Sodium affected subsoils,gypsum, and green-manure: Inter- actions and implications for amelioration of toxic red mud wastes |
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| Authors: | M A Harris P Rengasamy |
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| Institution: | (1) Department of History/Geography, Northern Caribbean University, Mandeville, Jamaica;(2) Department of Soil and Land Systems, School of Earth and Environmental Sciences, The University of Adelaide, 5005, South Australia |
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| Abstract: | Experiments were carried out on two alkaline sodium affected sub-soils (15–30 cm) from Strathalbyn and Two Wells in South Australia, under glasshouse conditions in pots containing 1 kg of soil. The effect of green manure was examined with and without the addition of gypsum. Before flowering, the common vetch (Vicia sativa) was incorporated into the soil, and incubated at 80% field capacity. After 12 weeks, the improvements in hydraulic conductivity (Ksat) occurred in the following order of treatments: gypsum+green manure >gypsum >green manure >control. Green manure did not improve macroaggregation in sodic soils. However, stabilisation occurred at the microstructure level. The average size of dispersed materials in control soils was <5  m, whereas after green manuring, the average particle size increased up to 30 m. The products of decomposition of green manure were both organic compounds and the released Ca2+ from native lime which aggregated the clay particles and stabilized the domains. The results of this study promise the use of green manure as an ameliorant for sodic alkaline environments such as the red muds of bauxitic minespoils. |
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| Keywords: | Bauxite minespoils Red muds Microaggregation Sodic soils Green manure South Australia |
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