Effect of Organic Amendments on the Retention and Mobility of Imazaquin in Soils

Abstract

The influence of two organic amendments consisting of an urban waste compost (SUW) and a commercial amendment from olive mill wastes (OW) was assessed on the sorption properties and leaching of the ionizable herbicide imazaquin on four soils with different physicochemical characteristics. A loamy sand soil (CR), a loam soil (P44), a silt loam soil (AL), and a clay soil (TM), with low-medium organic matter contents, were chosen. Sorption-desorption experiments were performed on the original soils and on a mixture of these soils with the organic amendments at a rate of 6.25% (w/w). These mixtures were used just after preparation and after aging for 3 months. Imazaquin adsorption was higher on AL soil because of its high content of amorphous iron oxides, whereas it was related to the soils' organic matter (OM) contents on TM and CR soils and to acid pH on P44 soil. Addition of exogenous OM to soils caused a decrease in the adsorption of the herbicide with the only exception of CR soil, due to blocking of adsorptive surfaces and/or equilibrium pH rise. The extent of this decrease was dependent only on the nature of the added amendment on AL soil. The adsorbed amounts of imazaquin on aged organic fertilized soils were usually fairly close to that on original soils. Results of soil column experiments indicate that addition of exogenous organic matter cannot be considered as a regular practice for retarded movement of imazaquin.

Quaternary herbicides retention by the amendment of acid soils with a bentonite-based waste from wineries

“…This strong retention to organically amended soil greatly limits any leaching or surface run-off of these herbicides [22]. In practice the application of organic amendments for retarded movement of the herbicides is more effective in sandy soils because of their originally lower adsorptive surfaces [51].…”

Sorption/desorption behaviour of sulfonylurea herbicides as affected by the addition of fresh and composted olive cake to soil

“…With respect to bensulfuron desorption, the H coefficient was lowest in soil amended with olive cake, indicating that desorption was inversely related to adsorption (Mamy & Barriuso, 2007). The composition and higher content of the OC from olive cake could be responsible for the greater retention of bensulfuron in soil amended with this olive residue (Undabeytia et al. , 2004).…”

“…An important management strategy for reducing herbicide leaching is to modify soil sorption potential by incorporating organic amendments, because a strong correlation has been usually observed between soil organic carbon (OC) content and pesticide sorption (Rouchaud et al. , 1997; Undabeytia et al. , 2004; Rodríguez‐Rubio et al.…”

Modification to Imazaquin Degradation in Soil Amended with Farm Manure

“…(Garcia and Takashima, 2003). So far, only one paper reported the effect of organic manure on imazaquin environmental behavior, which indicated that the two amendments affected sorption and leaching of imazaquin in soils (Undabeytia et al, 2004). However, no data are available on the effect of manure on imazaquin degradation in soils.…”