Data for The Effects of Sowing Time and Post-sowing Exotic Plant Management on Themeda triandra (kangaroo grass) establishment

The soil seed bank of degraded pastures is dominated by exotic plant species.<i> </i><i>Themeda</i> <i>triandra </i>Forrsk. (kangaroo grass) restoration studies have shown that post-sowing management of exotic plants is needed during seedling growth and establishment. In a paddock near Mylor, South Australia, we compared two spring sowing times (before and after summer exotic plant emergence), the removal of 50 mm of topsoil and five post-sowing treatments. These were hand weeding, applying sugar to the soil surface and three herbicide treatments to compare the growth and establishment of <i>Themeda triandra (hereafter Themeda)</i> over two growing seasons. The trial was irrigated to the equivalent of the annual average rainfall in the first summer.<br>Average use efficiency of viable seeds sown was 34 ± 4% after two years and gave a high percentage of <i>Themeda</i> cover for all treatments. Hand weeding resulted in the highest growth, with 2-3 times more midrow cover and over 10 times more culms than most other treatments in the first flowering. After two years, hand weeding also resulted in more than twice the <i>Themeda</i> biomass compared to the late sown control with <i>Themeda</i> making up more than 95% of the biomass. A single post-sowing herbicide application did not produce significantly higher biomass than the controls but also did not differ significantly from the hand weeded treatment, however the percentage of exotic plants was higher than for hand weeding. The high production in the hand weeded treatment, highlighted the substantial detrimental effects of exotic plants on <i>Themeda </i>establishment and biomass production. Nevertheless, our results are encouraging in showing that, in some circumstances, <i>Themeda </i>can establish swards with high percent cover with only pre-sowing weed control or a single post-sowing herbicide application. If the goal is to obtain a clean sward, maximise <i>Themeda</i> biomass and/or early seed production, more regular post-sowing exotic plant management in the first 12-18 months of establishment may be necessary.<br><br>