Studies on saline soils in khon kaen region, northeast thailand I. Physical and chemical properties of saline soils

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1 Soil Science and Plant Nutrition ISSN: (Print) (Online) Journal homepage: Studies on saline soils in khon kaen region, northeast thailand I. Physical and chemical properties of saline soils Pongsiri Patcharapreecha, Bubpha Topark-Ngarm, Itsuo Goto & Makoto Kimura To cite this article: Pongsiri Patcharapreecha, Bubpha Topark-Ngarm, Itsuo Goto & Makoto Kimura (1989) Studies on saline soils in khon kaen region, northeast thailand I. Physical and chemical properties of saline soils, Soil Science and Plant Nutrition, 35:2, , DOI: / To link to this article: Published online: 14 May Submit your article to this journal Article views: 73 View related articles Citing articles: 5 View citing articles Full Terms & Conditions of access and use can be found at Download by: [ ] Date: 30 January 2016, At: 21:00

2 Soil Sci. Plant Nutr. 35 (2), , 1989 STUDIES ON SALINE SOILS IN KHaN KAEN REGION, NORTHEAST THAILAND I. Physical and Chemical Properties of Saline Soils Pongsiri PATCHARAPREECHA, Bubpha TOPARK-NGARM, Itsuo GOTO, and Makoto KIMURA Faculty of Agriculture. Khan Kaen University. Khan Kaen Thailand Faculty of Agriculture. Tokyo University of Agriculture. Setagaya-ku, Tokyo. /56 Japan Faculty of Agriculture. Nagoya University. Chikusa-ku. Nagoya Japan Received April 22, 1988 Saline soils occur extensively in Northeast Thailand. As the climate of this region is clearly differentiated into dry and rainy seasons, salts in the groundwater move up and accumulate on the soil surface during the dry season and are leached down with rainfall during the rainy season. In this paper, the physical and chemical properties concerned with salt movement were investigated for the saline soils in the Khon Kaen Region, Northeast Thailand. Changes in the physical and chemical properties with leaching were also studied in order to determine the effect of rainfall on desaltation. The saline soils in the Khon Kaen Region are generally sandy with low CEC, low content of organic matter and low buffering capacity. The dominant salt is NaCl, which facilitates the dispersion of clay. The main types of clay minerals are I : I type. All the soils contained large amounts of quartz, indicating that they are highly weathered soils. The amount of materials dispersed by water leaching, mainly clay, accounted for the large percentage of clay and silt fractions. Key Words: clay dispersion, EC, ph, desaitation, saline soil. Saline soils which ocur extensively in Northeast Thailand have been cultivated with paddy rice for several decades. It is estimated that saline and salt-affected soils in the Northeast cover an area of 234,600 ha, and account for 5% of the paddy soils (VIJARNSORN and PANICHAPONG 1987). SINANUWONG and TAKAYA (l974a, b) suggested that the sources of soil salinization are "salt-impregnated" claystones, siltstones, and sandstones of upland areas and that the salt is released during weathering. Seasonally high rainfall promotes the transfer of salt by interflow from the weathering zones and salt appears at the surface in the lower parts of the landscape where salt accumulates in the upper horizons due to evapotranspiration (MOORMANN and V AN BREEMEN 1978). The vegetation of this area is of the savannah-type and the climate is 171

