Modulating Leaching Behavior of Boscalid Fungicide in Soil Through Organic Amendments.

The leaching loss and movement of pesticides need to be minimized to safeguard the aquatic environment and human health. In a laboratory study, the changes in the leaching and downward movement behavior of boscalid fungicide were examined in soil (Typic Hapludoll) columns (0–30 cm) receiving no amendment (control) or with the application of farmyard manure (FYM) and pine needle biochar (PNB) in surface (0–15 cm) soil @ 5 t ha−1. No boscalid residues (<0.01 µg mL−1) were detected in the leachate under any treatment. Both FYM and PNB were effective in limiting the movement of boscalid in soil compared to control. FYM maintained the highest boscalid concentration (1.41 µg g−1) in the top (0–2.5 cm) soil while in PNB treated soil the highest sorbed boscalid (0.58 µg g−1) could accumulate at 2.5–5.0 cm soil depth. The depth-wise distribution of the boscalid concentration in soil could be well predicted by third order polynomial equations (R2 value = 0.929 to 1.000, all significant at p ≤ 0.01). The FTIR spectra show that the boscalid retention onto these amendments was through H-bonding and π–π interactions. As compared to FYM, the PNB had a relatively lower proportion of soluble- and desorbed-boscalids but a higher proportion of irreversibly sorbed boscalid and appeared to be an effective organic amendment for the areas prone to high surface run-off. [ABSTRACT FROM AUTHOR]