Impact of Deinking Sludge Amendment on Agricultural Soil Quality, 1996 Environmental Conference Proceedings

In 1992, Daishowa Inc. and Université Laval initiated a five year research project to study the agricultural use of organic residues from the Daishowa deinking plant, in Quebec, Canada. Since a detailed chemical characterization had revealed that deinking sludge was unlikely to result in soil contamination, a study was initiated on the possible use of the deinking sludge for field application. Deinking sludge (C/N of 344) was added onto a silty loam soil under potato production in May 1992 and 1993. Field trials consisted of 16 different combinations of treatments: 0, 6, 12, and 18 dry t/ha of deinking sludge were combined to 0, 45, 90 and 135 kg/ha of supplemental nitrogen fertilization. The supplemental nitrogen was added to the 135 kg-N/ha usually applied fertilization, to compensate for the sludge nitrogen immobilization effect. Chemical and physical parameters were analyzed to determine the impact of deinking sludge amendment on soil quality. Results indicated that pH, electrical conductivity, soil fertility (P, K, Ca, and Mg), heavy metals, plant available water and soil bulk density were not influenced by the amendment between 1992 and 1994. Soil organic matter increased by 1% with the highest application rate, but these increases had disappeared by 1994, after amendment had stopped. Soil structural stability, a parameter linked to soil erodability and soil crust formation, was the most affected soil parameters by deinking amendment. It increased up to 20% in 1993, after two applications, but the beneficial effect disappeared as the amendment stopped in 1994. Crop yields were followed...