Diagnosis
of soil salinity and characterizing its spatial variability both vertically and
horizontally are needed to establish control measures in irrigated agriculture.
In this regard, it is essential that salinity development in varying soil
depths be known temporally and spatially. Apparent soil electrical
conductivity, measured by electromagnetic induction instruments, has been
widely used as an auxiliary variable to estimate spatial distribution of field
soil salinity. The main objectives of this paper were adopted a mobile
electromagnetic induction (EMI) system to perform field electromagnetic (EM)
survey in different soil layers, to evaluate the uncertainty through Inverse
Distance Weighted (IDW) and Ordinary Kriging (OK) methods, and to determine
which algorithm is more reliable for the local and spatial uncertainty
assessment. Results showed that EM38 data from apparent soil electrical
conductivity are highly correlated with salinity, more accurate for estimating
salinity from multiple linear regression models, which the correlation
coefficient of 0 - 20, 20 - 40, 40 - 60 and 60 - 80 cm were 0.9090, 0.9228,
0.896 and 0.9085 respectively. The comparison showed that the prediction
accuracy of two methods also displays good performance for soil salinity, the
estimation precision of IDW method (with E = 0.8873, 0.9075, 0.8483 and 0.901,
RPD = 9.64, 8.01, 8.17 and 11.23 in 0 - 20, 20 - 40. 40 - 60 and 60 - 80 cm
soil layers, respectively) was superior to that of OK (with E = 0.8857, 0.872,
0.8744 and 0.8822, RPD = 9.44, 7.83, 8.52 and 10.88, respectively), but
differences of two methods in predictions are not significant. The obtained
salinity map was helpful to display the spatial patterns of soil salinity and
monitor and evaluate the management of salinity.