Plantain leading the fight

Now is not the time to stop incorporating plantain into dairy pasture systems to reduce nitrogen loss, says Agricom Australasia brand manager Mark Brown.

Regardless of doubts raised last winter by a group which challenged the interpretation of some of the science supporting plantain’s nitrate-busting ability, Brown says farmers can confidently include the herb in their pasture systems and know it reduces nitrogen losses.

“We’ve never suggested plantain is the only pasture species that could help in the fight to reduce nitrate leaching in our pasture systems,” he says.

“But there’s 15 years of science and development behind Ecotain® (plantain), OverseerFM recognises its ability to reduce nitrogen losses and several regional councils do too.”

“For many dairy farmers, maintaining a good percentage of plantain in their farm’s pasture sward is one of the only ways they can fend off the pressure to reduce stocking rate to meet their catchment’s nitrogen limit.”

Questions raised about plantain’s effectiveness by the group of scientists and rival seed company technical staff last July created confusion among dairy farmers, he says.

Many had already begun including plantain in their pastures, but some put their plans on hold because of the uncertainty which developed.

Brown hopes farmers know about two counter-responses which were published in the New Zealand Journal of Agricultural Research a month after the initial paper was published.

One was from scientists working on the Sustainable Food and Fibre Futures Plantain Potency and Practice programme and the other was from a group of scientists from AgResearch.

Both responding groups stood by their earlier trial work which demonstrates plantain (Ecotain environmental plantain) is an effective mitigator of nitrogen loss from pasture systems.

Brown says a mid-term review of the SFFF project, published last September, also concluded plantain reduces nitrate leaching and can help improve freshwater quality.

New research published in Ireland supports plantain’s positive impact on nitrogen leaching and results closely align with those from the earlier NZ trials.

The Irish trials investigated nitrate leaching over two years across different soil types from ryegrass-white clover swards with 0, 30 and 50 per cent Ecotain plantain.

On free-draining soils, nitrate losses from swards with 30 per cent Ecotain were 56 per cent lower in year one and 96 per cent lower in the second year, compared with the plots with nil Ecotain.

Losses from swards with 50 per cent Ecotain were 78 per cent lower in year one and 98 per cent lower in year two.

Morrinsville dairy farmer Johan van Ras, who is a partner in the SFFF project, says farmers still only have limited options for reducing nitrogen losses from pasture systems.

“There is no single silver bullet for dealing with nitrogen losses. It is going to take a range of tools in the tool box to achieve the reductions needed,” he says.

“At this stage, plantain is really the only tangible tool we have, so it was a no-brainer for us to take a closer look and see how it can be incorporated into our farm system.”

He has been testing different methods to establishing and maintaining plantain in the pasture sward, including over-sowing (prill-coated) seed with serpentine superphosphate.

His confidence in plantain is helped by its recognition within OverseerFM.

“We aim to maintain plantain at about 10 per cent of the total sward. At that level in Overseer, it provides a reduction of about two kg per ha of nitrogen loss in our system,” he says.

That reduces the farm’s average loss from the mid-20s to the low-20s which helps keep it at the lower end of the scale for nitrate leaching.

van Ras says commentary raised last spring by a small group of scientists who questioned the earlier science about plantain’s ability to mitigate nitrogen leaching from pasture systems created some confusion among his farming peers.

“We have to trust the science and test the tools it provides in a practical sense in our own farm systems.

“I’m not saying we should not have the debate and challenge any new practices developed by scientists. But as farmers, we also need clarity and certainty so we can adapt our systems with confidence,” he says.