Drip irrigation only option to fight water shortageMarch 16, 2015
Karachi: Sindh despite its vast lands and hard working farmers is still a deprived province, as its huge area is still not under cultivation because of limited irrigation network. However, the fate of Sindh could be changed if it opts for drip irrigation system which could turn it into the grain basket of Pakistan.
Shortage of irrigation water in Pakistan including Sindh is an inevitable truth. The shortfall of water is increasing very rapidly with the passage of time. Among the 25 most populous countries in 2009 South Africa, Egypt and Pakistan are the most water limited nations. According to the United Nations World Water Development Report the total actual renewable water resources in Pakistan decreased from 2961 cubic meters per capita in 2000 to 1420 cubic meters in 2005. If the current trends continue it could go as low as 550 cubic meters by 2025. Our per acre production of different crops is less than many developing countries of the world. However, using the drip irrigation method the fate of the province as well as the country could be changed
Drip irrigation trend of row crops is increasing throughout the world. This irrigation method has the advantage of precisely applying irrigation water in the root zone, thus offering the potential of increased profit due to reduced water, fertilizer, cultural costs and increased revenue due to increased yield.
This system works with a network of valves, pipes, tubing, and emitters. The irrigation is done through narrow tubes that deliver water directly to the base of the plant.
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.
Components used in drip irrigation include pump or pressurized water source; water filter(s) or filtration systems: sand separator, fertigation systems (Venturi injector) and chemigation equipment (optional); backwash controller (Backflow prevention device); pressure control valve (pressure regulator); main line (larger diameter pipe and pipe fittings); hand-operated, electronic, or hydraulic control valves and safety valves; smaller diameter polytube (often referred to as “laterals”); poly fittings and accessories (to make connections), and emitting devices at plants (emitter or dripper, micro spray head, inline dripper or inline drip tube).
In drip irrigation systems, pump and valves may be manually or automatically operated by a controller.
Most large drip irrigation systems employ some type of filter to prevent clogging of the small emitter flow path by small waterborne particles. New technologies are now being offered that minimize clogging. Some residential systems are installed without additional filters since potable water is already filtered at the water treatment plant. Virtually all drip irrigation equipment manufacturers recommend that filters be employed and generally will not honor warranties unless this is done. Last line filters just before the final delivery pipe are strongly recommended in addition to any other filtration system due to fine particle settlement and accidental insertion of particles in the intermediate lines.
Drip and subsurface drip irrigation is used almost exclusively when using recycled municipal waste water. Regulations typically do not permit spraying water through the air that has not been fully treated to potable water standards.
Properly designed, installed, and managed, drip irrigation may help achieve water conservation by reducing evaporation and deep drainage when compared to other types of irrigation such as flood or overhead sprinklers since water can be more precisely applied to the plant roots. In addition, drip can eliminate many diseases that are spread through water contact with the foliage. Finally, in regions where water supplies are severely limited, there may be no actual water savings, but rather simply an increase in production while using the same amount of water as before. In very arid regions or on sandy soils, the preferred method is to apply the irrigation water as slowly as possible.
The advantages of drip irrigation include fertilizer and nutrient loss is minimized due to localized application and reduced leaching.
Water application efficiency is high if managed correctly Field leveling is not necessary. Fields with irregular shapes are easily accommodated. Recycled non-potable water can be safely used. Moisture within the root zone can be maintained at field capacity. Soil type plays less important role in frequency of irrigation. Soil erosion is lessened. Weed growth is lessened.
The benefits include water distribution is highly uniform, controlled by output of each nozzle; labour cost is less than other irrigation methods; 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, reducing the risk of disease.
This system is usually operated at lower pressure than other types of pressurised irrigation, reducing energy costs.
Drip irrigation is used by farms, commercial greenhouses, and residential gardeners. Drip irrigation is adopted extensively in areas of acute water scarcity and especially for crops and trees such as coconuts, containerized landscape trees, grapes, bananas, ber, eggplant, citrus, strawberries, sugarcane, cotton, maize, and tomatoes.
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