Welcome to the Presentation of Seminar Paper

Welcome to the Presentation of Seminar Paper

IMPACTS OF SALINITY ON PADDY PRODUCTION IN COASTAL DISTRICTS OF BANGLADESH: THE ISSUES OF FOOD SECURITYPresented by: Syed Rabiul Alam, Deputy Director(DS) ,DNCRP (under ministry of commerce) , KhulnaSl No.-12, 94th ACAD, BPATC

AbstractIn Bangladesh 1 million hectare of rice lands are currently affected by salinity mainly in the coastal 13 districts and further degradation will have detrimental consequences on food security due to limited land resources.About 53% of the coastal areas are affected by salinity. Agricultural land use in these areas is very poor, which is much lower than countrys average cropping intensity.Salinity causes unfavorable environment and hydrological situation that restrict the normal crop production throughout the year. The dominant crop grown in the saline areas is local transplanted Aman (wet season) rice crop with low yields. Salinity problem received very little attention in the past. Now as it is adversely affecting our staple crop yield , it is posing a serious threat and causing a grave imbalance in our total food security system

The purpose of this paper is to show nature of salinity, constraints of paddy production due to salinity, different measures suggested by researchers to combat this menace and maintain stable paddy production in these affected areas and formulate an unhindered food security system.Based on mainly secondary sources, this study finds that devastating impact of salinity can successfully be minimized, if not fully overcome.Some recommendations have been suggested to tackle the problem of salinity and ensure a total food security system in southern Bangladesh.

INTRODUCTIONThe coastal regions of Bangladesh covers 29,000 sq km or about 20% of the country. On the other hand these coastal areas cover more than 30% of the total cultivable lands of the country.About 53% of the coastal areas are affected by different degrees of salinity. This includes 13 coastal Districts covering 2.5 million ha of land.Of these, nearly one million ha are affected by varying intensities of salinity ,resulting in very poor land utilization and meager amount of paddy production.Rice production is very vital to Bangladesh Economy , as it contributes about 50% of the total agricultural value and employs over 65% of the total agricultural labor force.Rice is grown on about 10.71 million hectares of land in Bangladesh . Rice provides about 71% of the total calories and 51 % of the protein intake of the peoples diet. Rice also accounts for nearly 18 % of the Gross Domestic Product (GDP) of Bangladesh.Rice accounts for 75 % of the total area of agricultural crops, and 93% of the total area planted to cereals. The modern rice varieties cover about 62 % of the total rice areas, which contribute to about 77 % of the total rice production of the country. Salinity causes unfavorable environmental and hydrological situation that restricts the normal paddy production throughout the year.

The dominant crop grown in the saline areas is local transplanted Aman rice crop with low yields. The cropping patterns followed in the coastal areas are mainly Fallow-Fallow-Transplanted Aman rice.As a result food security in Bangladesh is under grave threat , because slight decrease in paddy production will have devastating impact on our staple food supply. At present Bangladesh can barely produce enough rice grain to feed the population.OBJECTIVESThe main objective of this paper is to identify the impact of intrusion of saline water and increase of salinity in coastal belt soil and its adverse effects on paddy production and also to know the real scenario of the saline coastal zone. How these obstacles can be overcome and how a safe, sustainable food security system can be achieved, are other objectives of this assay.Rationale Of The Issue /TopicRice is the principle crop and food of Bangladesh. After independence, keeping pace with population hike, paddy production has increased at least three times. Any shortage of grain production seriously hampers overall food security in our country.Apart from flood, drought and tornado/cyclones , salinity increase in the 13 coastal districts is a grave hindrance to optimum paddy production. If we can minimize the intensity and adverse effects of salinity on rice production in our southern districts , it will at least eliminate a major impediment to optimum crop yield.

A successful food security milieu is very much essential for favorable and harmonious condition of the country and also for good and visible governance.

Therefore, everybody should be aware of the salinity problems in southern regions and be amply prepared for combating this obstacle.

MethodologyThe principal source of information and data of this paper is secondary source, i.e., a few published research papers and articles in news papers . However some of the personal knowledge of the author have been reflected in the paper.Characteristics of Saline SoilSoil reaction values (pH) range from 6.0 to 8.4 ,i.e. most of the soils are moderate to strongly alkaline, the pH values of the surface soils being lower than those of the sub-surface soils.Very low organic matter content in the top soils ranging from less than 1% to 1.5%. This is responsible for poor physical condition of the coastal soils.Salinity range is normally 4 dS/m or above , percentage of exchangeable Na is less than 15 % : the presence of Na+ , Mg++ , Ca++ cations and SO4=, HCO3- , Cl anions are more than enough.

Vital nutrients like N and P are quite lacking in saline soils, but micronutrients, such as Cu and Zn are widespread.

Saline soil contains an excess of soluble salts, especially sodium chloride( NaCl) and sodium sulphate( Na2So4 ).

Due to a number of environmental factors the coastal soils are slightly moderately saline on the surface, and highly saline in sub-surface layers and substrataCauses of salinity in the soilCyclone and tidal surge along the coastal belt.Upstream withdrawal of the Ganges water by the neighboring countries.Widespread brackish water Bagda shrimp cultivation in the southern districts.Irrigation with saline ground water.Salts in water seepage from upslope.

Salts from upward capillary movement of ground water close to the soil surface.Continuous accumulation of salts from tidal flooding.Natural disaster or high water pressure or breakage in the coastal embankment contributes to the intrusion of saline sea water into fresh land.Bangda Shrimp Gher are being established here and there in a very unplanned way, as bagda culture requires saline water , the area under bagda cultivation are gradually been rendered saline and unproductive.

