Saturday, July 20, 2019
Lateritic Soils in the Tropics: The Problems and Management Possibiliti
Lateritic Soils in the Tropics: The Problems and Management Possibilities The soil name "laterite" comes from a Latin word "later" meaning brick. It is an appropriate name, as soils under this classification are characterized by forming hard, impenetrable and often irreversible pans when dried (Soils and Soil Fertility 1993). Lateritic soils are also characterized by their low soil fertility. Due to the high rate of weathering, and resulting low charge minerals, the soil is unable to retain the nutrients needed for plant growth (Ibid., Coleman 1989). Laterite soils have many names. In the United Nations Food and Agriculture Organization they have been named Ferralsols and Acrisols, and in the United States Department of Agriculture Soil Taxonomy, Oxisols and Ultisols. Ferralsols, like Oxisols have high iron and aluminum oxide contents, whereas Acrisols and Ultisols are characterized by extreme stages of weathering (Oades 1989). Below, we take a look at the formation of lateritic soils, the importance of biota for soil fertility and some suggestions for laterite management. Soil Formation Both climate and parent material are important in the pedogenic processes which go into the formation of lateritic soils. Laterite soils are formed in moist, well-drained, tropical conditions (usually in areas with a significant dry season) on a variety of different types of rocks with high iron content. (See Appendix 1.) Initial stages of weathering lead to the formation of kaolinite and iron oxyhydroxides. Micro and macro-level movements of iron through soil minerals also begins to occur (Nahon 1986). Next, mottled clay layers are formed. Iron oxyhydroxides continue to migrate within the soil profile, becoming more crysta... ...69 - 190. - Oades, J. Malcolm, Gavin P. Gillman, and Goro Uehara with Nguyen V. Hue, Meine van Noordwijk, G. Philip Robertson and Koji Wada. " Interactions of Soil Organic Matter and Variable-Charge Clays" IN: " In: David C. Coleman, J. Malcolm Oades and Goro Uehara (eds.), Dynamics of Soil Organic Matter in Tropical Ecosystems: Hawaii, NifTAL Project University of Hwawii Press, 1989. p. 69 - 95. - Soil and Water Quality: An Agenda For Agriculture, Committee on Long-Range Soil and Water Conservation, Board on Agriculture., National Research Council: Washington D.C., National Academy Press, 1993. p. 218. - Soils and Soil Fertility, Frederick R. Troeh and Louis M. Thompson (eds.), New York, Oxford University Press, 1993. p. 311, 321 - 322. - Wambeke, Armand Van. Soils of the Tropics: Properties and Appraisal: New York, McGraw Hill Inc, 1992. p. 139 - 161.