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Sustaining farm
production under water crisis
By Waqar Abbas
Over the past two to three years, our agriculture is faced
with a serious problem - water shortaage. The question is,
'can we sustain our agriculture under the conditions we are
facing today?' The answer to this, in my opinion, is yes. We
can hopefully do it.
As far as the water availability status is concerned, till
1999 water availability at canal head was 101 MAF but
unfortunately during 2000-2001 it went down to 84 MAF.
(Economic Survey of Pakistan, 2001-2002). Whereas tube well
water which is the second major source of irrigation, took the
other way round and has reached to 55 MAF against 45 MAF till
1999. Presently, we are having about 140 MAF of water whereas
our requirement is 160 MAF. So we are facing a deficit of 20
MAF.
Losses: By having a look at our irrigation system and
percentage of losses at different stages till the time it
reaches the plant, we find that it's a big dilemma that only
22 per cent of the available surface water is used by the
crops. In recent years, irrigation water shortage coupled with
its wastage, has badly hampered agricultural production.
As far as management of the issue, that is water shortage- is
concerned, there could be two types of strategies to overcome
this problem i.e. the long-term and the short-term.
Long-term strategies: Usually 30 per cent of the river water
flows directly into the sea and under present situation, it
amounts to 29 MAF. So by developing new reservoirs, a
considerable amount of this wasted water can be stored and
ultimately the deficit of 20 MAF can be reduced. To minimize
water losses through seepage from canals in brackish water
areas, lining of canal heads and watercourses is needed.
As groundwater is the second important source of irrigation in
our country and farmers augment inadequate canal water
supplies with this source. the scenario is a bit complex. On
the one side, availability of ground water at farm gate has
increased from 3 to 40 per cent during the last four decades
and number of tube wells has reached 500,00 with an annual
increase of 15,000. No doubt, it is very important but on the
other side, its indiscriminate use creates serious problem of
secondary salinization because its quality varies from usable
to hazardous and unfortunately it is often neglected until
considerable effects start to develop.
Ground water recharge for the purpose of augmenting safe
ground water reservoir is very important. Few years back,
withdrawal and recharge were at break-even but presently
withdrawal has reached 55 MAF and recharge has gone down to
around 30 MAF. Under these circumstances, ground water
management and regulation has become very essential to ensure
its rationale use and conservation in terms of quality and
quantity for sustaining agricultural productivity.
In countries like the USA, India, Australia, Jordan,
groundwater rights are regulated by the state. Different
private and public sector bodies are formed to carry out
monitoring, technical evaluations and estimations to keep the
things under control.
Rainwater harvesting measures should be fully exploited in
rain-fed areas by constructing mini-dams and other
infrastructure in barani areas and deserts like Thal,
Cholistan and Balochistan.
The implementation of these long-term strategies is basically
government's responsibility but usually in our socio-economic
set-up, long-term strategies are hardly materialized.
Therefore, it is more advisable that we may concentrate on
short term strategies.
Short-term strategies: These short term strategies have been
focussed to identify management practices to optimize limited
water resources and to co-relate the shortcomings with the
available options which should be affordable and acceptable to
farmers.
On-farm water management: Under the water shortage situation,
we have to increase the water use efficiency which presently
ranges between 35-40 per cent and can be increased by water
course improvement, land-levelling, and eradication of high
water transpiring trees. Water course improvement in addition
to improving water delivery efficiency also has other
advantages like increasing cropping intensity and decreasing
salinity. Similarly, land-levelling considerably improves
water use efficiency and carries multiple advantages such as
about 25 per cent water saving 20-40 per cent increase in
cropping intensity and about 42 per cent reduction in salinity
affected area.
Farmers must know when to irrigate, how much to irrigate and
how to irrigate. In case of water shortage, farmers must
develop water scheduling according to the critical stages of
the particular crop because water stress at certain critical
stage in plant growth causes more injury than at any other
stage. Weather conditions like precipitation, clouds, relative
humidity, wind, low temperatures etc. permit delay in
irrigation which ultimately leads to water saving. Farmers
must take the decisions according to weather conditions, which
are daily announced by PTV and Radio.
Soil moisture status can be judged by digging the soil up to
root zone and examining the moisture status by themselves. Our
farmers are unaware of correlation of different parameters
with quantity of water so usually they over-irrigate the
soils/crops which results into wastage of water as well as
nutrient leaching.
