Irrigation, Agriculture and Crop Water Productivity
This domain tests irrigation efficiency and crop water productivity. Questions compare irrigation potential with actual use, crop choice, scheduling and micro-irrigation.
Core rules
- Irrigation potential is not delivered water. Storage, canal loss, land development and cropping patterns determine actual irrigation.
- Crop water productivity is output per unit of water consumed, not per hectare. Sugarcane consumes far more water than soybean, cotton or pulses; in low-rainfall parts of Maharashtra it concentrates demand.
- Drip and sprinkler systems can raise field application efficiency, but they work only with scheduling, filtration and maintenance.
Worked example
A farmer has 6,000 m3 of water, equivalent to 600 mm over 1 ha. Sugarcane seasonal ET is about 2,000 mm, so the water can fully irrigate only 0.3 ha. Soybean ET is about 450 mm, so the same water could support about 1.3 ha. The reasoning is volume divided by crop water depth: 6,000 m3 ÷ (2,000 mm × 10,000 m2/ha) = 0.3 ha. The higher-value crop may still be rational, but the water opportunity cost must be explicit.
Traps
- Equating created irrigation potential with water actually delivered.
- Comparing crops per hectare rather than per cubic metre.
- Ignoring canal and conveyance losses.
- Assuming drip irrigation removes the need for scheduling.