DairyNZ says its $5 million project examining why current pastures are yielding just two to three years of high performance before deteriorating should have some solutions that farmers can actually use, in another year.
David Chapman, who is based at Lincoln University, is leading a three-year examination of ryegrass and clover pastures and why they begin to fail long before the expected 10-12 years.
DairyNZ strategy and investment leader Bruce Thorrold says while drought and black beetle attack are obvious causes, there are many other possibilities.
He says it may be that the sown grasses, usually ryegrass, are dying out and being replaced by other species such as browntop or summer grass - or the ryegrass could be changing over time, with the more productive plants being displaced by less productive ones.
Another possibility is that the ryegrass is ageing, so that while still in the pasture it becomes a lower-yielding plant.
Mr Thorrold says the project is also considering farmers' claims that older pasture varieties stand up better than current ones. He says that could be to do with more stock using the pasture or the newer endophytes (helpful micro-organisms attached to pasture plants) being much less toxic to grazing animals.
He says the results of the study - which includes older pasture plants like Nui to provide a benchmark for comparison with newer plants - will feed into DairyNZ's forage value index.