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AND SODIUM ADSORPTION RATIO (SAR) IN SOME SOILS OF THE AMİK PLAIN Necat Ağca, Kemal Doğan Mustafa Kemal University, Faculty of Agriculture, Department of Soil Science TR 31040 Antakya-Turkey ABSTRACT The aim of this research has been to determine the relationships between ESR and SAR in some soils of the Amik Plain as affected by some chemical properties of these soils. pH, EC, soluble sodium, calcium, magnesium, bicarbonate and chloride contents of the soils ranged between 7.37-8.19, 0.506-6.819 mS/cm, 0.33-21.28 me/l, 2.07-25.04 me/l, 0.53-61.88 me/l, 0.34-4.12 me/l and 0.37-34.72 me/l, respectively. The ESR and SAR values of the soils were in range of 0.0049-0.0611 and 0.22-6.09, respectively. The Gapon coefficients (Kg) of ESR-SAR relationships changed between 0.0056-0.0120. The coefficient of single regression equation which was determined for all data is 0.0090. Coefficients of all regression equations were found to be statistically significant. The order of alkalinization tendency of the layers in the profile of the soils is 50-90 cm> 0-20 cm> 20-50 cm. INTRODUCTION Exchangeable Sodium Ratio (ESR) is determined from exchangeable Sodium (Nax) and cation exchange capacity (CEC) (me/100g) by the following relationship: ESR = Nax/(CEC-Nax) Sodium Adsorption Ratio (SAR) is, on the other hand, calculated from concentration of cations (me/l) in the saturation extract by the equation: Na/[(Ca+Mg)/2]1/2 (Harron et al., 1983). The ESR is significantly correlated to the SAR for many soils (Bower, 1959; Paliwal and Gandhi, 1976; Poonia and Talibudeen, 1977). Thus, once the relationships between ESR and SAR has been determined, ESR can be estimated from this relationship (Bower, 1959). But, ESR-SAR relationship is affected by some soil properties (Poonia and Talibudeen, 1977). Therefore, it is necessary to determine this relationship individualy for soils of different regions. ESR-SAR equation which was derived to investigate relation between composition of exchange and solution phases by Gapon in 1933, assume that there is a linear correlation between similar cations in solution and exchange phases. Afterwards, this equation is reorganized by Richards (1954) as follows. ESR = Kg x SAR Where, Kg is Gapon coefficient. There are many researches on the ESR-SAR relationship. It was evident form the findings of Yeşilsoy (1969), Al Chalabi and Pasricha (1981), Hall and Berg (1983), Guth and Brown (1985), Ağca and Derici (1991), Saltalı (1996) and Walter (1997), that the Gapon selectivity coefficient (Kg) is not constant but can change in a rather wide range, from 0.0041 to 0.0875. The aim of this research has been to determine the relationships between ESR and SAR in some soils of the Amik Plain as affected by some chemical properties of these soils. Specifically, a reliable estimate of the ESR form the SAR would be useful for characterization of alkali soils and provide information regarding their reclamation and alkalization tendency. MATERIALS and METHODS The research area is located in Amik plain. The Amik plain, which is one of the most important agricultural areas in Turkey, is situated in Southern Part of the country. The area, in general, has Mediteranean climate, but receives more than the usual precipitation. In this research, first, two different test areas which can represent plain were selected in the Amik Plain. Each area contained two intersecting lines: A and B lines on the first area and C and D lines on the second area. Then, a total of 63 disturbed soil samples were taken from 23 spots on these four lines at 0-20, 20-50 and 50-90 cm depths in June 1998. The spots were selected at one kilometer intervals. Soil samples were analysed for pH and electrical conductivity (EC) (in the saturation extract), exchangeable sodium, cation exchange capacity (CEC), organic matter, soluble cations and anions by common methods (Richards, 1954; Rhoades, 1982; Sparks, 1996). The ESR values were calculated by using exchangeable sodium and CEC values, whereas, calculation of SAR was based on soluble sodium, calcium and magnesium concentrations (Richards, 