اثر تيمارهاي مختلف اصلاحي بر آبشويي خاك لكه هاي شور و سديمي جنوب اهواز با استفاده از يك مدل فيزيكي

The influence of different reclamation treatments on leaching of saline- sodic soils using a physical model

Sugarcane is a sensitive crop to soil salinity and therefore, salt-affected soils like southern Khozestan soils must be reclaimed before planting of this crop. Traditional method for reclamation of such salt-affected soils is leaching with local river water (e.g. Karoun) that always give satisfactory results. Sometimes after Ieaching of salts, brown spots (with high salinity and sodicity) appeared on the soil surface which limit crop growth. The aim of this research was to investigate the possibility of different leaching treatment to reclaim such salt-affected soils using a physical model. In this physical model first, hydraulic conductivity of the soil was increased by restructuring the soil and then the soil was leached with water of different salinities to stabilize the soil structure during leaching. The treatments were: leaching with Karoun water (EC=2dSm-1), leaching with saline water (EC-l OdSm-ʹ foe saturating the soil samples and then leaching with Karoun water) and leaching with Karoun water plus 5 Mgha-ʹ gypsum. During leaching, electrical conductivity (EC), sodium absorption ratio (SAR) of percolating water and soil hydraulic conductivity were measured. The experimental design was split plot with three replicates. Results indicated that hydraulic conductivity of the soil of brown spots in comparison with the other area was significantly different (p < 0.01). This might be due to the differences in soil bulk density. However, leaching the soil of brown spots using Karoun river water was successfully completed in the physical model. Therefore, the results indicated that reclamation of such soils is possible by increasing the hydraulic conductivity and leaching with Karoun river water. In the field, however, such process could be limited because of the low hydraulic conductivity and poor drainage conditions of soils. By subsoiling the soil, the hydraulic conductivity could be increased and the brown spots reclaimed if enough drainage conditions are provided.