Fate of the herbicide 14C-terbuthylazine in Brazilian soils under various climatic conditions

C-14-terbuthylazine was applied to three Brazilian soils in closed aerated laboratory microcosms, both under standardized and under natural Brazilian climate conditions. Volatilization from soil to air, leaching from soil to percolate water, and transport from upper to deeper soil layers were higher in sandy soil than in clay soil and in organic soil. Mineralization of C-14-terbuthylazine to (CO2)-C-14 was higher in sandy soil than in clay and organic soils under standardized climatic conditions, whereas it was higher in organic soil than in sandy soil under Brazilian summer conditions. Under natural Brazilian summer conditions, leaching as well as vertical transport within the soil were enhanced as compared to standardized climate conditions comprising lower precipitation rates; volatilization was strongly reduced under high irrigation conditions. (C) 2001 Elsevier Science Ltd. All rights reserved.