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Final Report 1. Title of the research project: EFFECT OF SALINITY ON PHYSICAL AND CHEMICAL PROPERTIES OF SOILS OF KHULNA REGION 2. University where research is being carried out: Soil Science Discipline Khulna University, Khulna-9208 3. (a) Name of the Project Director: Dr. Mizanur Rahman Bhuiyan (b) Address: Soil Science Discipline, Khulna University, Khulna-9208 (c) Academic Qualification of Project Director: M.Sc. (Soil Science), Ph. D. (d) Research Assistant: Ms. Roxana Ahmed, M.Sc. 4. Date of Initiation and duration of the Project: 01 November 2005 & 1(one) Year 5. (a) Total Amount Sanctioned: Taka 80,000/- (b) Amount Received: Taka (c) Amount Spent: Taka 6. Introduction: Salinity is one of the most important problems of coastal belt of Bangladesh. Saline

soils, as they contain high concentration of soluble salts are not very suitable for normal

agricultural practices. The coastal offshore area of Bangladesh includes tidal, estuarine and

meander river floodplains. The tidal floodplain land occurs mainly in the south of the Ganges

river floodplain and also on different parts of Chittagong coastal areas. The Ganges tidal

floodplain constitutes about 49% of the coastal areas (Karim et al., 1982). The total amount

of sediment that Bay of Bengal receives is about 1.7 x 109 ton per year. When the deposited

alluvium comes to the contact of sea water it becomes saline. The degree of salinity varies

mainly with season and intensity of tidal flooding (SRDI, 2003). At present total extent of

salt affected soils in Bangladesh is about 10, 20,750 ha. In Khulna, Bagerhat and Satkhira

district the extent of saline soil is about 4,17,460 ha in 2000 which is about 40% of total

saline soil. The recent survey has indicated that the total saline soil of Bangladesh is

increasing. According to SRDI, 2003 the total extent of saline soil was 8,33,450 ha in 1973

and while in 2000 it becomes 10,20,750 ha. Over the last three decades total salt affected

areas increase by 22.47% which is very much alarming. Recent satellite imagery shows that

the non-saline soils of coastal and other regions are gradually becoming saline. This may be

due to withdrawal of water by India during dry season, introduction of brackish water for

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shrimp cultivation, faulty management of sluice gates, regular saline tidal water flooding in

unpoldered area, capillary upward movement of soluble salts due to presence of high saline

ground water table at shallow depth (SRDI, 2003). The salinity has very significant effect on

physical, chemical and biological characteristics of soil. The hydraulic properties, the

aggregate stability, soil strength and soil aeration are influenced by soil salinity. The changes

in soil physical behavior are controlled by salt characteristics of the saline soil (Kaur, 1994).

Soil salinity also affects nutrient availability and microbial transformations in soil (Swarup,

1994). The existing reports on soil salinity mainly deals with the chemical properties of salt

affected soil and little light has been put forward to evaluate physical properties and to

determine the changes in microbial processes in saline soils. Apart from the evaluating the

physical and chemical properties of saline soil it is also very important to evaluate the effect

of salt water intrusion in non saline soils because the soil salinity has been expanding its

claws over Bangladesh. The intrusion of salt water will change the aggregate stability of soil

by enhancing the rate of slaking. The rate of slaking is controlled by salt characteristics, salt

concentration and exchangeable sodium percentage of soil (Rost and Rowles, 1941). The

rapid slaking can seal the pores and decrease hydraulic conductivity, water retention

characteristics and aeration capacity of soil. It is inevitable to determine the rate of change in

nutrient availability and microbial processes due to the increase in salt concentration. This

information will help to adopt best measures for managing the saline soils.

The aim of this research work is to investigate the effect of saline water application on

physical and chemical properties of soils.

7. Materials and Methods:

7.1. Experimental Design: A laboratory incubation experiment was carried out to assess the effect of salt water

intrusion in non saline soils. Two non saline soils were selected from Ganges Meander

floodplain of Khulna division. A calcareous (C) and a non calcareous (NC) soil of Silt loam

texture were selected. Saline water (13 dSm-1) was collected from the river at Shamnagar,

Satkhira district. The salinity treatments were 0, 6.5 and 13 dSm-1 in both soils. Analyses of

treatment water are presented in Table 1. Each salinity treatment was replicated three times.

