Pre- and post-mined bauxite soils of Jamaica: physical and chemical properties.

摘要

Earthy bauxite (aluminium ore) deposits over limestone bedrock cover over 20% of Jamaica's surface area. With the shortage of arable land in Jamaica, there is great interest in using post-mined bauxite lands for agriculture. The purpose of this study was to compare physical and chemical properties of pre- and post-mined bauxite soils that are relevant in assessing suitability of these lands for small-scale agriculture. Pedons were described and sampled for characterization at two pre-mined sites and four post-mined sites near Mandeville, Jamaica. Post-mined soils were generally steeper, shallower, and higher in limestone rock fragments than pre-mined soils. Pre-mined soils consisted of Ap and Bo horizons making up clayey Oxisols with low charge and low bulk density. The new caret (^) symbol, which indicates horizons formed from human transported material, was helpful in describing pedons of post-mined soils. Post-mined soils consisted of ^Ap horizons (replaced topsoil) and 2^C horizons (fill material) over limestone. Some post-mined pedons also had 2Bob or 3Bob horizons (Bo in situ buried by replaced topsoil and/or fill material). Post-mined soils had higher bulk density in the ^Ap horizons than pre-mined Ap horizons and higher pH throughout due to the incorporation of limestone rock fragments. In ^Ap horizons, organic matter and granular structure increased with time after reclamation and establishment of grass cover..