The pulp and paper industry produces deinking sludge, a waste by-product rich in organic matter andpotentially beneficial to agricultural soils. Field experiments were performed with deinking sludgeand a mix of deinking and secondary (combined) sludge to measure the environmental impactassociated with landspreading. Treatments consisted of three application rates of deinking (6, 12, and18 dry t/ha) or combined sludge (8, 16, and 24 dry t/ha) associated with three rates of supplementarymineral nitrogen fertilizer and a control plot. Chemical analyses of deinking and combined sludgeindicated that no organic and inorganic contaminants were present at problematic levels, except forcopper (191μg/g). Soil monitoring of the nutrients and heavy metals in experimental plots showedno significant difference (p = 0.05) between sludge treatments and the control after two years ofsludge application. Monitoring of nitrate in the soil water indicated a linear relationship (p≤ 0.08)with the additional nitrogen level. High sludge and low nitrogen application rates were associated withreduced nitrate concentration in the soil water. Detrimental environmental effects were not observedwith deinking and combined sludge. Compared to the control. potato yield tended to decrease withdeinking and combined sludge applications while barley yield increased with combined sludgeapplications.
展开▼