The treated soils were then incubated in laboratory condition for 7, 15, 30, 60 and 120 days.

The water content of the incubated samples was maintained at field capacity. The symbols

used in the experiment were presented in Table 2. Soil pH, EC, available N, P, K, S, Ca and

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Mg were determined after each sampling. The changes in micro-aggregation were analyzed

prior and after the completion of incubation.

Table 1. Analyses of treatment water

Salinity

pH P S04

2- K+ Ca2+ Na+ Cl- HCO3-

(dS m-1) (g g-1) (cmol(+)kg-1)

0 7.97 0.03 0.00 0.00 0.00 0.00 0.00

0.00

6.5 8.3 0.03 7.13 0.54 1.25 4.18 50.00

244.00

13 8.44 0.05 18.15 1.38 3.20 10.56 67.50

305.00

Table 2. Symbols used in the experiment

Salinity

(dS m-1)

Soils

Calcareous soil Non calcareous soil

0 C0 NC0

6.5 C6.5 NC6.5

13 C13 NC13

7.2. Methods of Analyses 7.2.1. Particle size analysis: The particle size analysis of the soils was carried out by

combination of sieving and hydrometer method as described by Gee and Bauder (1986).

7.2.2. Microaggregate analysis: Soil structure was evaluated by microaggregate

analysis of the soils following the method Kachinskii (1965) with the exception that

hydrometer was used to determine the particle size distribution instead of pipette method.

The state of aggregation and dispersion factor were calculated by the using the following

equations (Baver and Rhoades, 1932)

State of aggregation = ba Dispersion factor = 100

yx

4

Where a = percentage of aggregates larger than a specified size in microaggregate analysis, b

= percentage of particles larger than a specified size in particle size analysis, x = percentage

of clay in microaggregate analysis and y = percentage of clay in particle size analysis.

7.2.3. Soil pH: Soil pH (2:1) was determined electrochemically with the help of glass

electrode pH meter as suggested by Jackson (1973).

7.2.4. EC: The electrical conductivity of the soil was measured at a soil water ratio of

1:1 by EC meter (USDA, 2004).

7.2.5. Available P: After extraction of soil sample with 0.5M NaHCO3 (pH 8.5)

solution (Olsen et al., 1954) the concentration of P was determined by ascorbic acid blue

color method (Murphy and Riley, 1962).

7.2.6. Available S: After extraction of soil with 500 ppm of P from Ca-phosphate

(Fox et al., 1964) the concentration was determined by turbidity method as described by

Hunt, 1980.

7.2.7. Water Soluble and Exchangeable Na+ and K+: Exchangeable Na+ and K+ was

extracted with 1N NH4OAc solution (pH 7.0) as described by piper (1950) and Jackson

(1973) and then analyzed by Flame Photometer. Water soluble sodium and potassium was

determined after extraction with distilled water.

7.2.8. Water Soluble and Exchangeable Ca2+ and Mg2+: Exchangeable Ca2+and

Mg2+ was extracted with 1N NH4OAc solution (pH 7.0) as described by piper (1950) and

Jackson (1973) and then analyzed by atomic adsorption spectrophotometer.

7.2.9. Chloride: Water soluble chloride was determined by titration with silver nitrate

as described by Reitemeier (1943).

7.2.10. Bicarbonate: Bicarbonate was determined by titration with sulfuric acid as

described by Reitemeier (1943).

7.3. Statistical Analysis: The data was analyzed statistically by MINITAB (release 13.20). 8. Results:

8.1. Particle size and Microaggregate analysis: The percentages of sand, silt and clay in calcareous soil were 13.05, 55.0 and 31.95, respectively. The percentages of soil separates slightly varied in non-calcareous soil where

the percentages of sand, silt and clay were 13.05, 52.5 and 34.45, respectively. State of

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aggregation slightly increased due to saline water application whereas dispersion factor

showed slight variation (Fig. 1-2).

