Characterization of organic matter from animal manures after digestion by earthworms
The humification index (HI) values of three different manures and earthworm casts were calculated for three different extractant solutions (0.5M sodium hydroxide, 0.1M sodium pyrophosphate pH 7 and 0.1M sodium pyrophosphate plus 0.1M NaOH). The alkaline sodium pyrophosphate solution was found to be the most suitable because of both its extraction efficiency and the quality of the organic matter extracted which allows a good characterization of the stabilization degree attained by composting. Neutral sodium pyrophosphate extracts also show characteristic HI values for different samples but lower extraction efficiencies. The HI values for sodium hydroxide extracts show only little differences between manures and composts. The good correspondence found between HI data and isoelectric focusing (IEF) patterns confirmed on one side that humification indexes give a quantitative measure of the humification degree, on the other side that IEF is a suitable technique in order to obtain qualitative informations on organic matter stabilization in earthworm casts.
Key wordsextraction numification index isoelectric focusing organic matter worm cast
Unable to display preview. Download preview PDF.
- De Nobili M, Cercignani G and Leita L 1984 Evaluation of type and contents of humic substances in sludges and compost.In Long-Term Effects of Sewage Sludge and Farm Slurries Applications. Elsevier Applied Science Publishers, London, pp 204–209.Google Scholar
- De Nobili M, Cercignani G, Leita L and Sequi P 1986 Evaluation of organic matter stabilization in sewage sludge. Commun. Soil Sci. Plant Anal. 17, 1109–1119.Google Scholar
- Roletto E, Barberis R, Consiglio M and Iodice R 1985 Chemical parameters for evaluating compost maturity. Bio-Cycle 26, 46–47.Google Scholar
- Schnitzer M, Lowe L E, Dormaar J F and Martel V 1981 A procedure for the characterization of soil organic matter. Can. J. Soil Sci. 61, 517–519.Google Scholar
- Sequi P, De Nobili M, Leita L and Cercignani G 1986 A new index of humification. Agrochimica 30, 175–179.Google Scholar