PRESSURIZED SPRINKLER IRRIGATION
How It Works:
Sprinklers distribute drops of water over the crop, imitating rain. For permanent installations, pipes can be laid on the ground or buried (solid set). For mobile installations, pipes may be moved by hand or supported by wheel structures that advance the sprinklers along a field (linear moves, wheel lines). Center pivot systems, similar to linear moves, rotate about well heads that supply water from underground rather than from canals. (The Bureau of Reclamation manages only reservoir and canal water from federal projects.)
Movable pipe and wheel line
solid set: flowers, vegetables, orchards
hand moves: cotton, tomatoes
linear moves: field crops, vegetable
When It Works Well:
Sprinkler systems are well suited for uneven terrain. These systems apply water most uniformly when there is little wind; windy conditions can spoil the application pattern. Careful monitoring and water scheduling reduce over-watering. For linear moves, downward oriented drop tubes deliver water closer to the crop with less wind scatter. The objective: Match the application rate to the infiltration rate, so that the soil is wetted without water pooling upon the surface where it evaporates or runs off the end of the field.
Costs and Benefits:
Sprinkler irrigation can serve many purposes: frost protection, seed germination, leaf canopy cooling, delivery of agricultural chemicals mixed with the irrigation water, and replenishing soil moisture during the off-season. But pressurized, elevated pipes also require expensive electrically powered pumping. The degree of application uniformity determines the efficiency of a sprinkler system. When water is unevenly distributed, supplying sufficient water to the least watered areas means that everywhere else is over-watered. Compared to surface irrigation methods, sprinklers permit better control over application amounts.
Low Pressure Micro Irrigation