| Abstract:
Soil infiltration problems occur as a result of irrigation with saline-sodic waters. Knowledge of the soil infiltration parameters is necessary for efficient furrow irrigation. This experiment was carried out in the experimental farm of Tehran University at Karaj, in 2002. The method used for determination of the basic infiltration rate was inflow-outflow. The basic infiltrations were measured on twelve irrigation events using different water qualities (salinity-sodicity). Three water qualities as control (EC=0.6 dS/m, SAR=0.9), low salinity and high SAR (EC=2 dS/m, SAR=10) and high salinity and very high sodicity (EC=6 dS/m, SAR=30) were tested in furrows which were planted with maize. Irrigation water treatments were created by adding NaCl to irrigation water. Results showed that with increasing sodium adsorption ratio in waters, the basic infiltration rate at the end of period reduced markedly than control. Basic infiltration rate decreased about 41% in very high SAR compared with low SAR treatment (control). High SAR value adversely affected the basic infiltration rate. The observed results for these saline-sodic treatments were attributed to formation of a depositional seal layer, soil consolidation and different levels of irrigation water salinity and sodicity.
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