Accelerated Dissipation of Two Herbicides after Repeated Application in Field Experiments with Organically-Amended Soil

Organic wastes applied as composted amendments may improve the quality of degraded soils and modify fate pesticides. This work has set out to study dissipation kinetics herbicides chlorotoluron flufenacet during their second-year application in field experimental plots with a sandy-loam agricultural soil without amendment (S) amended spent mushroom substrate (S + SMS) or green compost GC). The SMS GC were previous winter’s wheat crop campaign (1 year before second herbicide application) at rates 140 85 t ha−1 (dry weight basis), respectively. experiment involved randomized complete blocks 81 m2, including three replicates per treatment. Surface sampled after for 225 days, residues samples determined by HPLC-MS. curves both treatments better fitted first order multi-compartment (FOMC) kinetic model. most hydrophobic herbicide, flufenacet, slower than those unamended soils. half-life (DT50) values ranged between 20.7 41.1 days chlorotoluron, 42.9 75.6 they followed S > GC. DT50 close GC, was similar that SMS. These decreased up four times respect calculated indicating an accelerated especially comparison soil. persistence modified effect organic amendments, weather conditions, possibly repeated compounds under real conditions.