Use of Paper De-inking Residues in Potato Production

in HortScience
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  • 1 Centre de Recherche en Horticulture, Departement de Phytologie, FSAA, Université Laval, Qué. G1K 7P4, Canada

In 1991, a project was initiated in collaboration with the Daishowa paper company to characterize de-inking residues resulting from paper recycling in detail and to determine the value of this organic residue as an amendment to agricultural soils. Our objective was to determine the effects of field applications of de-inking residues on potato crop culture. In 1992, 1993, and 1994, experimental plots were established and maintained at the Horticultural Experimental Farm of Laval Univ. A factorial design was composed of four replications of four doses of de-inking residues (0, 15, 30, and 45 t·ha–1) combined with four doses of N (0, 45, 90, and 135 kg·ha–1). Treatments were applied to a total of 64 plots. The results indicate the importance of adjusting the fertilization to prevent the immobilization of N by the residues. In 1992, as a result of adding de-inking residues, potato yields were increased significantly when sufficient N fertilizer was added. However, significant decreases in yield were noted when a high level of de-inking residues was applied without any adjustment of the C:N ratio. In 1993, potato yields were reduced in treatments having a second application of residue at the highest doses (30 and 45 t·ha–1), even when additional N was provide. Interestingly, harvested tubers gave no indication of toxicity effects due to heavy metals or other contaminants. Results also will be discussed in terms of overall potato quality and the incidence of disease.