Effects of composting on phytotoxicity of spent pig-manure sawdust litter.

The phytotoxicity of spent pig-manure sawdust litter (spent litter) was evaluated during further composting. Aqueous extracts of the spent litter were prepared by shaking the sample with water (1:10 w/v), and the toxicity of these extracts was determined on relative seed germination, relative root elongation and germination index (GI, a factor of relative seed germination and relative root elongation). The sensitivity of six plant species, namely Brassica parachinensis (Chinese cabbage), Brassica albogalera (Chinese kale), Allium sativum (onion), Cucumis sativus (cucumber), Amaranthus espinosus (Chinese spinach), and Lycopersicon esculentum (tomato) were compared. The effect of different moisture levels during composting on the phytotoxicity of the spent litter was also examined. Phytotoxicity of the spent litter was only evident during the earlier stage of composting (first 14 days) and, that seed germination and root elongation reached 100% (same as the control) towards the end of the composting. The concentrations of the major inhibitors, water-extractable Cu and Zn, and NH4(+)-N of the spent litter, declined during composting, indicating that these inhibitors were gradually eliminated as composting proceeded. Multiple regression analysis showed that the NH4(+)-N content of the spent litter was the most important chemical factor affecting phytotoxicity of the plant species selected for this study. Relative root elongation and GI were more sensitive indicators of phytotoxicity than seed germination. In the present study, the GI's of all plant species were >80% at day 60, indicating that the spent litter had reached its maturation by day 60. The responses of different plant species to the water-extracts of the spent litter were different. Among the six species, Chinese cabbage and Chinese spinach were the most sensitive species, and tomato and cucumber were the least sensitive species to indicate phytotoxicity of the spent litter. Moisture adjustment during the composting process did not affect the results of the phytotoxicity test.

[1]  Harry A. J. Hoitink,et al.  NEW APPROACHES TO COMPOST MATURITY , 1990 .

[2]  R. W. Pearson,et al.  Toxicity of Decomposing Crop Residues to Cotton Germination and Seedling Growth1 , 1967 .

[3]  J. O’grady,et al.  Copper supplementation of pig diets. The effect of protein level and zinc supplementation on the response to added copper , 1968 .

[4]  S. M. Tiquia,et al.  Assessing toxicity of spent pig litter using a seed germination technique , 1994 .

[5]  L. Vrijmoed,et al.  Effects of Commercial Bacterial Products On Nutrient Transformations of Pig Manure in a Pig-On-Litter System , 1990 .

[6]  Wun-cheng Wang,et al.  Comparative seed germination tests using ten plant species for toxicity assessment of a metal engraving effluent sample , 1990 .

[7]  F. C. Miller,et al.  Biodegradation of Solid Wastes by Composting , 1997 .

[8]  A. M. Martin,et al.  Biological degradation of wastes , 1991 .

[9]  David P. Chynoweth,et al.  Biogasification of processed MSW , 1990 .

[10]  Mitsuyo Hirai,et al.  Changes of Chemical Components and Nitrogen Transformation in Water Extracts during Composting of Garbage , 1982 .

[11]  J. Morel,et al.  Methods for the evaluation of the maturity of municipal refuse compost , 1985 .

[12]  F. Zucconi,et al.  Biological evaluation of compost maturity , 1981 .

[13]  M. de Bertoldi,et al.  Evaluating toxicity of immature compost , 1981 .

[14]  M. Wong.  Effects of animal manure composts on tree (Acacia confusa) seedling growth , 1985 .

[15]  A. Wild,et al.  Russell's Soil Conditions and Plant Growth , 1988 .

[16]  M. W. Adams,et al.  Differential Response of Navy Beans (Phaseolus vulgaris L.) to Zinc. I. Differential Growth and Elemental Composition at Excessive Zn Levels1 , 1970 .

[17]  A. Monaco,et al.  Phytotoxins during the stabilization of organic matter , 1985 .

[18]  I. J. Hodgkiss,et al.  Effect of Moisture Content on the Composting of Pig-Manure Sawdust Litter Disposed From the Pig-on-Litter (POL) System , 1996 .

[19]  J. Coombs.  Composting of agricultural and other wastes: Edited by J. K. R. Gasser. 1985. Elsevier Applied Science Publishers, London and New York. x + 320 pp. ISBN 0-85334-357-8. Price: £38.00 , 1986 .

[20]  P. Sequi,et al.  Evaluation of heavy metals during stabilization of organic matter in compost produced with municipal solid wastes , 1993 .

[21]  O. Verdonck,et al.  Phytotoxicity of olive tree leaf compost in relation to the organic acid concentration , 1989 .

[22]  T. McNeilly,et al.  EVOLUTIONARY PROCESSES IN POPULATIONS OF COPPER TOLERANT AGROSTIS TENUIS Sibth. , 1968, Evolution; international journal of organic evolution.

[23]  A. Page.  Methods of soil analysis. Part 2. Chemical and microbiological properties. , 1982 .

[24]  J. Molina,et al.  Aeration-Induced Changes in Liquid Digested Sewage Sludge1 , 1971 .