Micro Irrigation Fundamentals and System Types
What the exam tests here
Micro irrigation means applying water at low pressure and low discharge close to the plant's root zone. This domain tests system classification, the function of each component, realistic efficiency figures and the reasoning behind choosing drip, sprinkler, micro-sprinkler or bubbler for a given field.
Core rules
- Typical application efficiency: surface flooding 40–60%, sprinkler 70–80%, drip 85–95%.
- Drip: emitter discharge 2–8 lph, operating pressure about 1.0–1.5 kg/cm², laterals 12–20 mm. It wets only 30–50% of the surface - that is a feature, not a defect, because it limits weed growth and evaporation.
- Sprinkler: nozzle discharge is quoted in m³/h, pressure 2–3.5 kg/cm². Best for close-growing field crops (wheat, gram, groundnut, onion) and for germination and frost protection.
- Micro-sprinkler and bubbler: 30–150 lph, used in orchards and wide-spaced crops where a larger wetted basin is wanted.
- Standard drip sequence: source → pump → filter → fertigation unit → main → submain → lateral → emitter, with valves, air-release and flush points.
Worked example
A farmer with 1 ha of onion on sandy loam and a 5 hp well asks for drip. Reasoning: onion is densely planted with shallow roots; sprinkler at 12 × 12 m spacing is cheaper per hectare and covers the crop canopy; drip would need very close lateral spacing (0.6–0.9 m) and many emitters, raising cost sharply. Recommend sprinkler, and reserve drip for a high-value wide-spaced crop such as tomato on plastic mulch or mango with two emitters per tree.
Traps that cost marks
- Treating "efficiency" and "uniformity" as synonyms.
- Claiming drip suits paddy.
- Forgetting that drip does not leach salts unless extra irrigation or rain is given.
- Quoting sprinkler pressure as lower than drip; it is higher.
Quick recall
Drip for high-value row and orchard crops; sprinkler for field crops; bubbler for trees.