Pasture soil biological constraints - field bioassay

Summary

​A "bioassay" was employed to assess claims that adverse soil biology may constrain pasture production. The study indicated that loss of seedlings and root damage on subterranean clover during autumn-winter was substantial and widespread. Clear costs for pasture renovation were indicated even when good practices are employed. Moderate to severe root damage was recorded at all sites. This was associated with poor shoot vigour.
It is possible that sub-lethal damage to pasture roots constitutes a large, but underestimated cost to production because it was so widespread and because the damage occurs during autumn-winter when pasture yield limits stocking rate. DNA probes for root disease pathogens identified the pathogen profiles of paddocks and may be useful for indicating disease risks, guiding plant cultivar selection and appropriate use of pesticides. The probes enable novel insights into soil biology in farming systems.