About Drip/Microirrigation

WHAT IS DRIP IRRIGATION

Drip/microirrigation systems are pressurized systems (i.e., water flows in the lines of the system under pressure) that enable the delivery of water and fertilizers in a frequent and localized manner from the source to the plant without any significant losses on the way and at much smaller application rates than conventional irrigation systems. This makes it possible to spoon-feed and maintain favourable moisture and nutritional environment for the plant and profitable crop yield.

The water from some sources (rivers, lakes, reservoirs) is pressurized by a centrifugal pump, while water from wells is usually pumped and pressurized by deep well pump. The pressurized water then flows through the main filter (mostly sand media filter as shown below) before entering the system to remove suspended particles that could clog drip lines and emitters.

Chemicals (e.g., fertilizers) are injected in the water flow, and this is one of the advantages of drip systems. The injection device is, usually, placed upstream (ahead) from the filter to enable the latter to separate the precipitates that may result from the injected chemicals before they enter the system (as illustrated in system layout below).

The water coming out of the filter flows to different piping and parts of the system at the design pressure then to the emitting devices (e.g., drippers, microsprinklers) that deliver water directly to the plant. Emitters installed on lateral lines are referred to as on-line emitters, or embedded in the lines and known as in-line emitters, with laterals laid on the ground surface. That is why these systems are referred to as surface drip. Such systems are usually used for orchard irrigation. In other instances laterals are buried (installed below ground surface) and referred to as subsurface drip or buried drip. For buried drip, lines are equipped with in-line emitters or drip tape may also be used. Buried drip is common for irrigation of tomatoes and other vegetable crops (see Fig's below & revolving pictures on front page).

The system is equipped with valves at specific locations for flow shutoff and for preventing flow reversal. Special valves are also installed in the system, as appropriate, to avoid the detriment of excessive pressure and the harmful effect of accumulation of air bubles in the lines. Control heads are installed at the entrance to each manifold with pressure regulating devices (as shown below) to maintain the design pressure and discharge uniformity. Shrader valves are also included in the head to check if the actual pressure of the flow entering the manifold is as expected. A screen to remove particles that may have entered the system downstream from the main filter (e.g. during localized repair work) is incorporated in the head to minimize clogging. Flushout arrangements are installed at the end of all lines (as shown below) to wash out debris. These componenets are included, as appropriate, in AgriDrip designs.

Drip systems can be used for irrigating most crops on most soils (heavy, sandy, shallow, steep grounds). Crops that are salt tolerant (e.g., tomato, cotton) when irrigated with relatively saline water could be more productive under drip than under conventional irrigation methods because of maintaining steady moist environment around the crop root under drip which reduces the undesirable effect of salinity.

Drip systems are not really costly, compared to conventional irrigation systems, if the benefits of drip including improvement of crop yield, water saving, saving on fertilizer cost, protecting ground water and labor saving are taken into consideration. Drip systems can be site-specific designed and easily automated. Actually, the possibilities with drip irrigation are unlimited.

However, it is essntial to have a well designed and properly managed and maintained
drip system with proper irrigation scheduling that can apply water requirements uniformly and efficiently to the crop to achieve the above-listed benefits. AgriDrip provides the proper system designs and the necessary manuals (how-to books, please visit "Drip Books" page on this site) for managing and proactively maintaining drip systems in good running conditions.