Drip irrigation, also known as trickle irrigation or micro irrigation or localized irrigation , is an irrigation method which saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes, tubing, and emitters.It is done with the help of narrow tubes which delivers water directly to the base of the plant.

History

Drip irrigation has been used since ancient times when buried clay pots were filled with water, which would gradually seep into the grass. Modern drip irrigation began its development in Afghanistan in 1866 when researchers began experimenting with irrigation using clay pipe to create combination irrigation and drainage systems. In 1913, E.B. House at Colorado State University succeeded in applying water to the root zone of plants without raising the water table. Perforated pipe was introduced in Germany in the 1920s.

Usage of plastic to hold and distribute water in drip irrigation was developed in Australia by Hannis Thill. Refinement of this idea (involving a plastic emitter) was furthered in Israel by Simcha Blass and his son Yeshayahu. Instead of releasing water through tiny holes, blocked easily by tiny particles, water was released through larger and longer passageways by using velocity to slow water. Their company, Netafim later developed and patented the first surface drip irrigation emitter.

In the United States, in the early 1960s, the first drip tape, called Dew Hose, was developed by Richard Chapin of Chapin Watermatics (first system established during 1964). Beginning in 1989, Jain irrigation helped pioneer effective water-management through drip irrigation in India. Jain irrigation also introduced the `Integrated System Approach’, One-Stop-Shop for Farmers, `Infrastructure Status to Drip Irrigation & Farm as Industry.’ The latest developments in the field involve even further reduction in drip rates being delivered and less tendency to clog.

Modern drip irrigation has arguably become the world’s most valued innovation in agriculture since the invention of the impact sprinkler in the 1930s, which offered the first practical alternative to surface irrigation. Drip irrigation may also use devices called micro-spray heads, which spray water in a small area, instead of dripping emitters. These are generally used on tree and vine crops with wider root zones. Subsurface drip irrigation (SDI) uses permanently or temporarily buried dripperline or drip tape located at or below the plant roots. It is becoming popular for row crop irrigation, especially in areas where water supplies are limited or recycled water is used for irrigation. Careful study of all the relevant factors like land topography, soil, water, crop and agro-climatic conditions are needed to determine the most suitable drip irrigation system and components to be used in a specific installation.

Advantage and disadvantages

The advantages of drip irrigation are:

• Minimized fertilizer/nutrient loss due to localized application and reduced leaching.
• High water application efficiency.
• Levelling of the field not necessary.
• Ability to irrigate irregular shaped fields.
• Allows safe use of recycled water.
• Moisture within the root zone can be maintained at field capacity.
• Soil type plays less important role in frequency of irrigation.
• Minimized soil erosion.
• Minimized weed growth
• Highly uniform distribution of water i.e., controlled by output of each nozzle.
• Lower labour cost.
• Variation in supply can be regulated by regulating the valves and drippers.
• Fertigation can easily be included with minimal waste of fertilizers.
• Foliage remains dry thus reducing the risk of disease.
• Usually operated at lower pressure than other types of pressurised irrigation, reducing energy costs.

The disadvantages of drip irrigation are:

• Expense. Initial cost can be more than overhead systems.
• Waste. The sun can affect the tubes used for drip irrigation, shortening their usable life. Longevity is variable.
• Clogging. If the water is not properly filtered and the equipment not properly maintained, it can result in clogging.
• Drip irrigation might be unsatisfactory if herbicides or top dressed fertilizers need sprinkler irrigation for activation.
• Drip tape causes extra cleanup costs after harvest. You’ll need to plan for drip tape winding, disposal, recycling or reuse.
• Waste of water, time & harvest, if not installed properly. These systems require careful study of all the relevant factors like land topography, soil, water, crop and agro-climatic conditions, and suitability of drip irrigation system and its components.
• Germination Problems. In lighter soils subsurface drip may be unable to wet the soil surface for germination. Requires careful consideration of the installation depth.
• Salinity. Most drip systems are designed for high efficiency, meaning little or no leaching fraction. Without sufficient leaching, salts applied with the irrigation water may build up in the root zone, usually at the edge of the wetting pattern. On the other hand, drip irrigation avoids the high capillary potential of traditional surface-applied irrigation, which can draw salt deposits up from deposits below.

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