عنوان مقاله [English]
Background and Objective: Amelioration of saline-sodic soils by organic matter has been widely reported as a cheap and suitable alternative to minerals. Investigations shows that application of organic modifiers in saline-sodic soils can directly or indirectly increase the growth of salt tolerant plants by increasing soil nutrient content and the abundance of soil organisms. However, no study has been done on the effect of dissolve organic carbon (DOC) on reclamation of saline-sodic soil. Therefore, the purpose of this study was to investigate the role of DOC on amelioration of saline-sodic soil with clay tissue.
Materials and Methods: In this research, the ameliorative potential of DOC on some chemical properties, including the concentration of soluble cations and anions of saline- sodic soil with clay texture was studied in the Karfoon area in Mazandaran province. Treatments included sugar cane extract, poultry manure and cow manure, added to saline-sodic soil at three levels (0, 100 and 200 mg per liter of DOC). The experiments were carried out in two stages of incubation and leaching, the soils were analyzed after each stage and the concentration of the elements and the electrical conductivity and their sodium adsorption ratio were calculated.
Results: The results indicate that in the incubation stage, application of DOC increased the amount of soluble elements and electrical conductivity compared to the control soil. In the leaching experiments, the highest amount of elements in the leachate was related to the soils treated with higher concentrations of DOC (200 mg / L). Results from analysis of soil in columns after leaching stage showed that in all soils treated with DOC, electrical conductivity and sodium adsorption ratio decreased compared to control soil, the highest reduction was observed in soils treated with 200 mg/L Bagasse extract.
Conclusion: Results showed that application of DOC in the incubation stage increased concentration of elements and electrical conductivity of the soil compared to the control soil, but decreased the pH level compared to the control soil. Therefore, application of DOC alone will not have a significant effect on the amelioration of saline-sodic soils. Results of the leaching stage show that leaching was effective in reducing the salinity and the sodium content of the soil, regardless of the modifier application, although the addition of DOC has increased this effect . In general, it can be concluded that application of DOC can increase the displacement of sodium on exchange sites and and accelerate its leaching by increasing the concentration of soluble bivalent cations.