Abstract:Soil salinization is one of the limiting factors of agricultural productivity in arid and semi-arid regions. It is essential to determine soil salinity in a reliable but easy method. Soil salinity has been customarily defined and assessed in terms of laboratory measurements of the electrical conductivity of the extracts under different soil to water ratios, which has to destory the soil samples and is labour and time consuming. Precision agriculture requires low-cost, rapid, and reliable methods for determining soil salinity in the field. There are several approaches to determine soil salinity in situ which can be roughly classified into soil solution electrical conductivity measurement and soil apparent electrical conductivity measurement. In nowadays, soil solution electrical conductivity could be determined by measuring electrical conductivity of soil solution sampled in situ with soil solution sampler or by soil salinity sensors; soil apparent electrical conductivity could be determined by four-electrode method, electromagnetic induction and time domain refletrometry. In this paper, the basic principle, the advantages and disadvantages of different approaches or instruments and the development prospects of in situ determination of soil salinity were discussed for a reference in selection of soil salt determination method in soil salinization study.