The Movement of Salts in Saline-Sodic Soils Leached by Enriched Water with Combinations of Phosphogypsum and Humic Acids

Abstract

A laboratory experiment was conducted on saline-sodic soil taken from the 0-30 cm surface layer of clay loam from the farm of a college of agriculture/Anbar university. Sixteen combinations of humic acids (HA1, HA2, HA3, HA4) and phosphogypsum (G1, G2, G3, and G4) at a concentration of 0.5, 1.0, 1.5, and 2.0 gm l−1 for both were used. In addition to two treatments for comparison, commercial clean salt (CS) and Euphrates water. Eighteen polyethylene columns were used, with a length of 60 cm and an inner diameter of 7.1 cm. After the columns were filled with the soil, the columns were washed with enriched water with combinations of humic acids and phosphogypsum. The combinations were mixed with Euphrates water. Washing of column continued until three porous volumes had passed. The results showed that the value of accumulation salts (gm l−1) and the concentrations of sodium, calcium, and magnesium (mmol l−1) increased with the increase in pore volume passing through. The movement of salts and sodium concentrations increased with the increase of phosphogypsum with the increase in the level of humic acid in combination, as the highest value of salts and washed sodium reached 4921.98 gm l−1 and 38794.53 mmol l−1 respectively, in HA4G4 combination, compared to HA1G1, which reached 2436.64 gm l−1 and 20596.27 mmol l−1 respectively. While the calcium and magnesium concentrations increased with the increase of phosphate gypsum and decreased with the increase in the level of humic acid in combination. The combination AH1G4 gave the highest concentrations of 10158.04 and 3577.27 (mmol l−1), compared to HA4G4, which reached 6867.60 gm l−1 and 2473.01 mmol l−1, respectively. The water washing treatments and the salinity treatment (CS) gave the lowest amount of salts and concentrations of sodium, calcium, and magnesium compared to all combinations. The diffusion equation is the best for describing the kinetics of the release of the sodium adsorption rate in the soil over time, as it gave the highest rate of determination coefficient (R2) (which was 0.985 and the lowest standard error) (SEe), which reached 55.439. With an increase in the level of addition of humic acids.