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Abstract This study aims to investigate the effect of using saline irrigation water of different qualities on the main physical and chemical properties of soils. The area of study was located at the north of Edko lake, EI-Behera governorate. This area included three types of irrigation water namely, EIMahodeia canal fresh water, uEC ~ 0.59 dSm-1(G1)” drainage water of EC 3.03 dSm-1 (G4) and two mixtures of both water types, having mixing ratios of 2:1 and 1:2 fresh to drainage water, EC values of these mixtures were 1.63 dSm-1(G2) and 1.99 dSm-1 (G3). This study was represented by 13 soil profiles. ”Disturbed and undisturbed samples were taken from each layer (0- 30, 30-60, 60-90 cm) of each soil profile to determine the chemical and physical properties Le. electrical conductivity soil reaction, organic matter, soluble cations and anions, exchangeable cations, total carbonate, particle size distribution, water stable aggregate, pore size distribution total porosity, saturated hydraulic conductiVity and bulk density. The obtained results revealed the following: The canal fresh water (G1) was free of residual sodium carbonate, having EC of 0.59 dSm-1 and SAR of 1.21 and so was classified according to USS Salinity Laboratory Staff (1954) as C2S1. The other three grades of irrigation water also free of residual sodium carbonate and classified as C3S1 • C352 and C.•52 or C.•S3, respectively. The decreasing order of soluble cations of the fresh water was Mg++ > Na+> Ca++ while in the drainage water the order was Na+> Mg++> Ca++. The distribution of soluble anions in the fresh water was in the order of HC03-> S04= > cr, whereas Clwas the dominant all the other types of irrigation water; followed by HC03- and then S04= soluble anion. The pH values of the soil under consideration were not markedly affected by water irrigation of different qualities. Increasing of irrigation water salinity (ECwI) from 0.59 dSm-1 (G1) to 3.05 dsm” (G4) increased the soil salinity from 2.22 dSm-1 as high as 12.70 dSm-1 for G1 and G4 respectively. Results showed that the soluble sodium of the studied soil profile was the dominant soluble cations followed by Mg++, Ca++ and t< and tended to increase with increasing of drainage water ratio, while the distribution of soluble anions showed that the soluble chloride was the dominant soluble anion followed by sulphate, while the soluble bicarbonate was approximately constant. Exchangeable calcium tended to be gradually decreased with increasing of drainage water ratio. Since the exchangeable calcium values amounted to a range of 16.03-23.35 me/100 g soil in the soil irrigated with fresh water, this level was dropped to a range of 4.24-13.51 me/100 g soil with drainage water irrigation. The irrigation water mixture yielded values in between these two extremes. Such results may attract attention to the probable hazard due to long period irrigation with low water quality where Na+ replace Ca” gradUally on the exchangeable sites of the clay complex. The texture class of soils profile under study is clay with clay percent of about 55-74 as a mean values. The organic matter content was generally low and ranged between 0.68% and 2.13%, and decreased with depth. Also, carbonate content was generally low (*1.09 % and 2.98%) as a mean values. With increasing of total soluble salts (EC values) from 2.22 dsm’ (G1) to 4.54 dSm-1 (G2), the aggregate state was decreased to the lowest mean values of 46.08. However with increasing of EC values from 4.5 dSm-1 (G2) to 12.7 dSm-1 (G4) the aggregate state is again improved and reached to its maximum value 52.91 in the highest saline soil (G4). The quickly drainable pores, slowly drainable pores and water holding pores were proportionally related to exchangeable calcium inversely to EC, ESP and exchangeable magnesium, while an opposite trend was exhibited with fine capillary pores. On the other hand the increasing of EC, ESP and also exchangeable magnesium level act as dispersing agent lead to encourage the abundance of micro on the expense of macro pores. As the soil total soluble salts, exchangeable sodium and exchangeable magnesium increased the upper limits of both filed capacity and wilting point were also increased. However, effect of the Ee, ESP as well as exchangeable magnesium were more effective in raising the upper limit of the wilting point level rather than that of the field capacity, as a consequence the available water content was reversely related to these parameters. The exchangeable calcium lowers the upper limits of both filed capacity and wilting point but its effected on lowering the upper limit of wilting point is more- pronounced, hence an increase of available water is achieved with increasing of exchangeable calcium. The saturated hydraulic conductivity (K) values were generally very low, that may be due to the dominancy of the clay fraction in the tested soils. The general mean values of hydraulic conductivity were parallel with general mean values of aggregate state and mean weight diameter. from the previous results and with respect to EC and ESP it is evident that the soil were deteriorated by usinq the bad quality of irrigation, since the soil were changed from normal to saline and then to saline sodic soil. A successful irrigated agriculture requires permanent control of salinity and irrigation water. Reclamation of affected soil by means of improved drainage, chemical treatments and leaching of salts can reduce natural hazard. Gypsum is the most commonly used amendments for reclaiming sodium-affected soil and reducing the harmful effects of high sodium irrigation water. Gypsum added to sodic soil increases permeability by increasing electrolyte concentration and by reducing exchangeable sodium. Finally the obtained results may attract the attention to the hazard predicted upon irrigating the soils with low quality waters particularly for long periods and in absence of effective drainage systems. |