Changes in ion(Na)‐holding capacity of amending materials under various salt concentrations

Abstract

Abstract The ion‐holding capacity and strength of ion‐holding function of soil amending materials were determined under various salt (NaCl) concentrations. The phenomena are important for reducing salinity hazard to plant in saline soils. The materials were subjected to salt solutions containing various Na concentrations for 24 h at 25°C. At final stage, the added Na was recovered by 3 subsequent procedures: i) simple filtration, ii) ethanol treatment, and iii) ammonium acetate treatment. Ion‐holding capacity was calculated by subtracting the amount of free ion (Na recovered by simple filtration) from the added ion. The amount of Na remaining in the material after ammonium acetate treatment was used to determine the strength of ion‐holding function. At the lowest NaCl concentration (0.8g Na/100g material), farm manure held 60% of the added Na, which is termed as the ion‐holding capacity. But, at the highest salt concentration (8.0g Na/100g), its ion‐holding capacity was 35%. Ion‐holding capacity of the allophane soil at the lowest salt concentration tretament was 40%, while at the highest salt concentration, its ion‐holding capacity was 24%. Among the materials used in the experiment, Gum tragacanth had the highest ion‐holding capacity It was also found that the ion‐holding capacity of the all the materials tested varied inversely with their ion concentration.