Irrigation and Water Management
What the domain covers
This domain tests how water reaches plants efficiently, how much to apply, and how to avoid waste, erosion, and salinity. Expect questions on irrigation methods, scheduling, soil moisture, and drainage.
Core rules and concepts
- Water requirement depends on crop stage, climate, soil, and evapotranspiration; young plants need less but frequent water.
- Drip delivers water near the root zone and saves water; sprinkler suits close-grown crops but wets foliage and can spread disease.
- Furrow and basin methods need levelled land and careful flow to avoid waterlogging and erosion.
- Schedule irrigation by feel or moisture meter, not by fixed habit; avoid midday irrigation in hot weather.
- Mulching, contouring, and rainwater harvesting conserve moisture.
- Poor drainage causes root asphyxiation and salt accumulation; leach excess salts where needed.
Worked example
A root zone holds about 20 mm of readily available water and the crop uses 4 mm per day. The interval is 20 ÷ 4 = 5 days, before stress. In practice, check soil moisture and adjust for rain and crop stage. The reasoning links soil storage to daily use; irrigating daily would waste water and leach nutrients.
Traps
- Applying the same schedule to seedlings and mature plants.
- Using saline water without checking crop tolerance or leaching.
- Ignoring drainage: more water cannot fix a waterlogged root zone.