ASSESSMENT OF SOLUTE TRANSPORT AND DISTRIBUTION UNDER DRY DRAINAGE CONDITIONS USING A PHYSICAL MODEL

Researchers have recently investigated dry drainage in respect of decreasing environmental effects and investment cost reduction of traditional drainage systems in arid and semi-arid regions. This study investigated the effect of dry drainage on solute transport in a loamy soil using a physical model. The experiment lasted 84 days and results showed that the dry drainage system transferred a significant amount of dissolved salts from the irrigated area into the fallow area. Moreover, sodium, potassium, calcium, nitrate and chloride ions accumulated in the upper layers of soil of the fallow area but magnesium accumulated in the deeper layers. The ratios of sodium, potassium, calcium, magnesium, nitrate and chloride concentrations at the soil surface of the fallow area to the corresponding values in the irrigated area were 1.67, 1.20, 1.81, 0.90, 2.58 and 1.20, respectively. In addition, variation of SAR in the soil profile of the irrigated area was low and its value approached 1.58, but it increased with decreasing soil depths of the fallow area reaching 2.17 at the soil surface of this area. Although the results demonstrated the capability of dry drainage to transfer ions from the irrigated to the fallow area, further investigation regarding different aspects of this method is recommended. (c) 2019 John Wiley & Sons, Ltd.