These are some areas in which additional research is needed. It is important to recognize that different soils, crops, sludges and sludge products will respond differently so that research results will vary depending on these and other variables. Research should be supported through an entity that is independent of the sludge stakeholders. Analyze the temporal variability of quality and nutrient content of sludges from individual WWTPs.
Quality varies significantly from sample to sample.
Farmers and their advisors apply based on monitoring results not obtained from the particular sludge load being delivered and may thus over or under apply nutrients. Particularly viruses leaching from Class B sludges. What are the likely exposures and impact of those exposures to the dairy farm family. Also need to evaluate the potential for acute toxicity from one-time high ingestion days.