IRRIGATION TECHNOLOGYDECISIONS: 

MICROIRRIGATION

Dana O. Porter, PhD, PEResearch and Extension Agricultural Engineer

Texas A&M AgriLife Research and Extension Center – LubbockDepartment of Biological and Agricultural Engineering

Efficient, advanced irrigation technologies in the Texas High Plains:

Water capacity is a limiting factor throughout most of the region

Agricultural producers are progressive, relatively rapid adopters of technology ‐‐‐ “critical mass” of peer producers and success stories

The technologies are “good fits” for farm operations (fields, crops, managers) in the Texas High Plains 

Excellent applied research programs in the area (Texas A&M Halfway, Bushland, Amarillo and Etter; USDA‐ARS‐Bushland)

Critical mass of well‐qualified and experienced irrigation dealers, designers, installers – ready access to technical expertise and support

USDA‐NRCS EQIP cost‐share and low interest loan options help offset high capital costs

Good collaboration among research, extension, industry, producers

Efficient advanced irrigation technologies: Important considerations

- suitability or adaptability of a technology to local production systems and conditions

- economic feasibility

- availability of irrigation industry, research and educational infrastructure and resources to support applications in the field

Successful application of irrigation technologies requires good design, installation, maintenance, and management.

Irrigation in Context:  Integrated Production Systems

Goals:   Crop yield, quality

Production efficiencyWater, Nitrogen, and Energy EfficiencyEfficiency and efficacy of all inputs

Manage the overall system for high returnOptimal response to inputsUnderstanding limiting factorsReducing losses and unnecessary inputs

Nutrient managementVariety selectionIntegrated Pest Management (IPM)Water management (irrigation, rainfall, soil moisture)

MICROIRRIGATION

Subsurface drip irrigation

Surface drip irrigation

Shallow subsurface drip irrigation

Microspray irrigation 

Microspray Irriga on

Photo: USDA‐NRCS University of California Agriculture and Natural Resources

University of California Agriculture and Natural Resources

Microspray (microtube) Irriga on

Surface drip irriga on

Microirrigation on trellises in a vineyard

Shallow subsurface drip irriga on ‐ SSDI

Shallow subsurface drip irriga on

Subsurface Drip Irriga on ‐ SDI Photo courtesy: Jim Bordovsky

Filtra on

Disc filter

Media filters

Hydrocyclone Sand Separator

Soil Moisture Uptake by Plant Roots

Plants will get most of their water from the upper part of the root zone.  As the shallow water is depleted, the plant will extract water from deeper in the profile – if it has roots there, and if water is available.

Limits to the Root Zone Depth

If roots encounter a confining condition in the soil profile, the effective root zone is limited.  

Examples of confining conditions: compaction zone, caliche layer, dry layer, saturated layer, salt accumulation

Subsurface Drip IrrigationRoot Zone

every row alternate furrows

Potential salt & toxic element accumulation zone

Wetted area affects size of root zone

Subsurface Drip Irriga on: Tape Placement & Spacing

every row alternate furrows

Other configura ons:

SDI vs. Center Pivot

Photo courtesy: Jim Bordovsky

Rodent Damaged Drip Tape

SDI peanuts with cotton in the background, Gaines County, 2002. Timely rainfall in the spring made a big difference in germination in this sandy soil.

Subsurface Drip IrrigationAdvantages and Disadvantages

Advantages offered by SDI+ improved water use efficiency + energy savings+ improved nutrient management (spoon feeding)+ improved crop yield and/or quality+ decreased labor requirements+ system may be automated

Disadvantages of SDI  ‐ high initial cost ‐ no deep tillage for control of disease and pests ‐ some designs offer limited flexibility‐ potential germination problems (esp. in coarse soils)‐ increased management & maintenance requirements‐ potential damage due to rodents and other influences

IRRIGATION TECHNOLOGY

DesignLayout InstallationMaintenanceManagement

Keys to successful implementation

Advanced irrigation technologies are good tools for good managers.   Technology can reduce labor requirements and improve management options, but it does not replace good management.

