So, what can we rule out:
Ryegrass seed sowing rate
Trials comparing five sowing rates at three sites over five years, showed that different sowing rates had no effect on subsequent ryegrass survival.
New ryegrass cultivars
Sowing old cultivars (e.g. Nui) alongside new cultivars showed that new cultivars were no less persistent than old cultivars when it came to survival.
The fact that old pastures are persisting and productive; on many farms, whereas new pastures (sown to new cultivars) are often failing, could be an indicator that soil disturbance is a factor, since the soil has not been touched in the former, but will have been through some form of cultivation in the latter.
System type and stocking rate
Provided pastures are managed within current recommended guidelines for e.g. pre-and post-grazing pasture mass and removal of surplus feed as silage etc., there is no reason to believe that a system based on high rates of imported supplement and a high stocking will be any different in terms of persistence risk from a system based on low rates of imported supplements and a lower stocking rate. High input systems may have more levers available to prevent over-grazing (especially if they include a feed pad or stand-off area), however all the tools are there to also prevent over-grazing in a low input system.
Hauraki Persistence Project
DairyNZ wants to support farmers in the upper North Island affected by the poor persistence of perennial ryegrass-based pastures, so that they can consistently increase the amount of home-grown feed.
We have chosen to focus on a particular district (Hauraki-Matamata-Piako), given the severity of the issue in this area, the presence of motivated farmer focus groups (P3 Trust Hauraki Monitor Farms) and the existence of other projects related to environmental management.
The purpose of this project is to look at the climatic stress on pastures.