8.2. Soil pH: Soil pH was increased during 15 days incubation. After 15days pH of the soil tended to decrease slightly in both soils. The change of soil pH was higher in higher salinity

treatments in both calcareous and non-calcareous soils (Fig. 3). In the calcareous soil the

change of pH was higher than the changes in non-calcareous soil. The effect of saline water

application was significant in calcareous (p

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15 days of incubation in all salinity treatments except 6.5 dS m-1 salinity treatment in non-

calcareous soil. This increment was followed by another sharp decrease after 30 days

incubation with few exceptions. However, after 60 days the S concentration tended to be

leveled off. Initially changes in S concentration due to salinity treatment was higher in non-

calcareous except in 6.5 dS m-1 treatment but in later stage S concentration was higher in

calcareous soil in 13 dS m-1 treatment. The effect of salinity treatment was statistically

significant (p

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The increase in Mg concentration was higher in higher salinity treatment in both calcareous

and non-calcareous soils.

8.9. Available Na: Available Na content was increased in both calcareous and non-calcareous soils with the

salinity treatments (Fig. 10). The increase in Na concentration was lowest in 0 dSm-1 salinity

treatment and highest in 13 dSm-1salinity treatment. The change in Na concentration showed

an increasing trend during15 days incubation. The concentration of Na exhibited a decreasing

trend during 60 days incubation. After 60 days Na concentration tended to be leveled off. The

changes in Na concentration were higher in non-calcareous soil than its calcareous

counterpart. The statistical analyses revealed that the effect of salinity treatment on Na

concentration was significant (p

8

0

1

2

3

4

5

6

EC0 EC6.5 EC13

Salinity Treatments

Stat

e of

Agg

rega

tion

C NC

Fig. 1. Effect of salinity treatments on state of aggregation

0510152025303540

EC0 EC6.5 EC13

Salinity Treatments

Dis

pers

ion

Fact

or

C NC

Fig. 2. Effect of salinity treatments on Dispersion Factor

9

6.8

77.2

7.47.6

7.88

8.28.4

8.68.8

9

0 7 15 30 60 120

Time Interval (Days)

pH

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 3. Effect of salinity treatments on Soil pH

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 7 15 30 60 120

Time Interval (Days)

EC (d

S/m

)

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 4. Effect of salinity treatments on Soil EC

10

0

5

10

15

20

25

30

0 7 15 30 60 120

Time Interval (Days)

Ava

ilabl

e P

(g

g)

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 5. Effect of salinity treatments on available P

050100150200250300350400450500

0 7 15 30 60 120

Time Interval (Days)

Ava

ilabl

e S

(g

g)

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 6. Effect of salinity treatments on available S

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 7 15 30 60 120

Time Interval (Days)

Avai

labl

e K

Cm

ol(+

) Kg

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 7. Effect of salinity treatments on available K

051015202530354045

0 7 15 30 60 120

Time Interval (Days)

Ava

ilabl

e C

a C

mol

(+) K

g

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 8. Effect of salinity treatments on available Ca

12

0

2

4

6

8

10

12

14

0 7 15 30 60 120

Time Interval (Days)

Ava

ilabl

e M

g C

mol

(+) K

g

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 9. Effect of salinity treatments on available Mg

0

1

2

3

4

5

6

7

0 7 15 30 60 120

Time Interval (Days)

Ava

ilabl

e N

a C

mol

(+) K

g

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 10. Effect of salinity treatments on available Na

13

05101520253035404550

0 7 15 30 60 120

Time Interval (Days)

Ava

ilabl

e C

l Cm

ol(+

) Kg

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 11. Effect of salinity treatments on Cl concentration

0

5

10

15

20

25

30

35

0 7 15 30 60 120

Time Interval (Days)

Ava

ilabl

e H

CO

3 C

mol

(+) K

g

C0 C6.5 C13 NC0 NC6.5 NC13

Fig. 12. Effect of salinity treatments on HCO3-concentration

9. Discussion: Soil salinity is one of the most critical aspects that may influence the future agriculture of

Bangladesh in future. So, the short and long term effect of soil salinity need to be

investigated. In the present work short term effect of saline water application was studied.

Saline water application increased EC of the soil. As the studied soils were non-saline

addition of highly saline water (13 dSm-1) did not increase EC of soil greater than 2 dSm-1.

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This increase was greater in the later stage of incubation may be because of dissolution of

soluble salts in soil. Several investigators also reported that addition of saline water during

irrigation markedly increase soil salinity (Goorahoo et al., 2003 & Moreno et al., 2001).

Increase in soil salinity has direct positive and negative impact on soil aggregate stability.