SDI TipsStart with a good design and installation.  Be realistic with well capacities & management capabilities. 

Be diligent in system maintenancefiltration, flushing, chemical injection as needed).  Monitor flow and pressure as indicators of system performance and as trouble‐shooting aids.

Manage irrigation and other crop inputs for optimal esults.  SDI is a good tool for a good manager.

SDI SYSTEM MAINTENANCE

Regular flushing of drip lines is essential.  

Proper system design facilitates flushing. ‐ design must address flush volume / pressure / velocity‐ design should address operator considerations (ease of flushing, access to flush valves, etc.)

Chemical Injection

Chemical injection is necessary with row crop drip irrigation systems.

‐ prevent emitter plugging

‐ fertilization of a limited root zone

‐ limited IPM applications

Chemical Injectionprevent emitter plugging 

* requirements depend upon water quality

acid injection ‐ prevents calcium and magnesium carbonate precipitation; may be effective in controlling slimy bacteria; may be used to control root intrusion; soil pH adjustment may be warranted for other agronomic reasons.

chlorine ‐ controls growth of algae and slimy bacteria

Special requirements (i.e. H2O2 to prevent Mn precipitation) 

SDI Water Quality Considerations

Recommended water quality tests

Electrical Conductivity (EC) ‐measured in ds/m or mmho/cm – a measure of total salinity or total dissolved solids

pH ‐ a measure of acidity ‐ where 1 is very acidic, 14 is very alkaline, and 7 is neutral

Cations ‐measured in meq/L, (milliequivalent/liter), includes: Calcium (Ca), Magnesium (Mg), and Sodium (Na)

Anions ‐measured in meq/L, includes: Chloride (Cl), Sulfate (SO4), Carbonate (CO3), and Bicarbonate (HCO3)

And others…. consult recommended references

Chemical InjectionFertilization, “Fertigation”

“spoon feeding” to meet crop requirements

* fertilizer savings and/or better crop response to applied nitrogen fertilizer

* reduced fertilizer costs

* reduced leaching losses 

* address issue of limited root zone and other nutrient access factors

Chemical InjectionConsiderations:

Chemical labels ‐ EPA requires statements onpesticide labels addressing:‐ type of irrigation system(s)‐ risks associated with non‐uniform water application‐ calibration‐ backflow protection requirements

Backflow prevention – required!!

Injection (mixing, injection pumps, precipitate “jar” testing)  

Compatibility with water quality 

Note: these values do not take into account irrigation efficiency.

USEFUL INFORMATION, 

TOOLS AND RESOURCES

USDA‐ARSOgallala Aquifer Program

USDA‐NIFAMicroirrigation Research Group

h p://www.ksre.ksu.edu/sdi/

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirriga on Systems h p://micromaintain.ucanr.edu/#

Maintenance of Microirrigation Systems

http://micromaintain.ucanr.edu/#

ww.ksre.ksu.edu/mil/ 

https://watermgmt.tamu.edu/

watermgmt.tamu.edu/

Texas High Plains ET Network Weather Station, Lubbock, TX

757778

Subsurface Drip Irrigation ubsurface Drip Irrigation has gained a lot of ground in e High Plains – particularly in cotton production systems the Texas Southern High Plains.

DI is highly efficient, with little or no risk of runoff or rface evaporation (although as with any irrigation method, excessive

gation applications can be lost through deep percolation.)

sson from the drought: Good design – with adequate ning – is critical to flexibility to adjust to declining water pacities.

anagement and maintenance are key.

Subsurface Drip Irrigation 

Subsurface Drip Irrigation is a good tool for a good manager.  It does not solve all problems, and it does not fit every operation.  

SDI fits well for a wide variety of applications, but shows particular advantage for operations with‐ Limited irrigation capacities‐ Small or irregularly shaped fields‐ Management capabilities to manage and maintain 

the systems (equipment, chemicals, intensive crop management)