[Effects of irrigation quota on moisture and salt redistribution in apple orchard soil in arid region].

Taking the salinized apple orchard soil in Qin'an County of Gansu Province, Northwest China as test object, a field experiment was conducted to study the effects of different irrigation quota (0, 900, 1800, 2700, and 3600 m3 x hm(-2)) on the redistribution of moisture and salt in 0-100 cm soil profile on the 10, 20, and 30 d during apple florescence stage. With the increase of irrigation quota, the leached depth of Na+ increased and its hysteretic effect of redistribution was more obvious, "the zero flux plane" of Ca2+ disappeared gradually, the scope of "the zero flux plane" of Mg2+ increased gradually, the leaching-migration mode of Cl- changed from "fluctuation" to "straight-line" and the evaporation-migration changed from "fluctuation" to "ladder", the redistribution pattern of SO4(2-) showed "point", and the position of redistribution and accumulation of HCO3- shifted gradually from the bottom to upper layer in soil profile. In the middle of the soil profile with deeper groundwater table, there existed a "zero flux plane" of salt, which shifted gradually from the upper layer to the bottom during the redistribution of moisture in soil profile, embodying the characteristics of moisture depletion in upland soils.