Garfield County AgentKane and Garfield County Agent

February 6February 6--7 20077 2007February 6February 6 7, 20077, 2007

IntroductionIntroductionGrant Funding Obtained Through the EPA Targeted Watershed Program

Irrigation Efficiency Real time ET—Crop Water Use

g g

Crop Water Use

Water Quality

Soil Moisture Monitoring

On Farm Soil Moisture MonitoringOn Farm Soil Moisture MonitoringOn Farm Soil Moisture MonitoringOn Farm Soil Moisture Monitoring

20 Participation Farms20 Participation Farms20 Participation Farms20 Participation Farms2 field locations/farm2 field locations/farm3 sensors at each location 1’ 2’ & 4’3 sensors at each location 1’ 2’ & 4’3 sensors at each location, 1 , 2 , & 43 sensors at each location, 1 , 2 , & 4

Installed 5 data Installed 5 data loggersloggersHopefully, we’ll Hopefully, we’ll p yp yanswer the question, answer the question, “Is it time to irrigate?”“Is it time to irrigate?”Is it time to irrigate?Is it time to irrigate?

EquipmentEquipmentEquipmentEquipment

Irrometer CompanyIrrometer CompanyIrrometer CompanyIrrometer Company951951--689689--1701 Phone1701 Phone951951 689689 3706 Fax3706 Fax951951--689689--3706 Fax3706 FaxP.O Box 2424 Riverside, CA 92516P.O Box 2424 Riverside, CA 92516sales@irrometer comsales@irrometer comsales@irrometer.comsales@irrometer.comtechsupport@irrometer.comtechsupport@irrometer.comWatermark Soil Moisture Sensors, Meters Watermark Soil Moisture Sensors, Meters and Data Loggers.and Data Loggers.

InstallationInstallationInstallationInstallation

Soak sensors over nightSoak sensors over nightSoak sensors over nightSoak sensors over nightIf time permits, conduct wetting and drying If time permits, conduct wetting and drying periodsperiodsperiodsperiods

Determine root zone of crop install Determine root zone of crop install sensors accordinglysensors accordinglysensors accordinglysensors accordinglyMake hole at least 7/8” in DiameterMake hole at least 7/8” in DiameterCritical to have good soil to sensor contactCritical to have good soil to sensor contact

Placement in the FieldPlacement in the FieldPlacement in the FieldPlacement in the Field

AccessibilityAccessibilityAccessibilityAccessibilityInstall in representative areasInstall in representative areasA id tA id tAvoid extremesAvoid extremesi.e. Floodi.e. Flood

2/3 way down run (usually the lowest water 2/3 way down run (usually the lowest water penetration)penetration)

PivotPivotEvery 10Every 10--15 acres15 acresyy

Reading SensorsReading SensorsReading SensorsReading Sensors

Twice each weekTwice each weekTwice each weekTwice each weekMore often, the prettier graphMore often, the prettier graphF t i tF t i tFor management purposes, prior to For management purposes, prior to irrigation and after irrigationirrigation and after irrigationMeters read resistanceMeters read resistance

Resistance is converted to Centibars Resistance is converted to Centibars Measures the force/area required to remove water Measures the force/area required to remove water from the soilfrom the soil

Soil Water Holding CapacitySoil Water Holding CapacityField Capacity, Available Water and

Permanent Wilting Point 10 30g

3 54

4.5

Field 1500

10-30 Cntbars

2.53

3.5

es/f

oot

Available

Available Water

Capacity 1500 Cntbars

11.5

2

Inch

e AvailableWaterWiltingPointUnavailable

Wilting Point

00.5

Sand Sandy Loam Silt Clay Clay

Unavailable Water

Sand SandyLoam

Loam SiltLoam

ClayLoam

Clay

Soil TypeSource: “Water”, The Yearbook of Agriculture, USDA 1955, page 120.

Recommended Values at Which to Recommended Values at Which to I i F CI i F CIrrigate Forage CropsIrrigate Forage Crops

Soil TypeSoil Type Moisture ReadingMoisture ReadingSoil TypeSoil Type Moisture Reading Moisture Reading (centibars)(centibars)

Sand*Sand* 4040 5050SandSand 4040--5050

Sandy LoamSandy Loam 5050--7070yy

LoamLoam 6060--9090

Clay Loam or ClayClay Loam or Clay 9090--120120

*Caution: Soil moisture sensors may not respond quickly enough to indicate the rapid decline of soil moisture in very sandy soils.

Over IrrigationOver Irrigation

Over IrrigationOver Irrigation

Over IrrigationOver Irrigation

Pretty Good SchedulingPretty Good Scheduling

Under IrrigationUnder IrrigationUnder IrrigationUnder Irrigation

What in the “Sam Heck”What in the “Sam Heck”is going on here?is going on here?

Soil Moisture SummarySoil Moisture SummarySoil Moisture SummarySoil Moisture Summary

13% Under irrigated13% Under irrigated13% Under irrigated13% Under irrigated16% Well timed irrigation16% Well timed irrigation71% O I i ti71% O I i ti71% Over Irrigation71% Over IrrigationRecommendations:Recommendations:

The degree of over irrigation is not yet The degree of over irrigation is not yet understoodunderstoodTake into account environmental and Take into account environmental and economic factors before changing schedulingeconomic factors before changing scheduling

Potential ImpactsPotential ImpactsPotential ImpactsPotential Impacts

ChangeChangeChange Change irrigation irrigation managementmanagement IrrigationSoilmanagement management

Improve Improve IrrigationEfficiency

Soil Moisture

ppconservation conservation

ReduceReduceReduce Reduce pollutionpollution

Crop Water Use

Questions???Questions???Questions???Questions???