Micro Irrigation Systems: Components, Types and Layout
What the exam calls a micro irrigation system
This domain tests the head control unit, mainline, submain, manifolds, laterals, emitters, valves, air-release valves, pressure gauges, flow meter and flush points. It also tests surface, subsurface, inline, online, pressure-compensating (PC) and non-PC drip, plus micro-sprinkler and bubbler layouts.
Core rules
- The head unit normally includes pump, filtration, pressure regulator, fertigation port, and monitoring; filters protect emitters from clogging.
- Emitter discharge depends on pressure; PC emitters hold a nearly constant flow over a pressure range, non-PC do not.
- Laterals should run along the contour where possible; submain size and valve placement limit pressure variation.
- Provide flush valves at lateral ends and air-release valves at high points.
- Do not mix PC and non-PC emitters on one zone without checking pressure and flow.
Worked example
A 0.2 ha block is 50 m × 40 m. Laterals are spaced 1.0 m apart and emitters 0.5 m apart, each 4 L/h. Number of laterals = 40 ÷ 1.0 = 40. Emitters per lateral = 50 ÷ 0.5 = 100. Total emitters = 40 × 100 = 4,000. Block flow = 4,000 × 4 = 16,000 L/h = 16 m³/h. If the block is split into four zones, each zone needs about 4 m³/h, which affects mainline and valve size.
Traps
Do not use total field area when only the planted strip is wetted; do not forget flush and air valves; do not size a zone from emitter count alone without pressure loss; do not place a non-PC lateral on a long slope without pressure compensation.