Dynamics of Dissolved Ions in the Rhizosphere Under Flooded Conditions

Abstract

AbstractSoil salinity represents one of the major threats of land degradation and desertification under arid and semi-arid environments. It has an adverse influence on soil-water-plant relationships, posing serious challenges to agricultural productivity. The main objective of this work was to monitor the effect of farmyard manure (FYM) application and irrigation with low-quality water on the dynamics of dissolved salts and yield of rice crop (Oryza sativa L.) under flooded conditions. Accordingly, field and column experiments were carried out with three treatments of irrigation water, namely, tap, saline-sodic, and saline, as well as three rates of FYM application (0, 12, and 24 Mg ha-1). The obtained data indicated that the highest grain yields were found under the treatment with tap water followed by saline water amended with FYM at 24 Mg ha-1. The loss of ions (Na+, HCO3-, Cl-, NO3-, SO42-) from the soil irrigated with saline water was greater than that from irrigated with saline-sodic water. The addition of FYM led to an increase in the leaching of most ions (Na+, HCO3-, and Cl- in particular) and decreased their accumulation in soils irrigated with saline and saline-sodic waters. The regression studies revealed that FYM application may be attributed to the increase in soil resistance against secondary salinization through improving water and salt flux out of the rhizosphere. Under flooded conditions, these findings support the hypothesis that using FYM in conjunction with saline irrigation water has a beneficial effect, while saline-sodic irrigation water should be used with a calcium source.