3 172 P. PATCHARAPREECHA et al clearly differentiated into dry and rainy seasons. The salts dissolved in the shallow groundwater move up to the soil surface by capillary upward movement and accumulate, resulting in the formation of saline soils. After supply of irrigation water in many locations during the dry season, crop diversification was attempted and yield increases were expected, but problems of salinity, acidity, and water saturation have limited the degree of success achieved (BRINKMAN et al. 1977). Careless irrigation there has, furthermore, brought about additional salinization hazard around the irrigated area. In a series of studies, several experiments were carried out to obtain information about the saline soils in the Khon Kaen Region, from the viewpoint of their amelioration. In this paper, the physical and chemical properties concerned with salt movement were investigated for the saline soils in the Khon Kaen Region. In addition, the changes in the physical and chemical properties with leaching were also studied in order to analyze the effect of rainfall on desaltation. MATERIALS AND METHODS 1) Physical and chemical properties of saline soils. Locations of sampling sites are shown in Fig. 1. All the soils are alluvial soils and they cover upland (KK-3) or paddy (the other 4 sites) fields. A detailed description of their profiles was reported by GOTO et al. (1987). Samples from surface (O-18cm) and subsurface (18-36cm) soils were collected from each site on May 25, 1983 (end of dry season). After the soil Fig. I. Location ofsarnpling sites. a: Bangkok, b: Chiang Mai, c: Khon Kaen, I: site KK-I, Ban Nong Loop, Arnphoe Muang Khon Kaen Province (TropaquaIO; 2: site KK-2, Ban Non Muang Kok Kung, Arnphoe Phon, Khon Kaen Province (Tropaquept); 3: site KK-3, Ban Thurn, Arnphoe Muang, Khon Kaen Province (Paleustult); 4: site KK-4, Ban Kheng, Arnphoe Muang. Khon Kaen Province (Tropaquept); 5: site KK-S, Chonnabot (Halaquept); M: site KK-M, Ban Chiengyun, Arnphoe Chiengyun, Mahasarakarrn Province (Ustifluvent).

4 Physical and Chemical Properties of Saline Soils 173 samples were air-dried and passed through a 2 mm mesh sieve, the soil texture, ph (H 2 0, I : 2.5), EC (l : 5), CEC, content of soluble cations, and soluble anions were determined. Total carbon and nitrogen contents were measured with a 0.5 mm sieved soil sample. 2) Changes of physical and chemical properties by water leaching. Fifty grams of air-dried surface or subsurface soil was mixed with 50 g of quartz sand (6-13 meshes) and packed in a glass column (diameter 3.5 cm). Three hundred milliliters of water was leached through the column and every 2-5 ml ofleachate was collected separately with a fraction collector for the determination of the ph, EC, and turbidity (absorbance at 625 nm wavelength). 3) Clay types and amount of dispersible materials. After the soils were digested with hydrogen peroxide and dispersed with calgon, the clay fraction was collected and the clay types were determined with an X-ray diffraction apparatus. To analyze the dispersibility of the saline soils, 5 g of dry soil was packed in a small glass column (diameter 1.3 cm) and 100 ml of water was percolated. The percolation speed of the water was fixed at ca. 0.5 ml/min. The materials dispersed into the leachate were sedimented with ethanol, centrifuged and weighed after drying. Due to the low organic matter contents in each soil, the materials dispersed into the leachate were expected to be mainly clay and some amount of silt. Therefore the amount of dispersible materials was compared with the amount of total clay or total clay plus silt in each soil. RESULTS AND DISCUSSION J) Physical and chemical properties These saline soils were sandy in texture which ranged from sandy loam to various sand classes (Tables I and 3). Total carbon and total nitrogen contents were very low in all the soils. The ph of these soils which ranged from slightly acidic to slightly alkaline (surface soil: , subsurface soil: ) easily changed by leaching or accumulation of salts. as discussed later. Except for the KK-5 soils. all the soils showed low CEC values (less than 10 meq/ 100 g dry soil) due to the sandy texture and low contents of organic matter. The values of total carbon. total nitrogen and CEe strongly indicated the need for improving the soils by increasing the contents of organic matter and clay, and also by removing salts. The surface soils contained a larger amount of soluble cations and anions than the respective subsurface soils. which indicated the accumulation of salts at the soil surface by an upward movement of groundwater during the dry season. The level of soluble cations and anions was very low in the KK-2 and KK-4 subsurface soils. On the other hand. the KK-3 and KK-5 surface soils showed a very high salt content. The relative intensity of salt accumulation at each site cannot be generalized from these results because it varied with the location and time even within a small area.

5 Table I. General properties of saline soils in Khon Kaen Region. Texture CEC Total Total EC Water soluble cations and anions (meqjloo g soil) ph C (%) N (%) ( Sj ) (meq/ioog m cm soil) Ca2+ Mg2+ Na+ K+ SO/- CI- KK-I U LS O.S tr S L LS S.9 tr 0.4 S.O KK-2 U SL tr tr 3.0 L SL S tr 0.8 tr KK-3 U LS tr tr 11.7 L S O.OOS 7.3 I.S tr 6.1 tr KK-4 U LS S L LS tr 0.9 tr KK-S U LS l.S L SL tr KK-M U LS tr L SL O.OOS tr U, O-IScm; L, 18-36cm; tr, trace. Abbreviations: U, surface soil; L, subsurface soil :J *"" :-0 '"C >...j n ::I: > ;;0 > '"C ;;0 ttl ttl n ::I: > ~ ~...

