Irrigation is the artificial application of water to soil for crop production. It supplements natural rainfall to maintain soil moisture levels adequate for plant growth. Irrigation systems are categorized by the method of water delivery: drip irrigation, sprinkler irrigation, flood irrigation, and subsurface irrigation. The choice of system depends on crop type, soil characteristics, water availability, and budget.
Drip irrigation delivers water directly to the plant root zone through a network of tubes, emitters, and drip tape. Water is applied slowly at a rate of 1 to 4 liters per hour per emitter, wetting only the root zone and minimizing evaporation losses. Drip irrigation is 85 to 95 percent efficient, compared to 50 to 70 percent for sprinkler systems. The system operates at 10 to 30 psi pressure and requires Water Filtration to prevent emitter clogging. Drip irrigation is the preferred method for vegetables, orchards, and vineyards.
Sprinkler systems distribute water through overhead spray nozzles that simulate rainfall. Types include impact sprinklers, rotary sprinklers, and fixed spray heads. Impact sprinklers are used for large areas and operate at 40 to 100 psi. Rotary sprinklers distribute water at a slower rate to reduce runoff. Fixed spray heads are used for small areas and operate at 20 to 30 psi. Sprinkler systems are suitable for lawns, pastures, and field crops.
Flood irrigation, also called surface irrigation, distributes water by gravity flow across the soil surface. Furrow irrigation directs water down rows between crop beds. Basin irrigation floods a level area surrounded by dikes. Flood irrigation is the least efficient method, with 40 to 60 percent water use efficiency, but requires the least equipment investment. It is used for row crops, rice, and pastures.
Subsurface drip irrigation (SDI) places drip lines 15 to 30 centimeters (6 to 12 inches) below the soil surface. SDI eliminates evaporation losses and surface runoff, achieving 95 percent efficiency. It is used for permanent crops such as orchards, vineyards, and alfalfa. SDI systems require careful management to prevent root intrusion into the emitters.