Precision Irrigation

Presented by Xiaoxue LiPresented by Xiaoxue Li

Precision irrigation

DefinitionDefinition Also called site-specific irrigation A tool of precision farming that involves the

delivery of irrigation water in optimum amount over an entire field

New generation of innovative systems to monitor and control soil moisture deficiency and irrigation

Why PI?

Internal reasons Very few fields are uniform, the need for

irrigation may differ between different zones of a particular field

Most currently used irrigation systems apply water at constant rates, therefore some

areas of a field may receive too much water and other areas of a field may not receive enough

water

Why PI

Driving forces Excessive water application could contribute to

surface water runoff or leaching of nutrients and chemicals to groundwater

Precision irrigation systems would have the ability to apply water directly where it is needed, therefore saving water and preventing excessive water runoff and leaching

Systems having potential for PI

Center pivot and and the similar linear-move system have higher potential Provide an outstanding platform on which to

mount sensors for real time monitoring of plant and soil conditions

Interact with a control system for optimal environmental benefits

Systems having potential for PI

Drip irrigation system also offers precision irrigation technology However, drip irrigation represents only a small

share of total irrigation High costs limit this kind of equipment to

mainly higher-value crops like fruits and vegetables

Precision irrigation scheduling

Irrigation scheduling is the heart of precision irrigation, which simply knows where, when to irrigate and how much irrigation water to apply

An effective irrigation schedule helps to maximize profit while minimizing water and energy use

Where and when to irrigate

Three ways Three ways Measuring Soil-Water Checkbook Method Remote sensing

Where and when to irrigation Measuring soil waterMeasuring soil water

Quantitative methods Neutron Scatter Di-electric Constant MethodsGravimetric Soil Sampling

Qualitative methodsTensiometers Porous Blocks

Where and when to irrigation Checkbook method

The check-book method is an accounting approach for estimating how much soil-water remains in the effective root zone based on water inputs and outputs (like a daily balance on a bank account based on deposits and withdrawals)

Irrigation is scheduled when the soil-water content in the effective root zone is near the allowable depletion volume, otherwise irrigation should be delayed.

Where and when to irrigation

Remote sensing Satellite image and air photo Infrared thermometry is a more recently

developed technique to determine irrigation timing based on plant canopy temperature rather than soil moisture

How much to irrigate Enough irrigation water should be applied to

replace the depleted plant available water(PAW) within the root zone and to allow for irrigation inefficiencies

PI application example

Location: Richland, Washingon Farmer: Thayne Wiser Farm area: 2000 acres Research area:120 acres Irrigation Systems: self-propelled center-pivot

irrigation systems

PI application example

Research team Washington State University USDA-ARS A sprinkler manufacturer

Objectives Characterize soil water spatial variations Develop water-application prescriptions to meet the

often-conflicting needs for discrete areas in the field

Engineer a variable-rate sprinkler system to deliver water in precise amounts based on prescriptions

PI application example

Procedures: Mapping topography

Use 8-channel,L1,C/A-code DGPS to gather point data

Input point data to GIS software to generate topography map

                                                           

PI application example

Scouting the SoilGather georeferenced soil samples on 200-

foot gridsAnalyze soil texture, physical and chemical

propertiesCreate soil maps showing each soil

parameter as a separate GIS layer

PI application example Prescription Preparation

Determine management zones• 20 per field with the smallest area about one

acre• 100 management zones in 120 acres

Access GIS data layers using computer models, integrate climatic data, irrigation system characterization data, and irrigation scheduling procedures based on current soil-moisture levels

  

PI application example

Make decision about water needs of specific Make decision about water needs of specific zones to create management map(or zones to create management map(or prescription)prescription)

Use prescription to program the sprinkler heads Use prescription to program the sprinkler heads to deliver either more or less water in each to deliver either more or less water in each management zone.management zone.

PI application example Water monitor

Place 6 passive capillary (PCAP) soil-solute samplers in research circle at a depth of 3.5 feet to monitor soil water

Use Frequency domain reflectrometry (FDR) probes installed above PCAPs to assess soil moisture in real time

Place neutron-scattering access tubes, ceramic vacuum-extractor cups, and tipping-bucket rain gauges adjacent to each PCAP to verify soil moisture measurement

PI application example

Determine actual water use in each management zone and judge the effectiveness of the precision irrigation applications

Install an automated agricultural weather Install an automated agricultural weather station to collect climatic data every 15 station to collect climatic data every 15 minutesminutes

Connect all the monitoring devices to the Connect all the monitoring devices to the dataloggers dataloggers

PI application example

Water delivery systemDivided the length of the test pivot into 30

zones, having two to four sprinkler heads apiece. Each zone had its own programmable controller

Cycled the sprinklers on and off at selected intervals over a period of time to achieve the prescribed irrigation amount in a management zone

Precision irrigation application example I

Master Control systems Master computer collects pivot location and

controller status information The system communicates changes in

application rates for each of the 30 controllers according to the controller's location on the prescription map

The control system allows the irrigator to change, at the base computer, the prescription or decision criteria for any management zone at any time during the irrigation.

PI application example I

Master control system

GIS base mapIrrigation models

Real time prescriptionMaps and other software

Master computer

Pivot location and controller status data

Prescription instructions

Controllers

Questions ?