6 Physical and Chemical Properties of Saline Soils 175 Although sodium ion was the dominant cation in every soil, the KK-5 and KK-M surface soils contained a rather high percentage of calcium ion. Chloride ion was the dominant anion in every soil, especially in the KK-2 and KK-3 soils. From the above results, it is considered that sodium chloride is the main salt dissolved in the soil solution. Table 2. Effect of leaching on soil properties. Onset End Decrease Onset End Leaching EC (ms/cm) EC (ms/cm) of EC ph ph speed (ml/min) KK-I U Gradual L Gradual KK-2" U Gradual <0.1 L II 0.07 Quick <0.1 KK-3 U Quick L Quick KK-4 U Quick L Quick KK-5 U Gradual L Gradual <0.1 KK-M U Gradual L Gradual <0.1 "For the KK-2 soils, only 150 ml of water was leached due to the low permeability. Table 3. Particle size distribution and amount of dispersible materials. Coarse Fine Silt Clay sand (%) sand (%) (%) (%) OM" %Cb %CSC KK-I U L KK-2 U L S KK-3 U S L KK-4 U I I L KK-5 U L KK-M U L U, O-IScm; L, IS-36cm. 80ispersible materials (gjloog soi\). bom % to total clay. COM % to total (clay plus silt).

7 176 P. PATCHARAPREECHA et al SI '" 8 o~o.. o A ph... Surfac. 0 7 TU '" 0 6'" '" LS il/i~o~ooo o C 9 o ~ s "' tqo " ml ph....,..... Subaurfac:. 7' ~ '. o '. LS ' otu EC ~ 0 0 ~ 0 a )DO ml fig. 2. Changes of ph. EC (,us/cm), turbidity (TU), and leaching speed (LS: mljmin) associated with leaching. Therefore, it may be concluded that (I) the saline soils in the Khan Kaen Region are highly weathered sandy textured soils (SL-LS) with low CEC and low organic matter contents, and that (2) NaCI is the dominant soluble salt in the groundwater. 2) Changes of the physical and chemical properties by water leaching The ph of the leachates from every soil increased markedly with the leaching process. The buffering capacity against ph changes (BRINKMAN and DIELMAN 1911) was low because these saline soils are characterized by a sandy texture with a low CEC

8 Physical and Chemical Properties of Saline Soils 177 and low organic matter content. Figure 2 shows the results obtained for the KK-3 soil. It appeared that during the rainy season, the ph value increased with rainfall percolation and was in the alkaline range. At the end of leaching (300 ml), some soils showed a ph higher than 9 (KK-l U, KK-3 U and L, KK-M L) and some others lower than 8 (KK-2 U and L, KK-4 U) (Table 2). In some soils the EC values decreased markedly to less than 0.1 ms/cm with a small amount of water (KK-2 L, KK-3 U and L, KK-4 U and L), whereas in others the EC values decreased slowly (KK-I U and L, KK-2 U, KK-5 U and L, KK-M U and L) (Table 2). In some soils, the soil materials readily dispersed at high EC values (EC values above 10 ms/cm) (KK-3 U and L, KK-4 U, KK-5 L, KK-M L). While no dispersion was observed in the KK-5 and KK-M surface soils. In the KK-l U, KK-2 U, KK-4 U, KK-5 L, and KK-M L soils, the soil materials dispersed gradually. The amount of dispersible materials and the clay type of each soil will be discussed later. In the soils without dispersion the leaching speed was high (> 1 ml/min: KK-5 U, KK-M U), and in some soils with dispersible materials, the leaching speed was rather constant and high (> I ml/min: KK-3 L, KK-4 U and L). On the other hand in the KK-2 U and L, KK-5 L, and KK-M L soils the leaching speed was very low «0.1 ml/ min: Table 2). Fig. 3. X-ray diffractometry of clay fraction (powder sample). Target, Cu; filter. Ni; voltage. 40 kv; current. 30 rna; D. slit: I ; R. slit: 0.3 mm; S. slit: r.

