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The use of green waste compost in peat-based potting mixtures: Fertilization and suppressiveness against soilborne diseases
Twelve commercially produced Dutch green waste composts were evaluated for their suitability to replace 20% (v/v) peat substrate in the cultivation of ornamentals. Salt concentrations were determined in water extracts of the composts and disease suppressive effects were assessed against various soil...
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Published in: | Scientia horticulturae 2007-11, Vol.114 (4), p.289-297 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
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Summary: | Twelve commercially produced Dutch green waste composts were evaluated for their suitability to replace 20% (v/v) peat substrate in the cultivation of ornamentals. Salt concentrations were determined in water extracts of the composts and disease suppressive effects were assessed against various soilborne diseases. The Cl-concentration of the compost extract appeared to be the limiting factor for use of the composts in potting mixtures. The Cl-concentrations in 7 and 1 composts, respectively, were too high to replace 20% of peat for growing salt sensitive and moderately salt sensitive plants, according to guidelines set for these groups of plants. The suppressive effects of the composts were tested in peat-based potting mixtures using three bioassays:
Phytophthora cinnamomi—lupin,
Cylindrocladium spathiphylli—
Spathiphyllum and
Rhizoctonia solani AG2-1—cauliflower. Disease levels in compost-amended mixtures were compared with the non-amended controls. None of the composts induced suppressiveness against
P. cinnamomi; 3 and 9 composts significantly induced suppressiveness against
C. spathiphylli and
R. solani, respectively. No significant disease enhancement was observed in any of the bioassays. The pH of the potting mixture showed a negative correlation with suppression of the
Rhizoctonia disease (
R
2
=
0.56). The effect of pH (pH 4–6) on suppression of
R. solani and
P. cinnamomi was further studied in non-amended peat. Disease suppression of
R. solani in cauliflower decreased with increasing pH in two different kinds of peat, while there was no effect on
P. cinnamomi. The suppressive effect of 3 composts was assessed in two experiments against
Fusarium wilt in
Cyclamen persicum (caused by
F. oxysporum f. sp.
cyclamini) and
Begonia eliator (caused by
F. foetens) under near-commercial conditions. None of the composts had a significant effect on
Fusarium wilt in
Cyclamen. Two and 3 composts significantly induced suppressiveness against
Fusarium wilt in
Begonia in the first and second experiments, respectively. No significant differences were observed in growth characteristics between
Begonia plants grown in compost-amended and non-amended potting mixture in both experiments. In the second experiment,
Cyclamen plants grown in compost-amended potting mixture had significant lower number of flowers than plants grown in non-amended potting mixture, which may have been due to lower concentrations of N in the compost-amended potting mixtures. In conclusion, most c |
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ISSN: | 0304-4238 1879-1018 |
DOI: | 10.1016/j.scienta.2007.06.018 |