cultivate crops on the availability of irrigation water
The quantity and quality of water for crops, both
By M. MITHAL JISKANI
Apr 02 - 08, 2001
At present, non availability of sufficient irrigation water
is burning problem all over in Pakistan. Kharif cropping season is near to
start. Therefore, cultivation of drought resistant crops is today's need, for
obtaining optimum crop production and to support economy of the country not so
much, but as much as could be possible.
Pakistan is basically an agricultural country, and has
developed an extensive irrigation system, with barrages and link canals. Its
weather is generally hot (sometimes very hot) in the plains and moderate
(sometimes very cool) in the hilly areas. Agriculture provides food and fibre
for our growing population, as well as fodder for our domestic animals and raw
material for most of our industries. It constitutes the largest sector of the
economy of Pakistan. It accounts for 25% of the gross national product (GDP),
which provides employment to about 54% of the labour force and supports directly
or indirectly, about 70% of the population and contributes to 70% of the foreign
exchange besides meeting the raw material requirement of the domestic industry
to a large extent.
According to "Economy of Pakistan, 1948-68", the
principal assets of Pakistan's agriculture are the fertile soil of the country
as a whole, a generally favourable climate and an elaborate net work of
irrigation. On the other hand, there are some liabilities which hamper growth
and development. These are low productivity land caused by water-logging,
salinity and soil erosion; primitive methods of cultivation; small and
fragmented holdings; conservation and illiteracy of the cultivators which make
extension work difficult; low income of farmers making investment for adopting
improved agricultural practices difficult; land tenure problems; poor marketing
facilities, inadequate transport, communication and market intelligence; and
Except and or including above discussed yesterday's
constraints, non availability of sufficient irrigation water is today's burning
problem at all over Pakistan. No doubt, water is the most important plant
nutrient and constitutes the greater part of plant weight, hence is absolutely
essential for plant life. Apparently even dry plants contain an appreciable
amount of water because water is basic need and works as the nutrient solvent.
In fact, plants use more water than any other substance they absorb, therefore
the water in sufficient quantity is vital necessity for all plants. The function
of soil moisture in plant growth is very important. When soil moisture is not
enough, drought condition prevails leading to ultimate death of the plant. The
availability of nutrient is controlled by the moisture content of the soil. On
the other hand, it is also true that excessive water quantity in the soil
inhibits plant growth and makes drainage essential. Excessive moisture reduced
the supply of oxygen, which actually needed for respiratory system of the plant.
While excessive moisture may also delay flowering and can lead to poor pod/fruit
formation and filling as well as reduce grain/seed quality.
The agriculture of Pakistan is characterised by two main
cropping seasons, namely, the Kharif (summer crops) from April to September; and
Rabi (winter crops) from October to March. Wheat is the main crop of Rabi
season, while rice, maize, sugarcane and cotton are considered the major crops
of Kharif. Mono cropping, sequence cropping, mixed cropping, inter-cropping and
relay cropping systems are practiced by growers (farmers), especially those with
small holdings, to maximise crop production per unit area. The cropping pattern
is largely determined by water availability and the climatic conditions as
adaptation of crops. However, present situation of irrigation water is widely
being reported daily through TV, Radio as well as Print media. A lot of research
has been carried out by various research workers, on different crops, for their
requirements of irrigation water. The results so far achieved, according to
their critical growth stages as well as cultivation season, are being summarised
here under, as per recommendations by Bhatti and Soomro (Ref. Agricultural
inputs and field crop production in Sindh, ARS, Hyderabad, 1996. Now it is upto
the growers that what they want to cultivate and how they would try to fulfil
the irrigation water requirements of their crops.
Rice: Rice is one of the leading cash and foreign
exchange earning food crops of the world, including Pakistan. It requires a
constant and plentiful supply of irrigation water. It needs 46 acre inches as
soaking dose 4-6 days before transplanting, 1-2 acre inches at the time of
transplanting and 3-4 acre inches 7-10 days after transplanting to maturity of
the crop. The reproductive stages from penicle initiation to flowering and grain
formation are the critical stages. Any stress at this stage will affect the
yield and grain quality. However, rice requires over all 60-70 acre inches
irrigation water on the basis of varieties.
Maize: Maize is also one of the cereal crops. It is
very efficient water user. It needs large quantities of irrigation water for
high yield, because drought conditions lead to lower yields and lower quality
grains. Maize requires 6-8 irrigations. First irrigation 3-4 weeks after sowing,
remaining may be given at 10-15 days interval. The grain formation is critical
growth stage. It is not important grain crop in Sindh, but is grown mostly as
fodder crop and very rare as for grain.
Sorghum (Jowar): The major area of sorghum in Pakistan
lies in Punjab, but the yield per hectare is higher in Sindh. The sorghum plants
are drought resistant, but 3-4 irrigations (30-35,50-60 and 70- 80 days after
sowing) are compulsory for better yield.
Millet (Bajra): The area under millet crop is highly
variable, because it is dependent on the amount and time of the rainfall. It is
mostly confined to the desert and mountain (Thar, Cholistan and Kohistan) area.
3-4 irrigations are sufficient for better yield, as recommended for sorghum.
Mungbean (Green gram): It does not require much
irrigation due to short duration and drought tolerant crop. However, 3-4
irrigations are sufficient for getting good yield. Flowering and seed
development stages are very critical.
Mash (Black gram): Irrigation requirements are same as
Arhar (Pigeonpea or Red gram): Same as discussed for Mungbean.
