Sindh is the third largest province of Pakistan. The total land area of Sindh, which lies between 23 and 29 degrees north latitude and 67 and 71 degrees east longitude, is 14.1 million hectares (or 34.84 million acres).
This represents 18% of the total geographical area of Pakistan, which is 79.61 mha. Out of this, nearly 39% or 5.45 million hectare (or 13.45 million acre) is cultivable. About 9.9% is culture-able waste and 0.57 mha or 4.8% is under forestry.
The remaining 8.65 mha or 44.2 percent is not available for cultivation. Again of the total cultivated areas of 5.45 million hectares, nearly 57% are currently fallow, which is the highest in the country and reflects on the poor water availability, mismanagement and ill-practices of the irrigation systems in the province.
It is stated that out of the salt free, ie cultivated or cropped areas, which are 3.079 million hectares or 57%, about 2.321 million hectares (or 42%) are salt-affected.
This includes 1.342 million hectares (or 57%) of highly saline 0.673 million hectares (or 29%) of permeable saline-sodic.
Similarly, 0.277 million hectares (or 12%) of impermeable saline-sodic and 0,028 million hectares (or 1.2%) of sodic soils. The menace of salinity is towards the increasing end.
It is estimated that the fertile land of Pakistan is becoming saline at the rate of 40,000 hectares annually.
This shows that 109 hectares of our land is converted into saline daily. This situation is very alarming, particularly in Sindh, because, more lands are becoming saline in Sindh than in the other provinces.
The climate of Sindh is arid and hot. On an average, the region receives the maximum rainfall of 170-200 mm. During summer the temperature goes to 53°C. The coldest season is from December to February. July to mid-September is the monsoon season.
In Sindh, in the salt free areas of electrical conductivity (EC) of less than 4 dS/m, where salts are not visible on the surface, all kind of crops can be grown without any difficulty.
The soils which are slightly saline have an EC of between 4-8 dS/m, where salts are slightly visible at the surface, and under such conditions growth is uneven or patchy.
The soils which are moderately saline have an EC in between 8-15 dS/m, the salts are fairly visible and growth very patchy.
The soils which are strongly saline, have an EC of more than 15 dS/m and the salts are widely spread, growth is almost nil or very poor.
In the main Indus basin alongside the river, the soil is silty and the sandy loam or loamy. Outside this area, soils are calcareous, loamy and clay with weak structure and good porosity.
The pH is generally in the range of 7.8 to 8.2 and organic matter is about 0.3 to 0.6% and the N content varies from 0.01 to 0.07%, which seems to be very low. It has been observed with concern, that since the last couple of decades, the cropped areas are declining in Sindh.
Statistics reveal that since 1980, the total cropped areas of other provinces ie Punjab, NWFP and Balochistan have increased by 9.83, 5.01 and 7.56%, respectively. But such areas in Sindh have decreased by about 2.31%, and as far as irrigated areas are concerned, data shows that Punjab, NWFP and Balochistan have increased by 15.8, 13.1, and 22.45%, respectively, whereas Sindh has lost about 10.2% during the period 1980-98.
Area irrigated in Sindh is 2.85 mha, of this 2.27 mha is irrigated by canals, 0.13 mha by tube wells and the rest by ordinary wells or other sources.
The river Indus has a very high variability in its flow regime. Based on 50 years inflow data, it is estimated that the Indus basin has a mean annual surface water availability of about 141 MAF.
Of this, 23.0 MAF (or 16%) is available during the six Rabi months from October to March, 44.5 MAF (31%) during first three Kharif months from April to June and 73.36 MAF (52.1%) during the last three Kharif months from July to September.
It shows that 42% of the total annual main flow is available during the two months, July and August.
In both the periods of severity, of low and extremes flows, Sindh is the major sufferer, being at the tail end of the irrigation system. Both these extreme situations are responsible for the development of the twin menace of water logging and salinity.
The extent of water logging and salinity is more pronounced in Sindh than elsewhere in Pakistan.
About 70 percent of the cultivable area in Pakistan, that is vulnerable to water logging and salinity, is in Sindh.
As a downstream region, Sindh is at the receiving end of 80 millions tons of salt together with 120 million cubic meters of salts annually from the up-stream regions of its course. Being to the region of the Arabian Sea also contributes to the salinity of ground water.
Out of the total cultivable command area of 13.45 million acres in the Sindh, only 1.85 million acres is under the treatment of fresh ground water.
In such an environment, water logging, arising from insufficient management of canal irrigation and inadequate drainage practices, aggravates the salinity problem, by raising the ground water table.
In Sindh, the areas cultivated by canals declined from 6.6 million acres to 5.3 million acres, during the year 1997-98.
Salinity and water logging has affected the Sindh Province. More than 57 percent of the cultivable land of Sindh is under water logging, whereas 41 percent is under the influence of salinity.
The Eucalyptus plant may tolerate salinity upto 10 mS/cm, but its cultivation has many advantages and disadvantages.
This plant generally absorbs a high quantity of saline water through its root and thus helps in reducing the salt from that land.
This makes the soil fertile, for growing other economical plants. Field crops are grown by man for food, fibre and fodder for animals.
The land area available to him is limited, thus there is a need to grow more from each piece of land available to him, to feed the ever increasing population.
Much of the land, in Sindh, is deteriorating very fast due to the duel menace of water logging and salinity.
Research scientists in Sindh have made definite advance during the last three decades. Many new improved varieties, with higher yields and quality, have been developed.
Chemical control of insect, pests diseases have proved useful in reducing losses due to their attack.
However, there is a need to apply efficient production technology to obtain sufficient a yield of crops in order to improve the growth of crops in salt-affected lands.
In Sindh, fields are irrigated through the help of three barrages ie Sukkur, Guddu and Kotri.
The main crops, grown in Sindh, are of wheat, rice, bajra, maize, jowar, barley, gram, lentil, mung, guar, cotton, sugarcane, sunflower, safflower, soybean, rape and mustard, groundnut (peanut), linseed, sesamum, castor, chillies, matter, fodder, potato, cowpea, red gram (arhar), clover, berseem, date palm, carrot, onion and tomato.
The soil needs management practices and fertilisation, Addition of farm yard manure, green manure through legume crops is necessary to improve soil conditions.
Along with manure, N,P,K fertilisers are useful in increasing crop productivity, by improving the physical and chemical properties of the soil.
Irrigation is also essential for the growth of the crops. Application of water to the soil for the purpose of supplying moisture is essential for plant growth. Crop water use is usually expressed in acre inches.
An acre inch is the amount of water required to cover one acre of land with one inch of water.
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