1954). Then, relationships between ESR and SAR values were examined by linear regression analyses (Jurinak et al., 1984), and reported for individual lines, averages for test areas and as overall average for the region at each soil depth. Furthermore, the ESR equations were calculated on the basis of EC ranges of the soils. RESULTS and DISCUSSION Some Chemical Properties and ESR and SAR values of the Soils were given in Table 1. The pH varied between 7.37-8.19 and EC was in range of 0.506-6.819 mS/cm. Contents of soluble sodium, potassium, calcium and magnesium in the soils were found between 0.33 and 21.28, 0.08 and 0.66, 2.07 and 25.04, and 0.53 and 61.88 me/l, respectievly. The range of carbonate, bicarbonate and chloride concentration of the soils were between 0.20-1.40, 0.34-4.12 and 0.37-34.72 me/l, respectively. The soluble sodium, EC, ESR and SAR values, in general, increased and soluble potassium decreased with increasing depth. But, there was not a definite variation in other soil properties with increasing depth. In addition, there was a wide variation of soil properties among spots at each depth. The ESR values were between 0.0049 and 0.0611 while the SAR values were in range of 0.22-6.09. The lowest ESR and SAR values were found for spot B6 (0-20 cm) and the highest for spot D5 (50-90 cm). The ESR increased in accord with SAR values (Table 1).  The regression equations for ESR-SAR relationships, determined for individual lines, averages for test areas and as overall average for the region at each soil depth and on the basis of EC values of the soils were shown in Table 2. The Gapon coefficients (Kg) of ESR-SAR relationships changed from 0.0056 to 0.0120. The lowest Kg value was found for line B (0-20cm) and the highest for line D (0-20 cm). The coefficient of single regression equation which was determined for all data is 0.0090. The Kg values obtained from ESR and SAR data in this study are in agreement with those of previous studies. As shown in Table 2, Kg values of the soils were different for each line and each depth. This variability may be stemming from differences in soil properties. in fact, ESR-SAR relationship is affected by soil properties such as CEC, organic matter, surface charge density, salt content (Bower, 1959; Paliwal and Gandhi, 1976; Jurinak et al., 1984). In this research, Kg values, in general, decreased with increasing organic matter content and was higher in surface layers having high organic matter than in sublayer with low organic matter. For example, in the Line B, 0-20 cm depth having the highest organic matter content has the lowest Kg value. Similar results were reported by other researchers (Poonia and Talibudeen,1977; Harron et al., 1983; Ağca and Derici, 1991; Saltalı 1996). The Kg values which were obtained for four different salinity classes of the soils varied between 0.0080 and 0.0144 (Table 2). According to data in Table 2, it is obvious that Kg is affected by salinity (EC) and Kg decreases up to 4.5 mS/cm of EC then incerases as the salinity increases. This results are in agreement with the results shown by Harron at al. (1983) and Levy and More (1965) but in dissagreement with those of Frenkel and Alperovitch (1984) and Poonia et al. (1984). The inconsistent reaction of Kg to salinity may be result from mineralogical properties of the soils. Because, Jurinak at al. (1984) indicated that there may be an interaction between clay minerals and salts, and clay mineral-salinity interaction may influence both CEC and cation preference of exchange phases. Although the relationship between ESR and SAR of soils used in this research are affected by soil properties, it is difficult to isolate the individual effects of these properties on Kg since there were no significant correlations between Kg and individual soil parameters. As indicated also by Ağca and Derici (1991), the differences among Kg values may be result from combined effect of these characteristics. Most of the regression equations were found to be statistically significant at 0.001 level. This outcome means that regression equations obtained may be used for calculating ESR values from SAR data. But, the use of equations determined at each depth on each line is more useful for sensitive investigations.  