Interception and retention of atmospheric particles by stands of alfalfa and maize

Abstract

Stands of the gramineous (grass-like) type of plants such as maize and cereals, and cultured grassland display relatively high deposition capacities due to the typical morphology of their leaves, which gives rise to many efficient particle-trapping sites, i.e. sedimentation cavities in the leaf axils (angles between the leaves and stems), in which the pollutants accumulate and become stabilized. Leguminous plants such as alfalfa, which are used in fodder mixtures, have a dense leaf cover which intercepts a relatively large quantity of deposit (sedimentation cavities are limited in these stands). The retention time, however, is usually short, depending on the weather. From data on three harvests of alfalfa, we estimated the average quantity of polluting particulate deposit entering the food chain within the growing season as 11.18 kg ha −1, as against the 18.19 kg ha −1 found for maize.