在干旱半干旱地区,土壤盐渍化是制约农业生产的重要因素。土壤盐分的测定和诊断是土壤盐渍化研究工作中的重要内容,传统上一般通过测定土壤浸提液电导率来测定土壤盐分,过程繁琐,费时费事,不可避免地要破坏原土样。往提倡精准农业的今天,土壤盐分的快速、有效和可靠的原位测定显得非常重要。土壤盐分原位测量方法有多种,在原理上可分为土壤溶液电导率法和土壤表观电导率法两大类。在现有条件下,土壤溶液电导率可通过原位采集土壤溶液后在实验室测定和用上壤盐分传感器直接测定:土壤表观电导率法主要通过四电极、电磁感应仪和时域反射仪测定。本文分析了不同方法和各种仪器的基本原理,探讨了不同方法的优缺点和发展前景,为土壤盐渍化研究中盐分测定方法的选用提供参考。
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.