Bulletin of the Geological Society of Malaysia, Volume 19, April 1986, pp. 469 – 480
*Department of Geology, University of Western Ontario, London, Canada N6A 5B7
**Department of Plant Sciences, University of Western Ontario, London, Canada N6A 5B7
Abstract: Studies of heavily leached lateritic soils from the Amazon Basin and Niger Delta regions show extreme removal of at least a dozen bio-essential elements. Macronutrients such as Na-K-Ca-Mg, present at the per cent level in fertile soils are often reduced to the ppm level in lateritic soils.
Western fertilizer technology was developed for fertile soils where enhanced levels of N-P-K cause significant increase in biomass production. For tropical soils the response is often small unless very massive fertilizer doses are used. Phosphate fertilizers carry a large array of trace elements and micronutrients (Ni, Zn, Mo, Ca, Mg) and plant response may often reflect these accidental additions as much as the phosphate influences. Phosphates also carry high levels of undesirable species such as uranium (typically at the 100 ppm level).
The weathering process and the influences of aerosol, ground water, and sea water fluxes will be considered as a function of time. Experiments will be described where mineral materials and mineral-based glasses have been tested as fertilizers on infertile soils. It will be shown that for such cases, higher biomass productivity has been produced using such materials than by use of conventional N-P-K. In fact, with soils of lower buffer capacity, soluble fertilizers can produce extreme toxicity, and environmental pollution. There is need for detailed field testing of all potential fertilizer materials to isolate the significant variables in sustained biomass production.