Concepts Concerned with Salt-Affected Soils

Abstract

With world population growth, the demand for food is increasing, but the area of arable land is reaching its limit. Moreover, these lands may even decrease owing to land-use changes associated with socioeconomic development. In China especially, which is one of the most populated countries in the world, its cultivated land area cannot keep pace with the population, and farmland is gradually declining as urbanization continues to progress. In order to meet the demand for grain production and alleviate the pressure on current arable land, saline land must be reclaimed. There are different opinions on how to define salt-affected soil in the field. Generally speaking, salt-affected soil can be defined as soil containing enough soluble salts to interfere with the growth of most crop plants. Also, the conductivity of the saturation extract tends to be greater than 4 mmhos/cm, the exchangeable-sodium percentage is less than 15 %, and the pH is usually less than 8.5. In order to describe specific cases, there are other terms concerned with salt-affected soils, and these are also discussed.