Gapon coefficients may be used as indicators of alkalinization tendency in soils. Because, at equilibrium between solid and liquid phase of the soils, the ESR values which are dependable criteria for alkalinization, depend on firstly Kg values of the equations and to some extent intercept values of equations at any given SAR value. In other words, the higher Kg value shows the higher ESR value in the same soils at any given SAR value (Ağca et al., 1998). Therefore, considering the overall average, the order of alkalinization tendency of the soil layers in the profile of the soils is 50-90 cm> 0-20 cm> 20-50 cm. This means that the alkalinization will firstly begin at 50-90 cm layer then follow at 0-20 and 20-50 cm layers of the soils, if conditions for alkalinization are imposed, although there are no alkalinity problems in these soils yet. REFERENCES Ağca N., Derici R. (1991). The Relationships Between the Exchangeable Sodium Ratio (ESR) and the Sodium Adsorption Ratio (SAR) on Widespread Soil Series in the Harran Plain. Turkish J. of Agriculture and Forestry. 15 (2): 239-247 (in Turkish). Ağca N., Aydın M., Derici M.R., Yeşilsoy M.Ş., Erşahin S. (1998). Alkalization Tendency and Infiltration Rate Relationships of Widely Soil Series in Harran Plain, Turkey. Proceedings of M. Şefik Yeşilsoy International Symposium on Arid Region Soils (21-25 September 1998, Menemen- İzmir-Turkey). pp. 114-119. Al Chalabi A.S. Pasricha N.S. (1981). Sodium-Calcium Exchange in Some Salt-Affected Soils. J. Indian Society Soil Science. 29 (1): 46-49. Bower C.A. (1959). Cation Exchange Equilibrium in Soils Affected by Sodium Salts. Soil Science. 88: 32- 35. Frenkel H., Alperovitch N. (1984). The Effect of Mineral Weathering and Soil Solution Concentration on ESR-SAR Relationships of Arid and Semi-arid Zone Soils from Israel. Journal of Soil Science. 35: 367-372. Guth D.L, Brown K.W. (1985). A Comparsion of the SAR and Vaneslow Equations in Three Soils. Soil Science. 140 (5): 356-361. Hall A., Berg W.A. (1983). Prediction of the Sodium Hazard in Coal Mine Overburden. Reclamation and Revegetation Research. 2: 191-204. Harron W.R.A., Webster G. R., Cairns R.,R. (1983). Relationships Between Exchangeable Sodium and Sodium Adsorption Ratio in a Solonetzic Soil Association. Can. J. Soil Sci. 63: 461-467. Jurinak J.J., Amrhein C., Wagenet R.J. (1984). Sodic Hazard: The Effect of SAR and Salinity in Soils and Overburden Materials. Soil Science. 137(3): 152-159. Levy R., Mor E. (1965). Soluble and Exchangeable Cation Ratios in Some Soils of Israel. Journal of Soil Science. 16(2): 290-295. P aliwal K.V., Gandhi A.D. (1976). Effect of Salinity, SAR, Ca:Mg Ratio in Irrigation Water and Soil Texture on the Predictability of Exchangeable Sodium Percentage. Soil Science. 122: 85-90. Poonia S.R., Mehta S.C., Pal R. (1984). The Effects of Electrolyte Concentrations on Calcium-Sodium Exchange Equilibria in Two Soil Samples of India. Geoderma. 32:63-70. Poonia S.R., Talibudeen O. (1977). Sodium-Calcium Exchange Equilibria in Salt-Affected and Normal Soils. Journal of Soil Science. 28: 276-288. Rhoades J.D. (1982). Soluble Salts. Methods of Soil Analysis. No.9. Part.2 (ed. A.L. Page). American Soc. of Agronomy, Inc. Soil Sci. Society of America, Inc. Madison, Wisconsin USA. P.167-179. Richards L.,A. (1954). Diagnosis and Improvement of Saline and Alkali Soils. SDA, Handbook 60. 160 p. Saltalı K. (1996). A Study on Salt Dynamics and Determination of Tendency for Alkalinization of Tokat- Kazova Soils. Gaziosmanpaşa University, Graduate School of Natural and Applied Science, Department of Soil Science (Ph D. Thesis). 95 p. (in Turkish). Sparks D.,L. (1996). Methods of Soil Analysis. Part 3. Chemical Methods. SSSA. Madison, Wisconsin, USA. Walter F. (1997). Extraction of Forest Tree Volume from Carabas SAR data. Scandinavian Journal of Forest Recearch. 12: 4, 370-374. Yeşilsoy, M.Ş. (1969). The Cation Exchange Characteristics of the Soils in the Trakya Region. Proceedings of 1.,2. and 3. Congres of Soil Science Society of Turkey. pp. 47-59. (in Turkish). |