Soil salinity associated with high exchangeable sodium percentage (ESP) and sodium

adsorption ratio (SAR) is responsible for clay swelling and dispersion (Halliwell et al. 2001

& Warrence et al., 2002). Whereas other investigators concluded that presence of dissolve

salt of Ca and Mg increase the stability of aggregates (Warrence et al., 2002). In the present

investigation increase in state of aggregation was reported. Reaction of soil and nutrient

dynamics is also affected by level of soil salinity. In the present work it was observed that pH

and EC were negatively correlated both calcareous and non-calcareous soils. Al-Busaidi and

Cookson (2003) reported that readings from the pH electrode from non-saline soils tended to

fluctuate more than when readings were taken from saline soils. However, pH readings from saline soils in different electrolytes also fluctuated but not to the same extent as in non-saline soils. Electrolytes appeared to suppress fluctuations in pH readings, probably due to, both, reducing the liquid junction effect (especially in water) and minimizing alkaline errors. The reduction in fluctuation between pH values in non-saline and saline soils supports the use of electrolytes especially in non-saline soils. However, Gupta et al. (1989) argued that sodium ions react in calcareous soils to

form sodium carbonate and bicarbonate, which by hydrolyzing at pH values more than of 8.8, leads to

a direct relationship between soil salinity and pH. Soil pH, EC has direct influence on Ca, P and S

dynamics in calcareous and non-calcareous soils. CaCO3 plays a pivotal role in P dynamics in

calcareous soil. In the present investigation P availability in soils varied with cyclic variation in Ca

availability. In calcareous soil addition of saline water increased the Ca concentration in soil solution

and thus leaded to precipitation of CaCO3 according to the theory of common ion effect. Thus Ca

concentration in soil reduced and P availability increased. But with time of incubation Ca

concentration increased. This may be due to dissolution of CaCO3. The dissolution of precipitated

CaCO3 can occur if the value of equilibrium constant of the reaction of CaCO3 precipitation is less

than 10-10 (Al-Busaidi and Cookson, 2003). This precipitation and dissolution may repeat in the

incubation period and controlled P concentration in soil. The bicarbonate ion produced during

dissolution of CaCO3 may react with Na and Mg of soil solution and thus caused to reduce bicarbonte

continuously during incubation. The initial increase in SO42- may be due to the addition of saline

water. The subsequent decrease may due to co-precipitation with CaCO3 (Al-Busaidi and Cookson,

2003). Potassium availability decreased with time in various salinity treatments in both the soils

indicates the K fixation by 2:1 type minerals and may be favored by the increase in soil moisture

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(Sparks and Huang, 1985). Although it was not observed in the present research, other scientists

reported that K decreased with increasing salinity in different soils (Bang, 2005).

10. Progress made during the period: The project work has been completed.

11. Conclusion/ Observation: The short term effect of saline water application did not increase the soil salinity greatly.

Aggregation state improved due to addition of saline water. The different nutrients behaves

quite differently in different salinity levls. The relationship between pH-EC, and precipitation

and dissolution of calcium carbonte controlled most nutrient availability in soil. Future

reseach should be directed to pH-EC relationship in calcareous and non-calcareous soil. The

role of calcium carbonte in controlling soil reactions in calcareous soils of Bangladesh not yet

well understood. The study of short and long term effect of saline water or brackish water on

soil can supply aliment to the agricutural policy makers for desiging effective irrigation

program for winter crops in forthcomming decade. A scrupolous research is essential for

finding out irrigation alternative in this field.

12. References:

Al-Busaidi, A.S., and P. Cookson. 2003. SalinitypH Relationships in Calcareous Soils. Agricultural and Marine Sciences 8(1):41-46. Bang, J. 2005. Characterization of soil spatial variability for site specific management using soil electrical conductivity and other remotely sensed data. PhD. Dissertation, Department of Soil Science, North Carolina State University, USA.

Baver, L.D. and H.F. Rhoades.1932. Soil aggregate analysis as an aid in the study of soil structure. J. Am. Soc. Agron. 24: 920-921. Fox, R.L., R.A. Olsen and H.F. Rhoades. 1964. Evaluating the sulfur status of soils by plants and soil tests. Soil. Sci. Soc. Am. Proc. 28:243-246 Gee, G.W. and J.W. Bauder. 1986. Particle size analysis. In: A. Klute (ed.) Methods of Soil Analysis. Part-1, 2nd ed. Agron.9. ASA, Madison,WI. Pp: 383-411.

