Crop production under salt affected black soils

Abstract

In the course of the present century, the world population has increased from less than two thousand million to over five and a half thousand million. Until one hundred years ago, the expanding population’s increasing needs for food, fuel, fibre and construction materials were met from the land by cultivating progressively larger areas. The much greater increase in population during this century has been supported mainly by intensifying the use of much of the land that is already cultivated. In the next 25 years a further 2000 million people will be added to the global population. Most of these people will live in the tropics. As a result , the demands which will be placed on the soil and water resources of the tropics will far exceed those of the past. According to the FAO Land and Plant Nutrition Management Service, over 6% of the world's land is affected by either salinity or sodicity (Table 1). The term salt-affected refers to soils that are saline or sodic, and these cover over 400 million hectares, which is over 6% of the world land area (Table 1) . Much of the world’s land is not cultivated, but a significant proportion of cultivated land is salt-affected. Of the current 230 million ha of irrigated land, 45 million ha are salt-affected (19.5 percent) and of the 1,500 million ha under dryland agriculture, 32 million are salt-affected to varying degrees (2.1 percent).