Determining soil salt distribution by electromagnetic induction of cotton field under different film-mulched irrigation techniques

Specific field sites in cotton field were selected for different film-mulched irrigation techniques, including one-mulch/one-pipe/four-row irrigation mode (114 mode), one-mulch/two-pipe/four-row irrigation mode (124 mode) and flooding irrigation mode (FIM). Then apparent electrical conductivities (EC_a) were measured at different heights and locations of the sites, including wide-row with mulch, narrow-row with mulch and inter mulch. Soil profile salinity interpretation models were established to evaluate the horizontal and vertical distribution characteristics of soil salt. The study showed that, in horizontal direction, soil salt content in narrow-row with mulch was more than that in wide-row with mulch in 114 mode in the 0~10 cm soil layer. Under 124 mode, soil salt content in narrow-row with mulch was less than that in wide-row with mulch. There was no obvious difference at different locations under FIM. In vertical direction, surface accumulation occurred in all three modes (114 mode, 124 mode and FIM). The maximum accumulation occurred in the 10~20 cm soil layer, and soil salt content tended to be stable in layers below 80 cm. Soil profile salinity interpretation models were not only precise in results, but also convenient in use. The models could therefore be used to accurately predict soil salt distribution of cotton field under different film-mulched irrigation techniques. This was significant for improving agricultural production.