Weed community composition and rice husbandry practices in New South Wales, Australia.
Intensity of rice cropping was found to be a major environmental factor influencing the composition of the weed community during studies in the Murrumbidgee, Coleambally and Murray Valley irrigation areas of New South Wales. The four characteristic species Cyperus difformis, Elatine gratioloides, Damasonium minus and Echinochloa crus-galli, together with Diplachne fusca and Chara were positively correlated with intensive rice production. Two groups of plants were found to be associated with less intensive production. A group of semi-aquatic and terrestrial pasture species commonly occurred after direct drilling of rice and/or pasture rotation. The second group comprised native wetland species which were mainly associated with sites in which rice cropping was more recent and less intensive. The data suggested that the weed communities were not in equilibrium with the comparatively recent practice of rice farming in the region.