9 178 P. PATCHARAPREECHA et al 3) Clay types and amount of dispersible materials The main types of clay minerals in the saline soils in the Khon Kaen Region were the I : I type (peaks at 4.43 and 7.15 A), and the smectite-type clay mineral (peaks around and 17 A) accounted for a small proportion. These soils contained large amounts of quartz (peak at 4.21 A), suggesting that they were highly weathered (Fig. 3) (BRINKMAN 1977). The amount of dispersible materials from the saline soils is shown in Table 3. Except for the KK-4, KK-5, and KK-M surface soils, the amount of dispersible materials was large in all the soils. In particular, the amount in the subsurface soils reached 1-4% of that of the total soils. The clay dispersion in these soils is generally considered to be high presumably due to the Na-type of clay, though BRINKMAN et al. (1977) reported that clay translocation appeared to be fossil. It is considered that the clay fractions could be leached out completely within a decade, if the clay dispersion and leaching-out were to be as severe as in this soil. The fact that each soil contained not a little amount of clay suggests the possibility of clay retention and/or supply. The mechanisms of clay retention and clay supply with capillary upward water movement will be reported in another paper. Furthermore, from the viewpoint of soil fertility the preservation of clay is very important for these soils due to their low CEC values and low organic matter content. And the amelioration of these soils should be carried out along these lines. Acknowledgments. These studies which were conducted in the framework of the main project entitled "Comparative Ecological Studies on Saline Soils in Coastal and Inland Region of Thailand" were supported by the Grant-in-Aid for Overseas Researches between the Japanese Ministry of Education, Science and Culture, JSPS (Japan Society for the Promotion of Science) and NRCT (National Research Council of Thailand). We thank Professors Jiro Sugi, Toshio Sato, Yasuo Takai, and Sorasith Vacharotayan, Dr. Chaitat Pairintra, Dr. Sujin Jinahyon, and Dr. Samarn Panichapong, the coordinators of this project, for their encouragement. We also wish to express our sincere thanks to Dr. Santibhab Panchaban, Dr. Pompimorn Suriyajantratong, Dr. Pimpan Jermsawatdipong, Mr. Roengsak Katawetin, Dr. Michihiro Hara, and Dr. Masayuki Nemoto for their valuable suggestions and cooperation. We would like to express our special thanks to Dr. Yukio Sato of Chiba University, Japan, for his assistance in the X-ray diffraction analyses. REFERENCES BRINKMAN, R. 1977: Problem hydromorphic soils in north-east Thailand. 2. Physical and chemical aspects, mineralogy and genesis. Neth. J. Agric. Sci, 25, BRINKMAN, R. and DIELMAN, PJ. 1977: Problem hydromorphic soils in north-east Thailand. 3. Saline-acid conditions, reclamation, improvement and management. Neth. J. Agric. Sci., 25, BRINKMAN, R., JONGMANS, A.G., and MIEDEMA, R. 1977: Problem hydromorphic soils in north-east Thailand. I. Environment and soil morphology. Neth. J. Agric. Sci, 15, \ GOTO, I., NINAKI, M., PATCHARAPREECHA, P., and TOPARK-NGARM, B. 1987: Limiting factors for crop growth in saline soils. In Coastal and Inland Salt-Affected Soils in Thailand, Ed. Y. Takai, T.

10 Physical and Chemical Properties of Saline Soils 179 Nagano, M. Kimura, J. Sugi, and S. Vacharotayan, p , Nodai Research Institute, Tokyo University of Agriculture, Tokyo, Japan MOORMANN, F.R. and V AN BREEMEN, N. 1978: Rice Soil, Water, Land, p , International Rice Research Institute, Laguna, Philippines SINANUWONG, S. and TAKAYA, Y. 1974a: Saline soils in North East Thailand. South East Asian Stud., 12, SINANUWONG, S. and TAKAYA. Y. 1974b: Distribution of saline soils in the Khorat Basin of Thailand. South East Asian Stud., 12, VIJARNSORN, P. and PANICHAPONG, S. 1987: General description of saline and peat/acid sulfate soils in Thailand from the meteorological, topographical and pedological viewpoints. In Coastal and Inland Salt-Affected Soils in Thailand, Ed. Y. Takai. T. Nagano, M. Kimura, J. Sugi. and S. Vacharotayan. p Nodai Research Institute. Tokyo University of Agriculture. Tokyo. Japan