Gradual rise of sea water level due to climatic changes. Bangladesh is highly vulnerable to sea level rise. UNEP (1989) predicted a 1.5 m sea level rise by 2030 which will inundate 16% of total land mass and effect 15 million people, whereas world Bank (2000) predicted a rise of 10 cm, 25 cm and 1 m by the year 2020, 2050 and 2100 respectively which will likely to inundate 2%, 4% and 17.5% of total land mass respectively. Sea level rise has direct influence on salinity intrusion in the exposed and interior coast.Salinity Infested Areas of Bangladesh(1973-2009)Year of Survey of Soil Salinity1973200020098,33,450 ha10,20,750 ha10,56,260 haSoil salinity ClassificationSalinity classDegree of Salinity(EC dS/m)Impact on CropsNon-salineLess than 2Usually on effect on cropsVery slightly saline2-4Very low impact except on extremely salinity sensitive cropsSlightly saline4-8Production of many crops hampered Moderately saline8-12Only salinity resistant varieties surviveStronglysaline12-15Only strongly salinity resistant varieties grow wellExtremely salineMore than15Even strongly salinity-resistant varieties fail to growImpacts of salinity on PaddyPaddy grains fall down immaturely before ripening.Sometimes Rice grains do not mature at all, as a result blank grains ( Chita Dhan ) are produced.Rice grains lose desired taste, flavor or color.Farmers cannot recover the total cost of production because of poor paddy yield and low market price.Salinity causes reduction in panicle number and panicle length of rice and sterility which are the major causes of yield loss.

Salinity-affected Rice Field

Impediments of paddy production in salinity-inflicted coastal Districts Coastal saline soils being silty clay/clay in texture, gets hard on drying, Cracks develop and making tillage operation difficult .Water table too deep to lift irrigation water during seedling planting in rainy season.Saline water remains within one meter from soil surface all the year round.Insufficiency of micronutrients, other than S and K. Acute dearth of N and K. Micronutrients such as Zn and Cu are of very little amount in saline soil.

Soil does not become tillable in time, i.e. moisture content in soil remains decreased.Water becomes stagnant in saline areas and water-logging condition persist .Lack of proper irrigation system due to scarcity of fresh water.Expansion shrimp cultivation in the coastal districts has worsened the salinity condition and there is no or little co-ordination between all sectors.Most of the rice land kept fallow except Aman season due to the extreme presence of salinity of the southwest coastal region.

SOME RECOMMENDATIONSIntroducing salinity resistant paddy varieties such as BRRI Dhan-47 , BBRI Dhan-40 , BBRI Dhan-41 , BRRI Dhan-53, BRRI Dhan-54 and other well-adapted and salinity resistant local varieties. BRRI Dhan- 47 can withstand 12-14 dS/m of salinity while they are tender, and 6 dS/m in their entire lifespan of 152-155 days. The expected yield is 6-7 tons per hectare or around the same as regular rice. Another new salt tolerant rice variety developed by Bangladesh Institute of Nuclear Research , (Binadhan-10) can tolerate up to 12 dS/m of salinity.

Raising of protective embankment in order to prevent intrusion of saline water. In this sector, embankments must be built at least 2-3 meters high above the high tide level during full moon or new moon.Embankments should be quipped with sluice gates at every convenient place to drain out excess water and wash out salt crusted tops during March and April with monsoon rain.Slight variations land relief cause salt accumulation in the raised spots (As a result of capillary rise ).Therefore proper leveling of the ground should be done by the farmers to prevent accumulation of water in the low-lying patches in the paddy fields.

A proper sub-surface drainage system has to be installed to keep the ground water at least one meter below the soil surface. This will help reducing soil salinity by leaching salts. This technology is effective but somewhat expensive.

Enhancing cultivation of well-adapted local T-Aman rice varieties etc .

Keeping lands fallow leads to high salinity in soil due to evaporation of soil moisture. Therefore it is suggested to avoid fallowing of lands during Rabi season. Salt tolerant crops of short life-span(eg.Dhaincha) should be chosen and grown. This will lower profile salinity.

Fertilization of Gypsum and Potash helps to reduce salinity.Monsoon rain water should be harvested in the canal, ditches and blocked rivers to irrigate during dry period.Making high (25-30 cm) ails to store rain to protect saline increase (through capillary rise too) due to drought.Winter is relatively short in the coastal region. So the establishment of Boro season a month earlier might help to avoid higher salinity during April-May.Straw mulching conserves water and reduces capillary rise of saline water and prevents forming saline crust. Soil flashing (washing soil with fresh water) for four times is good for reducing soil salinity from 4 dS/m to 0.49 dS/m During Boro season, one time flashing during reproduction phase is quite useful for the crop.CONCLUSIONSoil salinity is a world -wide problem, Bangladesh being no exception to this phenomenon. Increase in soil salinity will have serious negative impacts on agriculture. Presently practiced rice varieties may not be able to withstand increased salinity. The food production does not seem to have a better future in the event of a climate change. In Bangladesh, rice production may fall by 10% and wheat by 30% by 2050 . Rice being the staple food of the country , decreased paddy production in coastal belt poses a great threat on overall economy. The farmers are becoming poorer , losing their land by leasing out for shrimp cultivation. As a result food security in these areas are greatly threatened. The importance of Shrimp cultivation can not be ignored, because it is a major source of foreign exchange. Therefore there should be a well-coordinated efforts from all quarters to combat this threat.