Nitrogen Availability From Applying Pulp and Papermill Sludge, 1997 Environmental Conference Proceedings

The land application of papermill wastewater sludge is increasing in popularity as an accepted method for recycling nutrients from the sludge. Because farmers receiving the sludge are depending on the nutrients contained in the sludge for crop production, an accurate means of assessing the available nitrogen is essential. To make this assessment, an approximately 1.14 ha plot was divided into 25 subplots in a fertilizer to sludge matrix. Papermill sludge from Champion’s Quinnesec, Michigan mill was applied to the subplots at rates of 0 to 44.8 MT per ha. Nitrogen was applied at rates of 0 to 168 Kg per ha to the subplots receiving sludge and the plot was planted to Ryegrass. Plant samples were collected midway through the growing season and again prior to harvest and were analyzed for nutrients and selected metals. Soil samples were taken from 0-15 cm and 15-30 cm and analyzed for nutrients and selected metals. Based on the results an appropriate sludge application rate was calculated which took into consideration nitrogen immobilization, fertilizer requirements, yield and nitrogen movement through the soil.