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Title: CHEMICAL-MEDIATED TOXICITY OF N-VIRO SOIL TO HETERODERA GLYCINES AND MELOIDOGYNE INCOGNITA

Author
item Zasada, Inga
item TENUTA, MARIO - UNIV MANITOBA, CANADA

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2004
Publication Date: 9/1/2004
Citation: Zasada, I.A., Tenuta, M. 2004. Chemical-mediated toxicity of n-viro soil to heterodera glycines and meloidogyne incognita. Journal of Nematology 36:297-302.

Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack plants and cause ten billion dollars in crop losses annually in the United States. Farmers face an enormous problem because they lack safe and effective ways of reducing the numbers of nematodes in soils. Therefore, in this study, two agriculturally destructive species of nematodes were exposed in laboratory tests to a novel product designed for application to soils. This product, called N-Viro Soil, is formed from municipal sewage treatment wastes that have been freed of human disease organisms through a sanitization and stabilization process. Following N-Viro Soil application, scientists monitored plant-parasitic nematode death and changes in soil chemistry. An increasing number of nematodes were killed with increasing rates of N-Viro Soil. The incorporation of N-Viro Soil into sand resulted in a rapid increase in soil alkalinity and concentrations of calcium, sulfur and ammonium. The increase in soil alkalinity was the event most closely related to nematode kill. To a lesser extent, the increased concentrations of ammonia were also responsible. These results are significant because they provide the first identified chemical factors that are partly responsible for the toxicity of N-Viro Soil to nematodes. This research will be used by scientists to enhance the ability of N-Viro Soil to reduce nematode numbers in agricultural fields.

Technical Abstract: N-Viro Soil trade mark (NVS) is an alkaline-stabilized municipal biosolid that has been shown to lower densities and reduced egg hatch of Heterodera glycines and other plant-parasitic nematodes; but the mechanism(s) of nematode suppression of this soil amendment are unknown. This study aimed to identify NVS-mediated changes in soil chemical properties and their impact upon H. glycines and Meloidogyne incognita mortality. NVS was applied to sand in laboratory assays at 0.5, 1.0, 2.0 and 3.0% dry w/w with a non-amended treatment as a control. Nematode mortality and changes in sand-assay chemical properties were determined 24 hours after incubation. Calculated lethal concentration (LC90) values were 1.4% w/w NVS for juveniles of both nematode species and 2.6 and > 3.0% w/w NVS for eggs of M. incognita and H. glycines, respectively. Increasing rates of NVS were strongly correlated with higher sand solution pH levels. Sand solution pH levels, and to a lesser extent, the production of ammonia, appear to be the chemical-mediated factors responsible for killing plant-parasitic nematodes following amendment with NVS.