URBAN agriculture is the typical requirement of coastal areas of Sindh and Balochistan. The depleting water resources offer no choice but to conserve and judiciously use the scarce available water particularly in areas where the soil is slight to moderately saline.

Pakistan started off with a per capita annual water availability of about 500,000 cubic feet which has dropped to 118,000 cubic feet per person per annum and is expected to drop further to 66,900 cubic feet by 2025 if the present trend persist. A country having per capita water availability of 60,000 cubic feet per person is regarded as a water scarce country, and if no serious effort is made and the present irrigation methods prevail, the country will remain a part of this category.

Adoption of latest technologies in irrigation is vital to sustaining agricultural production and the economic growth as a whole. Today a competition exists among water users of agricultural, industrial and domestic sectors which require better management of water resources. To accomplish the task, it is necessary to adopt modern irrigation methods. One of the most effective irrigation management technologies is the pressurised irrigation technology that saves every drop of water.

Irrigation is often designed to maximise efficiency and minimise the labour and capital requirement of a particular irrigation system and at the same time, maintain a favorable growing environment for the crop. Some managerial input is dependent on the automation, the type system, soil type, topographical variation and management tools which influence managerial decisions.

In recent years, irrigation services have helped farm managers to understand how much water is needed to be applied and how frequently. Irrigation practices such as irrigation before plantation (Rauni), irrigation to ensure emergence of plant and length of time per sprinkler, are managerial inputs which influence water use efficiency over the season.

The engineers of coastal agricultural research station, PARC have demonstrated that the trickle and sprinkler irrigation systems provide controlled irrigation for optimum yield of variety of crops through optimum use of water.

Trickle irrigation is a system where water and fertiliser are applied through sprinkler directly to each plant instead of irrigating the entire area as in surface irrigation systems. For orchards and widely spaced crops, it is accomplished with small diameter laterals running along each plant row. Emitters are attached to the lateral supply water to each plant to meet crop water requirement.

This system needs high initial investment and is energy intensive. But at the same time, it is labour, water and fertiliser efficient. No investment is needed in land leveling, but maintenance requirement of the system is often more expensive than surface irrigation systems. A major economic factor in the use of trickle system is the cost-effective application of fertilisers and pesticides.

This system has been installed for demonstration at fields in costal areas of Sindh and Balochistan and also installed at CARS, PARC in Karachi on two acres area by using one horse power single phase motor, where orchards like guava, ber and chiku are grown.

Cost of trickle irrigation system gets minimised when operated continuously during the critical demand period. In addition to reduced irrigation water requirement and minimisation of return flows, trickle irrigation has other positive advantages like effective water control. Low rate of water application also reduces deep percolation losses.

The plant canopy remains completely dry under the trickle system. It reduces fungus incidence and other pests, which depend on moist environment.

Experiments of trickle irrigation on crops like tomatoes, grapes and sugar beets have shown significant earlier maturation in comparison with other irrigation systems. High temporal soil water level can be maintained with trickle systems. This system results in increasing yield and quality of the crop.

On the other hand, there are some problems with the trickle irrigation system. The most important among them is that small flows through emitters require small openings that have historically been plagued by clogging. With the smaller emitter orifices, more filtering and biological controls are needed. Great advances have been made to rectify this problem but it will always need the attention of the designer.

Similarly like trickle irrigation system, rain gun sprinkler irrigation system is also being applied in coastal areas, and different types of rain guns have been introduced in collaboration with local industries and progressive farmers. No doubt initial cost of installation of this system is high but it is effective and recommended on practically all types of soils, topographic conditions and almost all kind of crops.

Keeping the above facts in view, the micro irrigation system, the modern pressurised irrigation, is the only solution to irrigation water shortage and future food requirements. Time has come to realise the value of every drop of water.