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Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/28/2004 Publication Date: 6/1/2005 Citation: Zasada, I.A. 2005. Factors affecting the suppression of heterodera glycines by n-viro soil. Journal of Nematology 37:220-225. 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. N-Viro Soil is formed from municipal sewage treatment wastes that have been freed of human disease organisms through a sanitization and stabilization process. A previous study found that when two agriculturally destructive species of nematodes were exposed to N-Viro Soil, they were killed. In this study several factors that could influence the use of N-Viro Soil as a nematode management tool were addressed. Stabilization of sewage waste was necessary to kill nematodes. N-Viro Soils from different processing facilities resulted in similar nematode mortality and have the potential for widespread implementation. Microbes associated with N-Viro Soil appeared not to be responsible for the nematode mortality observed by this product. This study confirmed the previous finding that the increase in soil alkalinity was the event most closely related to nematode kill. These results are significant because they indicate that N-Viro Soil can be utilized as a nematode management tool nationally. This research will be used by scientists to enhance the ability of N-Viro Soil to reduce nematode numbers in agricultural fields. Technical Abstract: Previous laboratory research demonstrated that N-Viro Soil (NVS), an alkaline-stabilized municipal biosolid, suppressed plant-parasitic nematodes. This study continued to explore the use of NVS as a nematode management tool specifically addressing factors that could influence its use. NVS from different locations, the components of NVS, dewatered biosolids and fly ash admixtures, and sterilized NVS were applied to soil microcosms, and nematode survival and changes in sand solution pH and ammonia were measured. This study confirmed the previous finding that an important mechanism of H. glycines suppression by NVS was the generation of alkaline soil conditions. Only the fly ash admixture that resulted in an increase in pH to 10.0 suppressed H. glycines to the same level as NVS. Alkaline-stabilization of biosolids was necessary to achieve nematode suppression. Biosolids applied at rates < 3% dry w/w did not suppress H. glycines to the same level as equivalent amounts of NVS. Sand solution pH levels after biosolid application, regardless of rate, were approximately 8.5 while 1 and 4% w/w NVS amendment resulted in pH levels of 10.3 and 11.6, respectively. The generation of ammonia after biosolid application was an important factor in nematode suppression. NVS from different processing facilities have the potential for widespread implementation. The NVS source that produced the highest concentration of ammonia did not reduce H. glycines survival to the same level as those sources generating pH levels above 10.1. Microbes associated with NVS appeared not to be responsible for the nematode suppressiveness of the amendment; there was no difference in nematode suppression between autoclaved and unautoclaved NVS. |