Farmers must go for soil analysis to come to know the physical
and chemical properties of their soils such as texture,
organic matter content etc. which determine the water holding
capacity. Farmers must irrigate according the water
requirements of the crop and should avoid over irrigation. For
example, in rice crop, standing water is not needed through
out the season for high yield but unfortunately in Pakistan it
has been frequently observed that optimum water level of 3 to
4 inches is not followed and sometimes farmers irrigate their
fields up to 12 inches. This practice if truly followed can
save up to 40-45 per cent of water. Understanding of plant
root system can also be helpful in determining the water
quantity. For example shallow rooted crops need light
irrigation as compared to deep rooted crops.
Another important aspect of water management is how to
irrigate because in certain cases due to traditional
irrigation methods, a considerable amount of water is wasted.
For example, if flooding irrigation system is changed into
basin irrigation in orchards, we can save 45-50 per cent of
water. Alternate skip furrow irrigation in sugarcane crop can
also save 35% water in sugarcane.
Crop management: Short duration and low water-requiring
varieties should be evolved by experts and farmers must select
such varieties from the existing ones. Sowing method plays
very important role in water saving. For example, bed-sowing
in cotton need 30-35 per cent less water as compared to flat
sowing. Similarly in sugarcane if row to row distance is
maintained at 3 feet, 25 per cent water can be saved without
yield reduction. In order to increase water use efficiency
weeds management is very important area of concern because
average population of weeds consume about 20-25 per cent water
and may decrease yield as high as 50 per cent.
Cropping scheme has a very important role under water shortage
conditions. Irrigation system is basically supply base but now
farmers have to convert it in to demand base at farm level.
Now they should develop their cropping scheme according to
water availability and demand of the crop.
Cropping pattern: Under the prevailing circumstances, we have
to evaluate any possible change in cropping pattern. We have
to shift from high delta crops to low delta crops which
fulfils the same requirement.
Soil management: Land should be prepared according to the root
system of the crop so that water can easily reach the root
zone. Addition of farm yard manure, green manures etc. improve
water holding capacity of the soil and ultimately reduce water
losses. Generally, farmers try to grow different crops in
problematic soils without reclaiming those, on one side
economically it is not a viable practice and on the other side
a large amount of water is wasted, because in saline soils
considerable amount of applied water is used in balancing the
salts before being used by the plants, whereas, in sodic soils
due to massive and dispersed soil structure much of water
evaporates from soil surface without entering into root zone.
Under the circumstances, such soils should be reclaimed first
so that water wastage is avoided.
Fertilizer management: Balanced fertilizer use maximizes root
extension that ultimately leads to water absorption from low
moisture zones. Potassium, a major plant nutrient, plays a
vital role in 'stomatal' opening and closing and maintains
plant 'turgor' pressure under water shortage conditions.
Proper fertilizer application techniques increase fertilizer
use efficiency and ultimately water use efficiency.
Dry-land agriculture: Dry-land agriculture, which involves
about 20 per cent of the cultivated area. The major limitation
of dry land agriculture is its inadequate and unpredictable
moisture regimes which vary from season to season and year to
year. Rainfall received during monsoon and winter season of
2000-2001 has drastically gone down by about 25 per cent as
compared to last 10 years average. Different strategies if
properly adopted, can help in moisture conservation. Moisture
conservation through deep tillage with the help of 'mould
board' plough is very important because deep tillage enhances
infiltration rate and maximize water storage.
Fertilizer management is another very important aspect in dry
land areas for better water use. Fertilizer use in the dry
land agriculture is minimal; moreover, whenever it is applied,
broadcast method of application makes it a wasteful
proposition. However, placement of fertilizers in the soil at
the time of seeding has shown encouraging results and needs to
be standardized. Conclusion
In fact, severe water constraint is coupled with severe
awareness constraint. After all, and in the final analysis it
is the farmer who spends for and applies the water to his
crop. He should try to use each drop of water effectively i.e.
crop per drop and per square inch as practised in advance
countries and for that matter he needs technical assistance
and guidance to make best use of it.
Therefore, the thrust of extension should now shift from just
number of irrigations and timings to quantity of water and
critical stages, from fertilizer use to balanced fertilizer
use, from crop cultivation to crop management etc. and for
that matter role of print and electronic media should be
exploited to its maximum, so that we can increase our crop
yields mainly from vertical expansion effectively overriding
the limitation of irrigation water supplies.
Courtesy Dawn |
Pakissan.com;
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