Effects of sugar cane mechanical harvesting followed by no-tillage crop systems on leaching of triazine herbicides in Brazil.

摘要

Field (Sao Paulo, Brazil) and laboratory soil column leaching experiments were conducted to determine the movement of triazines where mechanical sugarcane harvesting was followed by no-till (NT) and conventional tillage (CT) groundnut production. The working solutions for the herbicides were prepared at 31.25, 62.50, 125.00 and 250.00 micro g/litre for simazine and 62.50, 125.00, 250.00 and 500.00 micro g/litre for atrazine and ametryn. Samples collected from different depths showed a high percentage of clay. No effect of depth on soil physical properties under NT or CT was observed. Organic carbon content was higher in the top layer for NT soils. There was an increase in moisture content and a decrease in organic carbon content with depth under both cultivation systems. Soil density was generally high under NT, mainly in the top layer. There was higher hydraulic conductivity for soils submitted to CT than NT, however, this did not reflect on the movement of the triazines. For both tillage systems, atrazine leached more than simazine..