Weeds seed bank changes for annual ryegrass ('Lolium rigidum' Gaudin) and other species under a range of farm management practices on the Liverpool Plains of northern New South Wales

The soil weed seed bank is recognised as the primary source of weed infestations on arable land. Knowledge of the weed seed bank dynamics for individual species would therefore be helpful in designing an integrated weed management program. Farm management practices will govern the size and composition of the weed seed bank. This paper reports two years data of a three year trial to characterise the seed banks of glyphosate resistant annual ryegrass ('Lolium rigidum' Gaudin) and other potentially resistant weeds in paddocks on farms on the Liverpool Plains in northern New South Wales where glyphosate resistant annual ryegrass occurred. Samples were taken from zero tilled and cultivated fields. Soil cores (10 cm depth and 2.5 cm diameter) were used to sample the fields. Soil samples were germinated under polyhouse conditions and the emerged weed seedlings were counted and identified. Knowledge of the cropping history and other chemical and cultural practices used by collaborator farmers are used to help to interpret the results. A total of seven weed species and a few unidentified broad leaf and grass weeds were found.