natural resources conservation service micro irrigation is it the right choice and design...

Natural Resources Conservation Service

Micro IrrigationMicro Irrigation

Is it the right choice and Is it the right choice and design considerationsdesign considerations


First of all, micro irrigation First of all, micro irrigation is….is….……the broad classification of frequent, low volume, the broad classification of frequent, low volume,

low pressure application of water on or beneath low pressure application of water on or beneath the soil surface by drippers, drip emitters, the soil surface by drippers, drip emitters, spaghetti tube, subsurface or surface drip tube, spaghetti tube, subsurface or surface drip tube, basin bubblers, and spray or mini sprinkler basin bubblers, and spray or mini sprinkler systems. It is also referred to as drip or trickle systems. It is also referred to as drip or trickle irrigation. (NEH Part 652, Irrigation Guide, ‘97)irrigation. (NEH Part 652, Irrigation Guide, ‘97)

……an irrigation system for distribution of water an irrigation system for distribution of water directly to the plant root zone by means of directly to the plant root zone by means of surface or subsurface applicators. (Draft PS surface or subsurface applicators. (Draft PS 441, ‘00)441, ‘00)


Why would I use micro?Why would I use micro? high uniformity with good design (90+ % achievable)high uniformity with good design (90+ % achievable)

MAY result in excellent efficiency MAY result in excellent efficiency inputs of water, power, inputs of water, power, and chemicalsand chemicals

growth/productiongrowth/production less wetted surface area less wetted surface area evaporation & evaporation & weed weed

problemsproblems good in windy conditions (good in windy conditions (Uniformity & Uniformity & evaporation) evaporation) good in undulating or steep areas (good in undulating or steep areas (Uniformity)Uniformity) excellent system control with automationexcellent system control with automation system flexibility system flexibility

odd “field” shapesodd “field” shapes supply nutrients to a specific point so spacing/variety of plant supply nutrients to a specific point so spacing/variety of plant

is not limitingis not limiting soils with low water holding capacity (frequent, low volume soils with low water holding capacity (frequent, low volume

applications)applications)


Why would I use micro? Why would I use micro? (cont.)(cont.) low operating costlow operating cost

high efficiency with low pressures & flow rates high efficiency with low pressures & flow rates energy energy savings savings

less laborless labor odor control for waste water applications (esp. odor control for waste water applications (esp.

subsurface)subsurface) climate controlclimate control

or or temperature temperature or or humidity humidity

““disease” controldisease” control eliminate wetting of tree trunkseliminate wetting of tree trunks eliminate wetting of leaf/fruiteliminate wetting of leaf/fruit

easily adapted to automationeasily adapted to automation …………any others?…...any others?…...


Why wouldn’t I use micro?Why wouldn’t I use micro? Issues associated with “dirty” waterIssues associated with “dirty” water

potential clogging of emitterspotential clogging of emitters cost of filtrationcost of filtration

High Level of O&M RequiredHigh Level of O&M Required High Pest Damage PotentialHigh Pest Damage Potential High Initial CostHigh Initial Cost

Most, if not all, of these issues can be Most, if not all, of these issues can be overcome but at some point it becomes a overcome but at some point it becomes a matter of economicsmatter of economics


So, if micro is right for the So, if micro is right for the situation…..situation…..

Micro Design Micro Design ConsiderationsConsiderations


Information Needed for Micro Information Needed for Micro DesignDesign

Soil Characteristics (Water Holding Capacity, pH, etc.)Soil Characteristics (Water Holding Capacity, pH, etc.) Tree/Shrub/Crop CharacteristicsTree/Shrub/Crop Characteristics

Layout (spacing, numbers, etc.)Layout (spacing, numbers, etc.) Tree/Shrub/Crop Water Requirements over timeTree/Shrub/Crop Water Requirements over time Root Zone over timeRoot Zone over time Sensitivity to Available Moisture (MAD)Sensitivity to Available Moisture (MAD) Sensitivity to Water/Soil QualitySensitivity to Water/Soil Quality

Good topographic survey - at least 2 foot intervals.Good topographic survey - at least 2 foot intervals. Water & Power SourceWater & Power Source

LocationLocation QuantityQuantity QualityQuality

Owner/Operator Characteristics & DesiresOwner/Operator Characteristics & Desires



NRCS Standards, Specifications & NRCS Standards, Specifications & ReferencesReferences

PS and GS 380 Windbreak/Shelterbelt EstablishmentPS and GS 380 Windbreak/Shelterbelt Establishment “…“…supplemental or permanent watering of the planting will be supplemental or permanent watering of the planting will be

evaluated in areas with less than 20 inches average annual evaluated in areas with less than 20 inches average annual precipitation……”precipitation……”

“… “… Use Idaho Forestry TN 14 (12/93) for water requirements.”Use Idaho Forestry TN 14 (12/93) for water requirements.” ““soak soil to 3 to 5 ft depth”soak soil to 3 to 5 ft depth” MAD of 50 to 60%MAD of 50 to 60% if poly fabric mulch used, supplemental water use may be if poly fabric mulch used, supplemental water use may be

reduced by up to 50%reduced by up to 50% PS 441 Irrigation System, Trickle (‘82)PS 441 Irrigation System, Trickle (‘82)

design application efficiency not to exceed 90%design application efficiency not to exceed 90% for individual laterals, individual emitter q ± 15% of average q for individual laterals, individual emitter q ± 15% of average q main and submains must meet PS 430main and submains must meet PS 430 ““A filtration system shall be provided…..”A filtration system shall be provided…..”



