cost of creating new sources, country can ill afford such a luxury of present irrigation practices that irrigate more of soil and les of crop.
Theoretical potential for micro irrigation according to Tankhiwale is estimated at 176.19 million hectare including 16.89 million hectare of fruits and vegetables and 159.5 million
hectare of oilseeds and field crops. On a conservative assessment the area most suitable for MIS as estimated by the Horticulture Commissioner, MOA, is 27million hectare.
However, despite its established benefits the progress of the system has not been substantial. With government support and aggressive pioneering dedicated and
concerted efforts by the manufacturers; MIS has spread well in a short span of time. But this speedy coverage has slowed down during past few years and unless hard decisions
are taken the prospects of growth of MIS may become gloomy. In that event meeting food security could pose a challenge.
Micro irrigation has fairly extensively covered in a large area in India in the last two decades. A number of new concepts have developed internationally. Also during its
extension several problems have been encountered. It is worth testing these concepts Proper solution of these problems would further expeditious promotion of this efficient
method of water application. Some of the issues may be broadly divided as, criteria of Adoption, Crop related issues, components related problems, Special Applications, Issues
of standardization and: Implementation problems These have been identified and
discussed in the paper.
Researchable Issues
1. High density orchards
Such orchards need an intensive system of inputs and care and also in some case require growth regulators or dwarfing vireos. Normally micro sprinklers have proved
better for citrus because of their spread roots.However in a Valencia orchard inoculated with dwarfing viroid yield per tree was found to be greater for drip and water used was 16
percent of that of micro sprinklers. Inoculation had no effect on growth. Thus response of viriod was better for drip than for micro sprinklers. It is therefore worth examining
whether drip is better both for viriod and water economy.
2. Drip irrigation in Sloping Lands
Feasibility of drip for irrigation in a sloping land not only eliminates the need of constructing costly Bench terraces in sloping lands with shallow soils, has become a
boon for irrigation of orchards. As experienced in Spain and may prove useful here also.
3. Shallow water tables
Drip irrigation in Shallow water tables partially contributes to meet the plant water requirement, more so in fruit trees, as they are relatively deep rooted than most other
crops. Citrus and tomatoes grown under high water tables permitted a substantial cut back of water in Southern Florida without affecting yield thus providing water economy.
This offers a possibility of cutting back irrigation through micro sprinklers, thereby saving water and operational energy cost.
4. Partial Wetting
The trees seem to adapt within one year to partial wetting. It seems that less water stress and yield damage occur in partially wetted trees where the amount of irrigation
water is lowered. On the other hand, partially wetted trees seem to react more favourably to higher water application or fertilization. Most of the differences in fruit yield are caused
by the number of fruits and not by the fruit weight. In studies of citrus trees it has been found that the yield increase ranged from 39 percent for the drip irrigation treatments
which irrigated 5 to 10 percent of the area beneath the tree canopies to 64 percent for two spray jets per tree which irrigated 50.7 percent of the areas beneath the tree
canopies.
5. Sprinkler versus Micro sprinkler
