Recent Concepts in Pedogenesis and Classification of Indian and Tropical Soils

Abstract

Major part of the land area in India lies between Tropic of Cancer and Tropic of Capricorn, and the soils therein are termed "tropical soils". Many however think of tropical soils as the soils of the hot and humid tropics only, exemplified by deep red and highly weathered soils and are often though improperly they are either agriculturally poor or virtually useless. For any nation, soil care through the soil survey needs to be a regular task to gain a detailed knowledge of soils, which is necessary for increasing and maintaining agricultural production to feed the population. In India, soil survey received recognition as an all-India activity following the report of the Stewart Committee in 1947.The National Bureau of Soil Survey and Land Use Planning (NBSS & LUP) under Indian Council of Agricultural Research (ICAR) was established in 1976. The US Soil Taxonomy was adopted in India in 1969 to classify the soils of the country. Since then pedologists identified Vertisols, Mollisols, Alfisols, Ultisols, Aridisols, Inceptisols and Entisols in more than one bio-climatic zones in India, and confirmed the absence of Oxisols, suggesting the soil diversity in India is large. these soils are not confined to a single production system and contribute substantially to India's growing self-sufficiency in food production and food stocks. Although much valuable work has been done throughout the tropics, it has been always difficult to manage these soils to sustain their productivity, and it is more so when comprehensive knowledge on their formation remained incomplete for a long time. Relentless research efforts on basic research during the last few decades by the Indian pedologists and earth scientists, were made to provide insights into several aspects of five pedogenetically important soil orders like Alfisols, Mollisols, Ultisols, Vertisols and Inceptisols with a special attention on their pedology, paleopedology, polygenesis, mineralogy, taxonomy and edaphology. A much better knowledge was made available when the focus of soil research changed qualitatively due to the use of geomorphic history of landscapes alongside the use of high resolution mineralogical, micromorphological and age-control tools. However, the advancement of soil mineralogy knowledge helped to geological periods, and its impact in rationalizing the soil taxonomic database. During the last few decades, many pedologists have pointed out the rationale of framing the concepts of orders, suborders, great groups, and subgroups and suggesting various criteria for grouping soils at the family level of classification with a view to make US Soil Taxonomy more rationale, understandable, and meaningful for Indian tropical soils.