NRCS Standards, Specifications & NRCS Standards, Specifications & ReferencesReferences

Draft PS 441 Irrigation System, Microirrigation (‘00)Draft PS 441 Irrigation System, Microirrigation (‘00) max time of operation for design is 22 hr/daymax time of operation for design is 22 hr/day design application efficiency not to exceed 90%design application efficiency not to exceed 90% # & spacing of emitters (P# & spacing of emitters (Pw) based on NEH 623, Ch. 7) based on NEH 623, Ch. 7 manufacturer’s coefficient of variationmanufacturer’s coefficient of variation for individual subunits (blocks), individual emitter q ± 10% of for individual subunits (blocks), individual emitter q ± 10% of

average q (total variation of 20% allowed)average q (total variation of 20% allowed) main and submains must meet PS 430main and submains must meet PS 430 ““A filtration system shall be provided…..” with constraintsA filtration system shall be provided…..” with constraints other: pressure regulators, chemical treatment, flushing, other: pressure regulators, chemical treatment, flushing,

subsurface installation, chemigation, germination, water subsurface installation, chemigation, germination, water quality, salinity issuesquality, salinity issues

NEH Part 623, Irrigation, Chapter 7, Trickle IrrigationNEH Part 623, Irrigation, Chapter 7, Trickle Irrigation


Micro Design Micro Design ConsiderationsConsiderationsNRCS Standards, Specifications & ReferencesNRCS Standards, Specifications & References

NEH Part 652, Irrigation Guide, Chapter 6, Irrigation System NEH Part 652, Irrigation Guide, Chapter 6, Irrigation System Design (9/97) - WindbreaksDesign (9/97) - Windbreaks

if designing to irrigate throughout lifespan, use NEH 623, Ch. 7if designing to irrigate throughout lifespan, use NEH 623, Ch. 7 if designing just for establishmentif designing just for establishment

design to last at least first 5 yearsdesign to last at least first 5 years after initial establishment of trees/shrubs water applications should after initial establishment of trees/shrubs water applications should

be greater in volume and less frequent to encourage root zone be greater in volume and less frequent to encourage root zone developmentdevelopment

suggests augering and backfilling a deep, small diameter hole near suggests augering and backfilling a deep, small diameter hole near each tree/shrub to allow deeper penetration of water and, hence, each tree/shrub to allow deeper penetration of water and, hence, deeper rootingdeeper rooting

for arid & semiarid climates, apply water early in spring after soil for arid & semiarid climates, apply water early in spring after soil thaws to fill soil profilethaws to fill soil profile

discontinue watering in the fall before freezing to encourage discontinue watering in the fall before freezing to encourage “hardening” (perhaps should irrigate after “hardening,” however)“hardening” (perhaps should irrigate after “hardening,” however)

do not provide full irrigationdo not provide full irrigation


Micro Design Micro Design ConsiderationsConsiderations System reliability/management is importantSystem reliability/management is important

soil volume wetted soil volume wetted WHC WHC “dry” quicker “dry” quicker Flushing abilityFlushing ability

individual lateralsindividual laterals connect ends with flushing main (also gives system connect ends with flushing main (also gives system

resiliency)resiliency) required velocity at end of lateral > than operating velocityrequired velocity at end of lateral > than operating velocity

Runoff - Infiltration Rate vs. Application RateRunoff - Infiltration Rate vs. Application Rate frequent applications frequent applications typically “wetter” soils typically “wetter” soils

infiltration capacity during storm eventsinfiltration capacity during storm events effects of weed barrier fabriceffects of weed barrier fabric point sourcespoint sources

Saline/Sodic conditionsSaline/Sodic conditions frequent applications frequent applications continuous dilution of salty water continuous dilution of salty water but, “salt profile” can be moved back into root zone with but, “salt profile” can be moved back into root zone with

precipprecip System DrainageSystem Drainage

frequent cycling frequent cycling overapplication in drainage areas overapplication in drainage areas


Micro Design Procedure (Irrigation Micro Design Procedure (Irrigation Guide)Guide)

NOT a linear procedure since these steps are NOT a linear procedure since these steps are interrelatedinterrelated

Step 1: Determine net amount of water requiredStep 1: Determine net amount of water required Step 2: Emitter designStep 2: Emitter design Step 3: Subunit/block designStep 3: Subunit/block design Step 4: Size laterals, submains, & mainsStep 4: Size laterals, submains, & mains Step 5: Pump selectionStep 5: Pump selection Step 6: Filtration designStep 6: Filtration design Steps 7 & 8: Fertilizer & chemical injection designSteps 7 & 8: Fertilizer & chemical injection design Step 9: Pressure gauge, valves, drains, measuring Step 9: Pressure gauge, valves, drains, measuring

devicesdevices Step 10: Irrigation scheduling planStep 10: Irrigation scheduling plan Step 11: O&M planStep 11: O&M plan

natural resources conservation service micro irrigation is it the right choice and design...

Documents

u issues

temperature v

achievable v

chemicals v growthproduction

u soils

subsurface u climate

u high uniformity

humidity u disease control