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Benefits of pulp sludge in agriculture

Farmers around Whitecourt and Slave Lake areas have been profiting greatly from what once thought of as “waste product” - mechanical pulp sludge produced by Alberta News Print Company (ANC), Millar Western Forest Products and Slave Lake Pulp (SLP). This is all thanks to the 20 years’ worth of research in the utilization of sludge lead by the Alberta Research Council (ARC) (now part of Alberta Innovates - Technology Futures) with support from the Mechanical Pulp and Paper Consortium Research Program.

Over the years many test plots have been established to evaluate the impact of single and multiple applications of sludge from different mills to obtain long term data relative to the impact on crop yields and soil quality. The benefits of sludge application on agricultural land have been overwhelmingly positive; turns out sludge not only acts like a slow release fertilizer but also provides many added benefits as a soil amendment.

In a project at the ANC Mayerthorpe site it was demonstrated that a one-time sludge application of 50 tonne of dry sludge/ha would yield in the same quality and quantity of barley as application of 200 kg/ha of 35-15-0 fertilizer annually over three years. Residual benefits from sludge were seen even after 5 years from initial sludge application. Sludge can supply a total of 15 to 30 kg N/tonne and most of the nitrogen in sludge exists in the organic form, and becomes available on a “slow release” basis. The cost savings associated with annual fertilizer application is significant for farmers who have access to pulp sludge.

Other beneficial aspects of sludge include the ability to improve soil structure and tilth and thereby increasing soil water holding capacity. Standards and guidelines for the land application of mechanical pulp mill sludge to agricultural land have been developed jointed by ANC, Millar Western Pulp, SLP, Alberta Environment and Water, Alberta Agriculture, Food and Rural Development and the ARC. Application rates and recommended standard practices were developed to ensure that sludge is used in an environmentally responsible manner.

For more information on the benefits of sludge in agriculture please go to www.SmartSludge.com.