Nitrogen availability from poultry processing plant DAF sludge

Nitrogen is typically the load-limiting factor in applying poultry processing dissolved air flotation sludge to land. The amount of land required for sludge application is greatly affected by the estimated plant available portion of the total nitrogen. Laboratory aerobic (24-wks) and anaerobic (1-wk) incubations conducted as biological indices of nitrogen availability generally indicated ranges of available N of about 30-40% and 40-50%, respectively, of the sludges' total nitrogen. Potted-plant studies with corn and one soil type indicated nitrogen uptake from sludge was about one third of that from ammonium nitrate fertilizer. No deleterious germination effects were noticeable when corn was planted one week after sludge application.