Impacts of the addition of biochar, biosolid and aluminum silicate on the leaching and bioavailability of 2,4-D + picloram in soil

Abstract The use of herbicides in high-yield crops is increasing, and their fate in the environment has become a primary environmental concern. The aim of this study was to evaluate the impacts of the use of biosolid, biochar, and aluminum silicate on the leaching dynamics of a mixture of 2,4-D + picloram herbicides, which is widely used in agricultural and non-agricultural areas. Three experiments were carried out, one for each residue, using the same methodological procedure. The tests were designed in randomized blocks with four replicates and split plots. Different proportions of the residues were incorporated in the pots at 0%, 10%, 20%, 30%, and 40% referring to the column volume, allocated in the subplots at different depths in the soil column (0–5, 5–10, 10–15, 15–20, 20–25, 25–30, 30–35, 35–40, and 40–45 cm). After the application of 2,4-D + picloram, 40 mm of rain was simulated in all columns. The plant bioindicator, Cucumis sativus, was sown in the profile. The increase in the biochar dose intensified 2,4-D + picloram leaching and grew C. sativus biomass in deeper layers of the soil profile. Regarding biosolids, an increased dose reduced the 2,4-D + picloram movement in soil and stimulated the growth of C. sativus. The addition of aluminum silicate to the soil did not influence the leaching of 2,4-D + picloram. However, it increased the biomass of C. sativus plants in the deeper layers of the soil profile. The addition of biosolids reduced the leaching of 2,4-D + picloram in the soil profile. However, the incorporation of biochar and aluminum silicate did not decrease the risk of contamination of the deeper layers of soil.