Management strategies for sustainable crop production in saline Vertsisols

Abstract

In the course of the present century, the world population has increased from less than two thousand million to over Six 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 200 million people will be added to global population and most of this growth will take place 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. In the arid and semi arid regions where low rainfall coupled with uncertainty of its occurrence has been the limiting factor in the crop production. The salt affected soils are an important ecological entity in India and it is estimated that nearly 6.73 m ha is affected with this menace. The problem being dynamic in nature, the extent keeps on changing. The extent of Vertisols covers a total of about 340 million hectares. Most Vertisols occur in the semi-arid tropics, mainly in Gezira and other parts of central Sudan, South Africa, Ethiopia, and Tanzania in Africa, the Deccan plateau of India in Asia and Australia. The Extent of Vertisols and associated soils in India is approximately 72.9 million hectares, comprising 22.2 % of total geographical area of the country. Vertisols and associated soils are mainly confined between 8045’ to 260 N latitude and 60 to 83 0 E longitude in India, extensively occurring in Madhya Pradesh, Maharashtra, Gujarat, Andhra Pradesh, Tamil Nadu and Rajasthan. Vertisols are imperfectly to poorly drained, leaching of soluble weathering products is limited, the contents of available calcium and magnesium are high and pH is above 7. This is due to the very low hydraulic conductivity. As a result of soil degradation, there have been negative effects such as decrease in farm production due to abandoned farm lands, decline in resource productivity, and cut back in resources use. Similarly at the regional level there have been displacement of labour from agriculture, widening of income disparities and adverse effect on the sustainability of agriculture based sectors. For better management of land and water resources would not only tackle dynamic nature of soil salinity but also increase the productivity of the soils.