Use of WATSUIT Model for Predicting the Chemical Composition of the Soil Solution Reclaimed with Mined Gypsum

Document Type : Research Paper

Authors

Researchers of Fars Agricultural and Natural Resources Research Center

Abstract

Proper use of saline and sodic soil and water resources is important for increasing crop production in Iran. For this purpose, chemistry models are very helpful in assessing the impact of saline and sodic water and amendment application on soil and plant. In the present study, effect of gypsum on reclamation of sodic soils was investigated at Dorudzan- Marvdasht plain in Fars Province. Moreover, WATSUIT model was used for assessing chemical composition of a soil irrigated with sodic water,(EC=2.17 and SAR=17.1) after application of mined gypsum. The treatments consisted of four gypsum level (0, 3, 6 and 24 meq/l). The experiment was carried out in three replications in 20-m2 plots. Predicted data showed calcium and sulfate concentration increased and soil alkalinity decreased with increasing gypsum rate. Data obtained from the experimental plots indicated that concentration of the ions, salinity(ECe), and sodium adsorption ratio (SAR)  were underestimated by WATSUIT model, mainly due to the low leaching efficiency in the field condition. During reclamation of a sodic soil, salinity threshold for stabilizing soil structure, magnesium to calcium (Mg/Ca) ratio, and the neutralization of alkaline ions to reach a safe value for soil and crop production should be considered. Three mili-equivalents gypsum per liter was sufficient to provide the appropriate values of ECe and SAR to stabilize soil structure, while, based on the model prediction, more gypsum was required for this purpose. The difference is related to the impurity of the applied mined gypsum used in the study. Both the calculated and the measured data show that, even with applying high rates of gypsum, soil alkalinity does not reach a safe range (<1.5 meq/l).  In general, the model predicted that 24meq/l gypsum was the most suitable treatment for reclaiming the soil under the experimental condition.

Keywords


  1. احتشامی، م، ح. اشک تراب، م. ک. سیاهی. 1378. مفاهیم زهکشی و شوری آب و خاک. کمیته ملی آبیاری و زهکشی ایران.
  2. تاجیک، ف.، ح. رحیمی و ا. پذیرا. 1381. اثر ماده آلی خاک، هدایت الکتریکی و نسبت جذب سدیم بر مقاومت کششی خاکدانه‌ها. علوم و فنون کشاورزی و منابع طبیعی، جلد ششم، شماره سوم. 151-160.
  3. مقیمی، ا و پ، مهاجر میلانی.1382 بررسی منحنی شوری و سدیم زدایی میناب. هشتمین کنگره علوم خاک ایران.802-804.
  4. Ayers, R. S. and D. W. Westcot. 1984. Water quality for agriculture. Irrigation and Drainage Pape.FAO. Rome. Italy.
  5. Churchman, G. J. 2002. Sodic soil, reclamation.In: Encyclopedia of Soil Science. Marcel Dekker INC. New York.1224-1228.
  6. Corwin, D. L., J. D. Rhoades, J. Simunek.2006. Leaching requirement for soil salinity control: Steady- state versus transient models. Agric. Water Manag. 90: 165-180.
  7. FAO,UNESCO.1973. Irrigation,Drainage and Salinity. An International Source Book.
  8. Keren, R., and Shainberg. 1981. The efficiency of industrial and mined gypsum in reclamation of a sodic soil-rate of dissolution. Soil Sci. Soc. Am. J.45:103-107.
  9. Mc-Neal, B.L., and N.T. Coleman. 1966.Effect of solution composition on soil hydraulic conductivity. Soil Sci. Soc. Am. Proc. 30:308-312.
  10. Minhas ,P.S,O.P.Sharma and S.G.Patil.(Eds( 25 years of research management of salt- affected soils and use of saline water in agriculture. Centeral Soil Salinity Research Institute, Karnal, India.
  11. B. 2002. sodic soils, formation and global distribution. In: Encyclopedia of Soil Science. Marcel Dekker INC. New York.1213-1217.
  12. Quirk, J.P. and Schofield 1955. The effect of electrolyte concentration on soil permability.  Soil Sci., 6, 163-173.
  13. Rengasamy, P. 2002. Sodic soils. Encyclopedia of soil science: Marcel Dekker. 1210-1212.
  14. Rhoades, J . D. Kandiah, A., Mashali A. M.(1992). The use of saline waters for crop production.Rome: Food Agriculture Organization of the United Nations (FAO).NO.48.
  15. Rhoades, J. D.1977. Potential for using saline agricultural drainage waters for irrigation. P: 85-116. In: proc. Water manage. Irrig. Drain. Vol.177.ASCE,Reno, Nevada, July.17785-116.
  16. L. A. Editor.1954. Diagnosis and improvement of saline and alkali soils USDA Agri Handbook NO.60.
  17. Shainberg, , J.D. Rhoades, R.J. Prather. 1981. Effect of low electrolyte concentration on clay dispersion and hydraulic conductivity of a sodic soil. Soil Sci. Soc. Am. J. 45:273-277.
  18. Stirzaker, R. and Thomson,T. 2004. Fullstop at Ages Bremner: A report on the 2002-3 data to the Angas Bremer water management committee Inc. CSIRO,Land and Water.