Herbicides are an essential component of crop production in Australia.
The increasing environmental demands on farmers, together with the need to reduce moisture loss through evaporation, have resulted in stubble retention systems being increasingly adopted on farms of the winter rainfall areas of southern Australia. In these areas, however, the dry summers frequently experienced in the south often do not allow for the leaching and breakdown of stubbles. Thus, at sowing time, leachate from the stubbles may interfere with the crop germination and establishment process. The leachate may contain allelochemicals and also herbicides stored in the stubbles from the previous year's application. There is, therefore, an important need to better understand the processes involved and the factors of influence so that management practices can be put in place to minimise its effects.