Challenges for Pressurized Irrigation in Pakistan
Government of Pakistan is doing right thing by
encouraging farmers to try relatively more efficient pressurized irrigation
systems instead of traditional gravity or flood irrigation. Among the
pressurized systems, special emphasis remains on trickle / drip for point irrigation
that cuts almost 50% demand on existing water demand and increases crop yield
significantly. In this context, just to create demand for the technique and to
adapt the new water application systems, the current planning is to establish
demonstration farms on 1500 acres in Punjab
and 500 acres in each of the remaining three provinces.
In addition to short-term objectives, a strategic interest
in such endeavor appears to be field testing for the sustainability of such pressurized
systems under an environment of medium to heavy soils in arid and semi-arid
region where gravity irrigation has been practiced over centuries. As the
current project is a second or third attempt in the introduction of pressurized
systems, common sense suggests that the new project is based on lessons learned
from the not-so-successful similar attempts made in the recent past. This seems
to be reason that private vendors and companies are being proposed to install
such systems for demonstration in all four provinces.
However, such a paradigm shift in the modality of irrigation
water application is not going to be an easy task. There will be many
challenges of different nature that must be addressed properly for making this
change irreversible.
If the establishment of demonstration sites is limited to a part
of a farm, it may be difficult to fully know the adjustments required for
fitting a pressurized system within a gravity water application environment. Demonstration
sites based on entire farms are essential to learn about challenges that farmers
will have to face in the existing environment of multiple cropping patterns, different
land uses and related cultural practices.
When farms are fully dedicated for crops like vegetables, orchards
or row crops like cotton; drip irrigation fits well. However, the same does not
hold right when seasonal vegetables and row crops follow by say wheat or
fodder. So, the second challenge would be that either new cropping patterns
come into being or some innovative combination of pressurized systems has to be
there to suit the new arising situation.
Even if we have row crops, vegetables or orchards, the
nature of arid and semi-arid region is such that salinity will appear on the
soil surface between rows in no time. To avoid shifting of the salts to adjacent
plants, proper use of rain-water and occasional gravity / flood irrigation may become
a necessity to maintain good soil health. It appears that a system that works
well in sandier or tropical environment may need appropriate adjustments to fit
a medium to heavy soils located in arid and semi-arid regions.
With proper adjustments, drip system should work well for
orchards of mangoes, citrus, apple, guava, etc. However, when inter-cropping is
opted, most citrus growers do, having a sprinkler system in place should help.
In that case, however, challenge is to design a circular water application
system that fits to rectangular fields. In US, some center-pivot systems have
been design to do just that.
For planners and managers, another issue concerns with use
of tube-well and canal water. For tube-well water, drip systems will need
either no or limited filtration arrangement whereas canal water must have to
have silt-free clean water to avoid clogging of drip lines and emitters. On the
other hand, most of the tube-wells in the Indus
valley pump sodic water having high amounts of carbonates and bicarbonates.
Such groundwater creates sodic hazards in medium to heavy soils on one hand;
the deposits of calcium carbonates (lime) could clog emitters on the other
hand. This implies that groundwater has to be treated in most cases and
de-silting of canal water would be necessary for pressurized systems like
sprinklers in general and drip irrigation in particular. Handling treatment
with say sulfuric acid or tackling accumulated silt from different locations
should be another aspect for serious consideration.
Canal irrigation system of the Indus Valley
Of course, next challenge concerns with scenario when we all
switch to pressurized systems to avoid excessive application of water using
surface irrigation. In this case, what kind of remodeling will be needed for
existing water supply systems as well as the new ones to fit efficient but
slow-consumers of water at a farm or field level? Our researchers and planners must
start thinking to devise adjustments to handle the upstream effects of
pressurized irrigation systems. If proper plans are not thought through and
implemented, canals will silt up fast.
Similarly; researchers, managers and planners have to come
up with legal and physical flexibilities of making use of saved water by opting
pressurized systems. Will the head-end farmers be able to sell their saved
water to fellow farmers along the water supply system? This implies to
structural adjustments of water supply systems and nature of water rights in
future.
Another challenge relates to the proposed strategy versus an
alternative one that has been tried in Egypt . In the latter context,
pressurized systems have been encouraged in areas that are beyond the existing canal
commands or generally termed as new areas.
The Egyptian approach seems more practical when compared with issues that are
associated with canals and / tube-well commands as described above. Our
planners and policy-makers should consider following the strategy by declaring
deserts of Thal, Cholistan, Thar and others similar areas for pressurized
irrigation systems only. This should encourage growing high-valued crops and
orchard plants where surface irrigation will cause water logging in these zones
within no time. In the meantime, required conditions can be created to suit the
adaptation of pressurized systems in canal and / tube-well irrigated areas.
In order to make the pressurized systems financially
feasible, there is need to make marketing of agricultural products more
producer-tilted instead of being heavily in favor of middle-men. How can farmers invest in this new technology
when profitability in agriculture is restricted because of this odd marketing environment?
Once profitability is ensured, our policy-makers have to
review the water rates like Abiana and
free-access to groundwater as incentives to switch to efficient water
application systems in agriculture. If seasonal irrigation charge per acre of a
crop in canal commands is less than the rate being charged per hour of a
tube-well in Punjab or free-access to
groundwater with hardly paid power charges say in Balochistan, it would be very
difficult to convince many to this paradigm shift in agriculture.
Asking farmers to leave practices passed on from one
generation to other is tough challenge to be faced. As the farmers are only
familiar with the old ways to apply irrigation, it is asking too much to happen
unless we create conducive environment for the change as stated above and taking
other most urgent steps that include:
- capacity building of farmers on regular basis;
- provision of technical support systems;
- availability of spare parts;
- regular maintenance; and
- Un-interrupted power supply at farm / field levels.
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