Fertilization using sewage sludge in unfertile tropical soils increased wood production in Eucalyptus plantations.

Fertilization of Eucalyptus plantations using sewage sludge on unfertile tropical soils represents an alternative to using mineral N and P fertilizers. A 44-month field experiment was conducted to study the effects of increasing application of sludge, and its interactions with mineral N and P fertilizers, on wood volume. Four rates of sludge (0, 8, 15 and 23 Mg ha, dry base), N (0, 47, 95 and 142 kg ha) and P (0, 28, 56 and 84 kg ha of PO) were combined in a 4 × 4 × 4 factorial scheme in a totally randomized block design.