Effects of aggregate size on the transport of two herbicides and a water tracer.

The effect of soil structure on the leaching of bromide and two herbicides is investigated using soil columns repacked with four aggregate size classe s (1-5, 5-13, 13-20 and > 20 mm) of a loamy and clay soil. The water and br omide exportations show small differences according to the aggregate size a nd the soil type. The transfer of the two herbicides is reduced in the fine st aggregates of the clay soil, whereas it is only slightly influenced by t he aggregate size in the loamy soil. (C) 2000 Academie des sciences/Edition s scientifiques et medicales Elsevier SAS.