Management techniques for sustainable farming in a region under desertification based on the control of salt movement in the root zone.

在地处半干旱区的黄河上游流域（中国甘肃）建立了一个试验田，对盐渍土复垦的两种技术进行了试验研究，即本文提出的从灌溉田盐渍土地块中浸出盐分的有效技术——PSW-Well （pumping-up- sal盐水-water-from-well）法；另一种是以种植能从土壤中积极吸收盐分的作物（清洁作物）为基础的生物复垦方法。同一时间，日本也进行了室内实验。结果表明，两种方法分别需要满足以下几个基本条件：①当流域内含水层系统均质，不形成悬空水位时，采用PSW-Well方法效果较好；(2)清洗作物应有利于吸收盐分，对水分的需要量也要低。

An experimental field was established in the upper Yellow River basin (Gansu, China) in a semiarid region and experiments were conducted on the two techniques of reclaiming salt-affected soil, the PSW-Well (pumping-up-saline-water-from-wells) method which was proposed by the present author as an effective technique to leach salts from saline soil plots in irrigated fields, and the biological reclamation method which is based on the cultivation of crops that absorb salts actively from the soil (cleaning crops). Indoor experiments were also done in Japan at the same tome. The results showed that the two techniques need essential conditions to accomplish their purposes, respectively, as follows :(1) The PSW-Well method works well when the aquifer system through the basin is so homogeneous that perched water tables are not developed.(2) Cleaning crops should be good for absorbing salts and low in the demand for water as well.