Post-sowing management
Reclamation sowings following mining generally aim to return the landscape to something similar to its original state. This implies the establishment of plant communities with appropriate botanical diversity. Post-sowing management is critical if this native plant diversity is to be achieved. In general terms, perennial native grasses are well adapted to stressful environments but not to frequent disturbance (particularly soil disturbance) or the addition of soil nutrients. Species that are adapted to high nutrient, disturbed environments have been classed as 'ruderals' and generally include annual grasses and broadleaf weeds. Therefore, post-sowing management must be designed to disadvantage such species and may involve the selective use of herbicides (where appropriate), slashing to reduce the competition for slower growing native grasses and fire when the fire response of the species in question is well understood. The use of large numbers of livestock for short periods of grazing can also advantage native grasses over competing weeds. The addition of fertilisers before or soon after sowing will nearly always advantage weeds over native perennial grasses.
Recent work at the St. Albans campus of the Victorian University of Technology, has indicated that T. triandra is extremely efficient in taking up mineral nutrients, particularly nitrate, and therefore effectively competing with C3 weeds. Mineralisation and the increase in available nutrients is stimulated by cultivation or by creating bare ground and the initial seedling density of T. triandra is therefore important in providing adequate competition to suppress weed seedlings during the establishment phase. Ground preparation prior to sowing must be aimed at minimising the amount of mineralisation, as must post-sowing management. Successful stands of T. triandra must be burned at least every five years or so to rejuvenate the plants, reduce nitrate levels, increase their ability to take up available nutrients and so provide effective competition to prevent the invasion of weeds.
