Measurement of total phosphorus and organic phosphorus contents of animal manure composts by the dry combustion method
2003
Yokota, T. (Tohoku Univ., Sendai (Japan)) | Ito, T. | Saigusa, M.
The objective of this paper was to determine the optimum ignition temperature to measure precisely the total and organic P contents of animal manure composts by the dry combustion method. Total P content of the composts was measured by the wet digestion method and the dry combustion method, while the organic P content was measured by the fraction-ation method and the dry combustion method. Total P content of the composts ranged from 4.43 to 48.6 g kg sup(-1) and there were significant correlations between the total P content mea-sured by the wet digestion method and that measured by the dry combustion method at 550 deg C. Organic P content measured by the fractionation method ranged from 0.44 to 8.62 g kg sup(-1). Organic P content measured by the dry combustion method ranged from 0.10 to 8.63 g kg sup(-1), and there were significant correlations (r = 0.951) between the data obtained by the fractionation method and those obtained by the dry combustion method at 550 deg C. Ignition at 240 and 350 deg C was insufficient to completely decompose the organic matter, and resulted in the underestimation of the total and organic P contents of the composts. The proportion of organic P in all the compost samples ranged from 0.54 to 46%. Based on these results, we concluded that 550 deg C was the optimum ignition temperature for a precise deter-mination of the total and organic P contents of animal manure composts by the dry combustion method.
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