Research and Development Priorities for Soil Restoration

Abstract

Some densely populated regions of the world have severe land shortages. These regions are also characterized by severe problems of soil and environmental degradation. Agriculturally marginal and unsuitable lands, used for food crop production because of land hunger, are being further degraded even to the point of no return from irreversible degradation. For these regions where land resources are insufficient to substantially meet needs, even with the judicious use of off-farm input and ameliorative soil amendments, it is necessary to enhance the soil resource base through res­toration of degraded lands. For restorative considerations, degraded soils can be of three principal categories (Fig. 1). Some soils are unsuitable for agricultural use because of nonavailability of essential inputs, e.g., short­age of irrigation water in dry regions, nonavailability of lime for acidic soils, lack of essential plant nutrients in highly weathered soils. Techni­cally, productivity of such soils can be restored by providing the input required, e.g., use of irrigation, supplemental fertilizer and amendments, choice of suitable crop species and cultivars. However, economic availabil­ity of these input and logistic problems may be major impediments. There are other soils with inherent crop-restrictive properties that limit their use for agricultural production. Some examples of these soils include excessively wet soils, low pH, and high P fixation capacity. Finally, there are soils that are degraded due to land misuse, e.g., eroded and compacted soils, and toxicity due to waste disposal, salt-affected soils, abandoned mines etc. Strategies for land restoration are different for different categories of degraded soils.