Investigation of temporal change of soil infiltration rate under saline and sodic water irrigation

Some of agricultural problems in region with warm &dry climate, are saline water &soil resource and their use limitation. On the other hand with population increasing and the growth of water use rate, the optimum use of available water resource(as same as saline and semi saline water) is necessary. an effect of saline water use in irrigation is soil infiltration decreasing. for investigation of temporal change in soil infiltration rate. Several soil layers (clay-loam texture that its initial electrical conductivity was about 1 similar to 2dS(.)m(-1)) were compacted in a big pit(4 meter length, 3m wide and 1.7m depth) and a drain pipe was installed at depth of 1.4m. after it, three wide furrow with 1.2m dung mound, created on the surface of profile. Saline water that applied(EC = 10dS(.)m(-1)), supplied by river salt solving in sweet water. Total volume of weekly irrigation water was 390 liter( 130 liter for each furrow). For soil infiltration investigating, three soil infiltration experiences were implemented in third, sixth and tenth irrigating. In this condition the electrical conductivity at the center of mound increased from 1.5 to 7 dS/m. With regard to conclusion of infiltration test, it is found that climate condition influences significantly on soil physics characteristics, because between third and sixth irrigation the infiltration rate factor decreased 44/09 present, but from sixth to tenth irrigation, this factor decreased 70/32 present. time space between these tests was not very different, therefore we can conclude that the main cause of decreasing in soil infiltration rate, is dispersion of soil ped by saline water( with one capacity ions). On the other hand with encountering warm season of the year(from sixth to tenth irrigation) and also evaporation & temper increasing, damages of saline water use was growing up. We propose that in saline water use the applying of chemical material for soil physics characteristics improvement and so scratching the soil surface for accelerating the rate of infiltration especially in last irrigations.