STABILITY OF A CALCAREOUS SALINE-SODIC SOIL DURING RECLAMATION

General guidelines to reclaim saline or sodic soils do not adequately consider variables such as pH and the presence of organic matter that are known to affect soil stability. Poor structural stability of sodic , saline-sodic, and high-pa soils adversely influences crop yields; pr omotes piping, tunneling, and slope erosion; and can accelerate the fa ilure of water conveyance systems. We evaluated six soil tests, used t o measure physico-chemical properties, for their suitability to evalua te the structural stability of a calcareous, saline-sodic soil under r eclamation. The stability tests were wilting point, plastic limit, coe fficient of linear extensibility (COLE(rod)), water content at 0.03 MP a, liquid limit, and dispersion index. The range of electrical conduct ivity (EC) studied was 0.5 to 20 dS m(-1), sodium adsorption ratio (SA R) 0 to 400 (mmol L(-1))(0.5), and pH 8.4 to 10.5. The results obtaine d indicate that the amount of water necessary for a soil to how under standard conditions for the liquid limit test decreased an average of 25% when the EC decreased from 40 to 2 dS m(-1). The liquid limit and EC showed a linear correlation (R(2) = 0.785); therefore, the liquid l imit was considered to be an appropriate index to evaluate the physica l properties of a soil under a leaching process. Plasticity index and available cater were more useful in the evaluation of the mechanical p roperties of the soil when we used amendments. Liquid limit combined w ith the water content of the soil at 0.03 MPa was the most useful tool for evaluating soil structural stability during reclamation.