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Soil and Water Salinity, Their Management in Relation to Climate Changes in Coastal Areas of Bangladesh

Mainul Ahsan*
Soil Resource Development Institute, Ministry of Agriculture, Bangladesh

Md. Mizanur Rahman Bhuiyan
Soil Science Discipline, Khulna University, Khulna 9208, Bangladesh

Abstract/ Executive Summary:

Climate change due to global warming and its negative consequence on environment and agro ecosystem is a serious concern of global community of current age. To assess the present soil and water salinity status in coastal areas a soil survey work following standard methods has been completed by Soil Resource Development Institute (SRDI) in 2009. It was observed that out of 2.86 million hectares of coastal and offshore lands about 1.056 million ha of arable lands are affected by varying degrees of salinity. A comparative study of the salt affected area between 1973 to 2009 showed that about 0.223 million ha (26.7%) new land was affected by various degree of salinity during last four decades. It was also observed that about 0.035 million hectares of land (3.5%) new land was affected by various degrees of salinity during last 9 years only (2000-2009). High amount of S and high pH may be the possible causes for P deficiency in coastal areas. Coastal soils are rich in micronutrient elements except Zn. In shrimp cultivated areas flooding with high saline water for a considerable time in each year causing higher soil salinity in all the horizons. A long term soil and water salinity monitoring data of SRDI shows that soil and water salinity between 1991 and 2008 has increased at least 2-10 times. Several common and location specific agricultural constraints have been identified in the field through field investigation/observation and farmer’s interview. Proper fertilizer management practices need to be addressed in coastal saline areas.

Keywords: Climatic change, Coastal area, Soil and water salinity, Nutrient deficiency, Fertilizer management

Location: Coastal Areas of Bangladesh

Start Date: 07-05-2009

End Date:

Program Area: Risk Management in Agriculture

Commodity: Soil salinity, Water salinity

Objectives:

In the recent past, with the changing degree of salinity of some areas due to further intrusion of saline water, normal crop production has become very risky. Crop yields, cropping intensity, production levels and people’s quality of livelihood are much lower than in other parts of the country, which have enjoyed the fruits of modern agriculture technologies- high-yielding varieties, improved fertilizer and water management and improved pest and disease control measures ( BBS, 2001). At the same time food demand in the area is increasing with the steady increase in human population. The present paper analyze the soil and water salinity intensity, extent, constraints and possible soil and water management practices to be followed in coastal areas of Bangladesh.

Methodology:

The Study area: The study area lies between 20^o25' and 23^o20' N latitude and between 88^o25' and 92^o 24' E longitude. The area bound by Kushtia, Chuadanga, Faridpur, Sariatpur, Chandpur and Comilla district on the north, Rangamati, Bandarban districts and Naf river on the east. Bay of Bengal and the Sundarbans on the south and India on the west. Within the study area 93 Upazilas under 18 districts are affected by different degrees of salinity. The total rainfall ranges from 1682 mm to 3627 mm, mostly received during the later part of the summer, increasing from north-west to south-east.

Methods: A special field survey was carried out in the south-western part of the coastal arable land excluding the Sundarbans by soil survey team of SRDI in May, 2009. During field survey different base materials were used. The traverse lines parted 3-4 kilometers from each other. Along the traverse line a total of 2500 soil samples were collected. During field survey soil samples were collected from both outside and inside the polder. Traverse routes followed the catena, from the bank of the river to the centre of the polders. From each catena 6 soil samples (topsoil, subsoil and substratum) from ridges and basins were collected by auger. Surface salt crust was also collected separately. Number of spots varies according to complexity of the soil and shown on Soil Salinity map 2009.

Chemical analysis of soil and water was done following standard methods. On the basis of the soil survey information, a Soil Salinity map (1:2.8) million) is prepared delineating 5 mapping units. Soil salinity boundary of 1973 and 2000 shown too on present Salinity map (1:2.8 million). Coastal boundary is also shown on salinity map. Using the salinity map, present extent of saline soils was calculated cartographically.

Source of Information: Khulna University Studies Special Issue (SESB 2010): 31-42: June, 2010

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Salinity intrusion already affected agro-ecosystem adversely in the coastal region of Bangladesh. As the intensity and degree of salinity are related to change in thermal variability, amount and distribution of rainfall and fresh water discharge from upstream resulted from global warming and some anthropogenic activities will also adversely affect the salinity intrusion scenario. Thus by affecting different livelihood activities and important ecosystem of the country, climate change will impose a grave threat to the economy of Bangladesh.

Knowledge Management: Journal