Summer fallow weeds: a national study - water, nitrogen, seed banks and impact on subsequent winter crops

Abstract

An experiment to determine water and nitrogen use by summer fallow weeds and the impact these have on subsequent wheat crops, has been implemented in 3 cropping areas (Queensland, New South Wales and Western Australia) of Australia. While extensive data have been collected during the first fallow and cropping phases, it is too premature to draw conclusions. Seasons have been different and responses have been variable across the trial sites. Some similar trends have been noted in response for some variables at 2 but not all 3 sites. Weeds on wet fallows reduced yields in following wheat crops in Queensland and West Australia, but not in New South Wales. In both Queensland and Western Australian trials, soil nitrogen was significantly reduced where weeds were left to flourish under wet conditions.