Environmental technologies in paper industry are recognized as important tools in water pollution control andgenerate high quantities of paper mill sludges (PMS). Large PMS volumes has been used more and more inagriculture for almost five years in the province of Québec, reducing landfilling of these organic materials. In thepresent study, the agronomic potential and environmental impacts of PMS have been evaluated since 1997 in fieldexperiments in Central Québec on corn, soya and barley crops. Paper mill sludges were applied at rates varying from20 to 60 t/ha on wet basis, and compared to mineral fertilizer treatments and to a control without any fertilizer andPMS. Results indicated that PMS applied alone significantly increased corn and barley yields, compared to thecontrol treatment. Lower effects were observed on soya bean. Corn and barley highest yields were obtained whenPMS were combined with reduced fertilizer rates (50% to 75% NPKMg) leading to higher yields than thoseobtained with a complete fertilizer application (100% NPKMg). PMS effects on corn and barley yields were mainlydue to their high nutrient contents and efficiency and also to their significant effect on soil properties. PMSsignificantly increased soil microbial biomass, microbial respiration (CO2), nitrogen mineralization (NO3-) as wellas phosphatase and urease activities. PMS applications also increased soil organic matter content and earthwormabundance (data not presented). Results also indicated that three successive PMS applications did not increase soilmetal content (Ni, Cr, Co, Cu, Cd and Pb) in the 0-40 cm soil layer, as a result of their low contents in thoseconstituents. Results on E.coli and coliforms also showed lower populations in soil treated with PMS, compared tothe control and mineral fertilizer treatments. From this point of view, PMS could be considered safe for use inagriculture when they meet environmental standards. Due to their high nutrient and organic matter contents, PMSare recommended as fertilizers and organic amendments for a sustainable agriculture.
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