Dinâmica de picloram + 2,4-D sob influência de biochar, biossólido e silicato de alumínio no solo

Abstract

Auxin mimic herbicides promote the control of eudicotiledonous plants, but they are susceptible to leaching and intoxication of non-target organisms. The objective of this study was: 1 to evaluate the leaching of picloram + 2,4-D applied in soil incorporated with different doses of thermally treated biosolids, biochar from eucalyptus pyrolysis and aluminum silicate, 2- to analyze the sorption of the herbicidal mixture in the same residues. The first study was installed in a greenhouse, the biochar, biosolid and aluminum silicate residues were incorporated into the soil and conditioned in PVC columns. Five proportions of the residues, 0, 10, 20, 30 and 40% of the profile volume were tested, subsequently was done herbicide application and sown Cucumis sativus as a bioindicator species. The second study was carried out in the field, where the biosolids and biochar were incorporated in the planting in 5 doses 0, 5, 10, 15 and 20% of the volume of the pit. Already, the aluminum silicate was tested in 5 proportions 0, 1, 2, 3 and 4 kg/ pit. The same residues were also tested in a simultaneous experiment on the surface of the pits, in slides of 0.9, 1.8, 2.7 and 3.6 dm³/ pit. After addition of the residues was carried out the application of picloram + 2,4-D in the dose of 5 L ha-1. Two eucalyptus plantations were performed at 30 and 68 days after application. The residues influenced in herbicide leaching. The increase in the proportion of biochar in the soil promoted increased leaching, while addition of biosolids reduced leaching. The biomass of the plants was higher in the deeper layers in the higher dose of biochar and aluminum silicate, and in intermediate layers in the use of biosolids. In the second study both biosolid and biochar applied on the surface provided increase in leaf area, photosynthetic rate and water use efficiency of the eucalyptus seedlings. Biochar provided an effective reduction in intoxication when applied to the surface. The use of biosolids reduces the leaching of picloram + 2,4-D in the soil, and the application of biochar in surface reduces the risk of intoxication of this mixture for eucalyptus cultivation.