LAUSR

Abstract Eucalyptus globulus Labill. (Tasmanian blue gum), one of the most widespread wood species, is broadly grown in forestry exploitations for timber production, giving rise to abundant harvest residues devoted to obtaining bioenergy or essential oils. However, considering the need for searching new environmentally friendly strategies for weed control, a question arises: ‘would remnants of pruning and logging from eucalyptus plantations be processed and used as a green manure with herbicidal potential in agricultural fields?’ After the evident allelopathic nature of E. globulus and the phytotoxic effects observed from our previous in vitro and greenhouse studies, it is time to address the actual ability of eucalyptus residues for weed control under field conditions. In this study, the potential of E. globulus leaves for weed control was approached by field experiments conducted in weed-infested maize fields, during two growing seasons and at two different locations. Significant reductions were observed on the biomass of the dominant problematic weed species Digitaria sanguinalis (L.) Scop. and Chenopodium album L. up to 69.5 and 88.5% relative to control plots, respectively, together with general effectiveness for weed control throughout the experiments. Concomitantly, maize was not negatively affected by eucalyptus green manure. The phytotoxic effects on weeds were more significant at early stages of maize establishment since weed biomass was reduced from ca. 38–80% relative to control plots, thus alleviating weed-crop competition. Additionally, eucalyptus green manure increased pH, CECe, exchangeable cations Ca2+, Mg2+, and K+, and microbial biomass carbon, as symptoms of enhanced soil quality. Our results demonstrate that the incorporation of E. globulus harvest residues into the soil as a green manure can be a feasible and environmentally friendly practice for field weed control in organic maize-based cropping systems.