Maharashtra HSC NSQF Micro Irrigation Technician flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Distribution uniformity (DU)

Ratio of the average of the lowest quarter of emitter or catch-can readings to the overall mean, expressed as a percentage. Drip design target is 85% or higher.

Emission uniformity (EU)

Uniformity measure combining manufacturing variation and pressure differences: EU = 100 × (1 − 1.27 × CV ÷ √n), where CV is the emitter coefficient of variation and n the emitters per plant.

Pressure-compensating emitter

A dripper with a flexible or labyrinth membrane that keeps discharge nearly constant across roughly 0.5 to 4.0 bar, allowing long laterals and level or gently sloping blocks.

Subsurface drip irrigation

Drip laterals buried 15 to 30 cm below the soil surface, reducing evaporation and surface damage while requiring care against root intrusion and rodent damage.

Field capacity

Soil water content retained after excess water drains under gravity, roughly at −0.33 bar matric potential. It is the upper limit of water available to plants.

Permanent wilting point

Soil water content at about −15 bar where plants can no longer extract water and remain permanently wilted. The difference from field capacity is available water.

Management allowed depletion

The fraction of available soil water that may be consumed before irrigation is triggered. Typical values are 0.5 for field crops and 0.3 to 0.4 for horticulture.

Crop evapotranspiration (ETc)

Water lost by the crop through transpiration and soil evaporation, computed as the reference evapotranspiration ETo multiplied by the crop coefficient Kc for the growth stage.

Tensiometer

A sealed water-filled tube with a porous ceramic tip and vacuum gauge that reads soil matric potential directly, used to trigger irrigation near the depletion threshold.

Total dynamic head

The sum of static lift, friction losses in suction and delivery pipes, required system operating pressure, and elevation difference, used to select the pump duty point.

Media sand filter

A pressure vessel with graded sand or gravel beds that traps fine organic and inorganic particles. It is cleaned by backwashing when differential pressure rises about 0.5 to 0.7 bar.

Venturi injector

A fertigation device that draws stock solution through suction created by a pressure differential of about 0.3 to 0.7 bar across a converging-diverging throat. No moving parts.

Backflow prevention

A check valve plus vacuum breaker installed between the injection point and the water source, stopping fertiliser or chemical from contaminating the supply or drinking water.

Screen filter mesh rating

The number of openings per linear inch of screen. Drip systems generally need 120 to 200 mesh, while micro-sprinklers can accept coarser 80 to 100 mesh filtration.

Hazen-Williams equation

An empirical pipe friction formula relating head loss to flow, pipe diameter, length, and a roughness coefficient C. It is used to size laterals, sub-mains, and mainlines.

Christiansen uniformity coefficient

A catch-can uniformity measure: CU = 100 × (1 − sum of absolute deviations from the mean ÷ total catch). Sprinkler designs target 80% or higher.

Allowable pressure variation

The pressure difference along a lateral or sub-main that keeps flow variation within about 10 percent, roughly a 20 percent pressure variation for non-compensating emitters.

Basic soil intake rate

The steady infiltration rate of a soil. Sprinkler application rate must stay below it to avoid ponding and runoff, especially on clay soils with low intake.

Flush valve

A valve fitted at the far end of laterals and sub-mains to discharge sediment and debris during routine flushing. It must be opened before commissioning and periodically thereafter.

Pressure test

A commissioning check that pressurises the network to 1.5 times design working pressure, or the pipe rated test pressure, and holds it to detect leaks at joints and fittings.

Catch-can test

A sprinkler field test using cans on a grid within the spacing, run for a set time, with depths measured to compute the uniformity coefficient and application rate.

Chlorination of drip lines

Injection of chlorine to about 1 to 2 ppm free chlorine to dissolve organic and bacterial clogging in laterals and emitters, followed by flushing with clean water.

Differential pressure clogging signal

A rise of about 0.5 to 0.7 bar across a filter indicates clogging. Backwash first, then inspect and clean or replace the screen or disc element.

Acid injection for scale

Controlled injection of acid to dissolve calcium carbonate scale in emitters and lines, always adding acid to water and flushing afterwards to protect the crop.

Pump cavitation symptoms

Noise, vibration, and falling discharge caused by vapour bubbles collapsing at the impeller, usually from a clogged suction strainer, air leak, or excessive suction lift.

Electrical safety at pump panel

Working earth connection, ELCB or RCCB protection, and an isolator at every pump panel. Isolate the supply before opening the panel or touching a wet pump.

Confined space entry rule

Sumps, tanks, and borewell pits require gas testing, a harness, and a standby observer outside. Entry alone is prohibited regardless of the task duration.

Acid handling rule

Always add acid slowly to water, never water to acid, while wearing gloves, goggles, and a face shield, with an eye-flush water source kept nearby.

Emitter count per hectare

Computed as 10,000 square metres divided by the product of row spacing and emitter spacing in metres, giving the number of drippers used for bottom-up costing.

Subsidy documentation set

Land records, soil and water test reports, layout drawing, quotation from an empanelled supplier, and beneficiary bank and identity details, submitted for micro irrigation subsidy.

Job card

A field record listing farmer details, survey number, crop, area, materials issued, labour hours, commissioning readings, and the farmer's signature on completion.

As-built drawing

A post-installation layout showing field boundary, blocks, mainline and sub-main routes, lateral spacing, valve numbers, and headworks location with scale and north arrow.