Goorahoo D., S. Benes, D. Adhikari and J. Bartram. 2003. Soil characterization of fields irrigated with recycled saline drainage waters. Proceedings of the national meeting of the Irrigation Association of America (IAA). Nov. 18-20th, San Diego, CA. 12 pages.

Gupta, R.K., R.R. Singh, and I.P. Abrol. 1989. Influence of simultaneous changes in sodicity and pH on the hydraulic conductivity of an alkali soil under rice culture. Soil Science 147(1): 28-33. Halliwell, D.J., Barlow K.M. and Nash D.M. 2001. A review of the effects of wastewater sodium on soil properties and their implications for irrigation systems. Australian Journal of Soil Research. 39:1259-1267. Hunt, J. 1980. Determination of total sulfur in small amount of plant material. Analyst.

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105:83-85.

Jackson, M.L. 1973. Soil Chemical analysis. Prentice Hall of India Pvt. Ltd. New Delhi, India.

Kachinskii, N.A. 1965. Soil physics. Part-1. Publ. Visshayaskhola, Moscow.

Karim, Z., S.M. Saheed, A.B.M. Salauddin, M.K. Alam and A. Huq. 1982. Coastal saline soils and their management in Bangladesh. Soils publication no. 33, BARC.

Kaur, R. 1994. Physics of salt affected soils. In: D.L.N. Rao, N.T. Sing, R.K. Gupta and N.K. Tyagi (eds.) Salinity management for sustainable agriculture. Central Soil Salinity Research Institute, Karnal, India.

Moreno, F., F. Cabreraa, E. Fernndez-Boyb, I. F. Girna, J. E. Fernndeza and B. Bellidoc. 2001. Irrigation with saline water in the reclaimed marsh soils of south-west Spain: impact on soil properties and cotton and sugar beet crops. Agricultural Water Management :48 (2): 133-150. Murphy, J. and J.P. Riley. 1962. A modified single solution method for determination of phosphate in natural waters. Anal. Chem. Acta. 27:31-36. Warrence, N.J., J.W. Bauder and K.E. Pearson. 2002. Basics of salinity and sodicity effects on soil physical properties. Department of Land Resources and Environmental Sciences, Montanta State University-Bozeman. (can be accessed from http:\\ www. waterquality.montana.edu/docs/methane/basics.shtml, visited at 05/03/07) Olsen, S.R., C.V. Cole, F.S. Watanabe and L.A. Dean. 1954. Estimation of available P in soils by extraction with sodium bicarbonate. USDA Cir. 939 Piper, C.S. 1950. Soil and plant analysis. The University of Adelaide Press, Adelaide, Australia.

Reitemeier, R.F. 1943. Semimicroanlysis of saline soil solutions. Indus. and Engin. Chem., Analyt. Ed. 15:393-402, illus.

Rost, C.O. and C.A. Rowles. 1941. A study of factors affecting the stability of soil aggregates. Soil Sci. Soc. Am.J. 421-433. Sparks, D.L. and P.M. Huang. 1985. Physical chemistry of soil potassium. In: Potassium in agriculture soil. ASA-CSSA-SSSA, WI, USA. pp. 201-276.

SRDI, 2003. Soil Salinity in Bangladesh 2000. Soil Resources Development Institute, Dhaka.

Swarup, A. 1994. Chemistry of salt affected soils and fertility management. In: D.L.N. Rao, N.T. Sing, R.K. Gupta and N.K. Tyagi (eds.) Salinity management for sustainable agriculture. Central Soil Salinity Research Institute, Karnal, India.

USDA (United States Department of Agriculture). 2004. Soil Survey Laboratory Manual, Soil survey investigation report no. 42, version 4.0, USDA-NRCS, Nebraska, USA.

Van Bavel, C.M.M. 1949. Mean weight diameter of soil aggregates as a statistical index of aggregation. Soil Sci. Soc. Am. Proc. 14:20-23.

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Signature

(Dr. Mizanur Rahman Bhuiyan) Project Director

Counter Signature

Registrar Khulna University

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Registrar Khulna University

Signature

(Dr. Mizanur Rahman Bhuiyan) Project Director