The effects of digested sludge application on the chemical composition of soil, plant, and water samples from a large field lysimeter facility are discussed. Specific hygienic aspects of digested sludge were also investigated and, it was found that viruses are not likely to survive the heated anaerobic digester environment and, although digested sludge contains large populations of fecal coliform bacteria, these organisms die away rather rapidly during storage and after spreading on the soil. Results from green house and field studies indicate that several crop plants show favorable growth responses when fertilized with digested sludge, however, concentration levels of several chemical elements in soils are increased above native amounts and are also increased in plant tissues. As long as digested sludge application rates do not exceed those which will result in unacceptable concentration levels of NO3-N in drainage or groundwaters, sludge of the quality employed in the study can be safely used to increase the production of good quality crops.

"PB-236 402." "An environmental protection publication in the solid waste management series (SW-30d.1)." Includes bibliographical references (pages 358-370).