Cowpea: This crop is grown as pulse, vegetable, fodder
and green manure crop, hence is of economic importance, especially in Sindh.
Irrigation requirements are same as of Mungbean crop.
Cotton: Cotton is alone fibre crop of Pakistan. It is
also most important cash and foreign exchange earning crop. It requires 7-8
irrigations (at least 80 cm) to get an acceptable yield. The first irrigation is
to be given 35-40 days after sowing (DAS) and subsequent irrigations should be
applied at 15 days interval. The most critical stages for irrigation are early
flowering to first boll opening and maturity.
Sugarcane: Sugarcane is also one of the major crops.
The highest acreage is in Punjab but yield is higher in Sindh. The crop requires
30-33 irrigations at 15 days interval during winter and weekly in summer (a
total of 96 acre inches).
Sunflower: Sunflower has gained higher popularity and
acreage, among the new oilseed crops introduced for boosting edible oil
production. The important features of this crop are short growing period, high
yield potential and wide range of growing season viz. autumn, spring and winter.
It fits well in different cropping patterns, low irrigation water requirements,
wide adaptability to soil and moisture conditions. Its seed contains high oil
(over 40%) of good edible quality and meal of good quality free from toxic
compounds. 3 irrigations are necessary. The 1st irrigation should be given 30-35
DAS, 2nd at start of flowering and 3rd just after petal fall.
Soybean: It requires 5-7 irrigations from sowing to
maturity. Irrigation at pod filling stage is very necessary, drought at this
stage will reduce yield drastically.
Groundnut (Peanut): This crop requires 30 acre inches
during 5-7 irrigations. The first irrigation should be given 25-30 DAS and
subsequent at 15-20 days intervals. The critical stage is seed development.
Sesame: The sesame is cultivated throughout Pakistan
as irrigated as well as un-irrigated crop. It requires 3-4 (21 acre inches)
irrigation at 30 days interval.
Caster: Caster is grown under arid conditions, mostly
as rainfed crop. Under irrigated conditions, it needs 5-7 (20 acre inches)
irrigation at 30 days interval.
Guar (Cluster bean): It is a very important drought
resistant Kharif legume of Barani and irrigated areas. However, if irrigation is
available, then 20-25 cm per hectare, in the course of 2-3 irrigations increase
Moth: Moth is also important drought tolerant crop,
cultivated as rainfed. Irrigated crop requires 2-4 irrigations.
Sesbania (Janter or Danicha): This crop is widely
grown in all over Pakistan as main Kharif fodder and as green manure crop. It
adds about 80 kg/ha nitrogen in the soil, therefore also used as rotation crop
for maintaining the soil fertility. This crop requires 4-6 irrigations. First
2-3 irrigations at weekly and following should be applied fortnightly.
Wheat: Wheat is a staple food of more than one third
of the world population. The major area in Pakistan lies in Punjab, but the
yield per hectare is slightly higher in Sindh. 5-6 irrigations (21 acre inches)
are sufficient, for normal wheat crop, under optimum soil conditions. First
irrigation should be given 3-4 weeks after sowing. Out of all stages, crown root
initiation (CRI) is the most important stage for irrigation, in view of nutrient
availability and root development. Other critical stages are tillering, heading,
milky and dough 21, 50, 80 and 100 days after sowing (DAS) respectively.
Barley: Barley is drought tolerant crop. It does not
require much irrigation. However, 3-4 irrigations are recommended for maximum
yield per unit area. First irrigation is to be given at 35 DAS. The irrigation
at actively tillering increases the yield.
Gram (Chickpea): About 81% of gram area in Pakistan
lies in Punjab followed by NWFP and Sindh, but the yield is highest in Sindh. No
irrigation is required if planted after rice as Dobari crop. In case of
irrigated crop, only one irrigation is required at pre-flowering stage. Heavy
pre-sowing irrigation is better than light pre-sowing irrigation.
Lentil (Masoor): One irrigation at pre-flowering is
adequate, but in light soil, it requires two irrigations. However, no irrigation
is required for Dobari or Bosi crop.
Grasspea (Matter): Two irrigations are sufficient
under irrigated conditions, but no irrigation is required for Dobari or Bosi
Rapeseed and Mustard: 3-4 irrigations may be given to
Toria and Sarsoon, 1-2 irrigations to Jambho or Taramira at 25-30 days
intervals. Seed development stage is critical for irrigation. No irrigation is
required for Dobari or Bosi crop.
Safflower: It is sensitive to heavy irrigations,
especially in later growth stages. However, 56 irrigations are required under
Linseed: 4-5 irrigations are enough. First irrigation
30 DAS and subsequent doses at 20-25 days intervals should be given. No
irrigation is required, when it is grown as Dobari crop.
Lucerne (Alfalfa): Lucerne is very important
leguminous fodder, grown as a subsequent crop. 2 light irrigations in a week
after sowing are helpful. It requires 10-15 irrigations in year, with an
interval of 7-10 days during summer and 15-20 days in winter months. The yields
are decreased with delay in irrigations.
Berseem: First 2 irrigations should be light and
within a week. The following irrigations should be given at 10-15 days
Senji: It is one of the fodder crops, needs 2-3
irrigations during entire cropping period.
It should be kept in mind that water in larger quantities, as
well as unfit water of different types must not be used for irrigation purpose.
Only the water, that may be fit for the purpose, should be used in required
quantity with suitable methods and time. Otherwise any problem in the crop as
well as to the soil may occur due to its poor quality, pollution or so.
*Assistant Professor (Plant Pathology); Sindh
Agriculture University, Tandojam