EFFECTS OF LEACHING ON THE RECLAMATION OF SALINE SOILS AS AFFECTED BY DIFFERENT ORGANIC AND INORGANIC AMENDMENTS

Abstract

Soil salinity, which poses one of the greatest threats to sustainable crop production worldwide, can be ameliorated through various approaches, such as leaching, mulching, and amendment application. The effects of leaching and amendments on saline soil reclamation have been studied separately, but their interaction is poorly elucidated. Therefore, a column experiment was designed with soils that were subjected to leaching with 2 and 4 pore volume (PV) of water and compared with non-leached soils (NLS) to observe the effects of leaching on saline soil and leachate characteristics under different organic (vermicompost [VC] and wood ash [WA]) and inorganic (zeolite) amendments at two different rates (1 and 2 g 100 g−1) and their combinations. Results revealed that the electrical conductivity (EC) of the soil decreased, whereas the EC of the leachate increased as the PV of water increased. Regardless of the treatments, the concentrations of sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) in the leachate increased. By contrast, their concentrations in the leached soils decreased as the PV of water increased. WA contributed to a significant increase (p < 0.01) in the EC and the concentrations of cations, especially K+ and Ca2+, in the soils and leachates. The higher the rates of the amendment, the greater the increment in the EC and cation concentrations. Incorporating amendments could be important sources of cations, thereby limiting the entry of Na+ into the exchange complex and facilitating leaching with percolating water. The response of spinach (Spinacia oleracea) in terms of yield parameters to 2 PV of leached soils was significantly better than that of NLS, suggesting that soil leaching could significantly influence plant functioning in highly saline soils. This study suggested that the irrigation of saline soils under different organic and inorganic amendments before cultivation might affect salt leaching and soil nutrient dynamics, thereby influencing plant growth and yield.