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ALUMINUM DETOXIFICATION WITH GREEN MANURES
N.V. Hue and I. Amien
Commun. In Soil Sci. Plant Anal. 20: 1499-1511 (1989)
A greenhouse experiment was conducted to evaluate "liming" potential of different green
manures. Ground leafy materials of cowpea (Vigna unguiculata), leucaena (Leucaena
leucocephala) and guinea grass (Panicum maximum) were added at 0, 5, 10 and 20 g/kg
to an Ultisol having a soil-water pH 4.0, Kcl-extractable Al = 7.6 cmolc/kg, Al
saturation = 50% and soil-solution Al = 2.2 mM. Treatments with Ca(OH)2 were
established for comparison. Sesbania cochinchinensis, an Al-sensitive tree legume, was
grown for 4 weeks as a test crop. Biomass production and chemical composition of the
soil indicated that (i) cowpea and leucaena were more effective than guinea grass in
detoxifying Al; for example, the additions of 10g manure per kg soil were equivalent to 1.8
cmol(OH)/kg for guinea grass, 3.4 for cowpea and 4.2 for leucaena (at least on a short-term basis), (ii) reduction of soluble Al at increased pH as a result of manure additions was
the major mechanism for Al detoxification, and (iii) complexation of soluble Al by organic
molecules also contributed to the detoxification.
For more information regarding this page, please send e-mail to nvhue@hawaii.edu.
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