Paper recycling residue application in acid soil: I – Fertility and heavy metal levels in the soil

Abstract

The paper recycling process generates an expressive amount of residue and in general the disposal of this product in landfills is economically impracticable. An alternative is its application in the soil, with the aim to
increase the soil pH and the Ca level. However, there are heavy metals in this residue, making it necessary to study the agronomic and environmental effects of the residue application in the soil. The objective of this study was to evaluate the effects of the application of paper recycling residues in different doses on soil chemical properties. An
experiment was carried out in Papanduva, Santa Catarina, southern Brazil, in a complete randomized block design, with three replications. These were the evaluated doses of paper recycling residues: 64, 127, 191, 254, 382 and 509t/ha of wet mass. In addition, a treatment with lime and a test without residues or lime application were evaluated.
The residues and lime were incorporated in the zero to 20cm soil layer, through one ploughing and three diskings, in winter time (June 2004). After residue incorporation in the soil, the no-tillage system was used. The soil samples were collected 9, 22, and 34 months after application, in the zero to 20cm layer. The residue application increased soil pH and Ca levels, and the Ca/Mg relation in the soil. The Hg, Pb, Ni, Cd and Cr levels in the soil were not affected by residues, even in greater doses.