Effect of Al and Fe on decomposition of organic fertilizers
1991
Patcharee Saenjan (Khon Kaen Univ., Khon Kaen (Thailand). Faculty of Agriculture. Dept of Soil Science) | Duangsamorn Taja | Ketsuda Dejbhimon
Experiment was conducted to study effect of metal ions (Al and Fe) on decomposition of organic fertilizers: buffalo dung, city compost and rice straw compost. Polyhydroxy aluminum chloride (PAC), AlCl3 and FeSO47H2O were used as sources of Al and Fe. The dose of the added metal was equivalent to CEC of organic fertilizer. Mixture of metal and organic fertilizer was incubated under aerobic condition for 3, 7, 14 and 28 days. Carbon dioxide emission was represented as microbial decomposition of organic fertilizer, pH, optical density (OD), amount of Al and Fe of organic-fertilizer-KCl extract and fractionation of water-soluble-metal-organic compound were analyzed. Metal compounds reduced decomposition of buffalo dung and rice straw compost through mechanism of chelation. This formation of metalic organic complexes was resistant to microbial decomposition under incubated condition. Bondage between metal ions may be very weak for the water-soluble organic compounds, somewhat strong for the hemicellulose and cellulose. Moreover, formation of metal organic complexes was suggested to be hydroxy Al and hydroxy Fe combined with humic and fulvic substances existing in organic fertilizers. Further research with various kinds of organic fertilizers and metal compounds should be conducted in a similar manner, especially, to infertile soil of northeast, Thailand, which has low organic matter content and poor physical property.
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