Conventional and reduced tillage as affecting herbicide leaching: experimental and simulation data

6 pages, 2 figures, 6 tables, 8 references.-- Se presentó un póster en el Symposium 20: Management of physical properties of tilled horizons, environmental and agricultural aspects.-- Congreso celebrado del 20-26 de agosto 1998, en Montpellier, Francia.

Conservation tillage increases water infliltration and requires higher herbicide rates which could lead to enhanced chemical transport to ground water. Recent studies on conventional and reduced or non-tillage systems as affecting pesticide leaching report contradictory results. Some studies report higher leaching for diverse herbicides from non-tillage (NT) than from conventional tillage (CT) systems due to preferential flow through macropores more abundant in NT than in CT (Isensee et al. 1990 and Gaston and Locke, 1996). Other studies report just the contrary and suggest enhanced sorption and degradation processes in NT could attenuate herbicide leaching (Levanon et al. 1993; Dao, 1995; Fermanich et al., 1996). The purpose of this study was to assess the influence of two tillage systems, conventional tillage (CT) and reduced tillage (RT), on the mobility of the herbicides clopyralid and metamitron in undisturbed soil columns, and to compare these results with those obtained in handpacked soil columns.

Finnancial support by CICYT Project AGR93-0613-CO2-01, PAI RMN 124 and Accion Integrada of MEC HB96-89 are acknowledged.

Peer reviewed