Retention of pendimethalin by humic acids from different farm wastes and by soils in various management systems

Abstract

The retention of pendimethalin by humic acids (HAs) from different farm wastes and from soils in various management systems was studied at 20 and 40°C. The magnitude of pendimethalin retained varied from 19.50–71.00 and 20.50–80.00 μM g −1 at 20°C on HAs from farm wastes and soils, respectively, which decreased with a rise in temperature. Pendimethalin retention followed the order: Soil HAs > Farm waste HAs. The highly significant values of R 2 suggested the excellent fitness of the Freundlich (0.965**–0.996**) and Langmuir (0.943**–0.986**) isotherms for pendimethalin retention. The values of the ‘k’ and ‘n’ retention parameters of the Freundlich isotherm and the ‘K’ and ‘b’ parameters of the Langmuir equation confirmed the relatively higher capacity of soil HAs to retain pendimethalin.