• DairyNZ reports –

New results from DairyNZ’s Plantain Potency and Practice programme provide further evidence that incorporating plantain into dairy pastures can help reduce nitrogen losses to freshwater while maintaining milk production and farm profitability.

Final results from a four-year farmlet trial at Lincoln University Research Dairy Farm showed annual nitrate leaching was reduced by an average of 33 percent from 18 kg/ha/year to 12 kg/ha/year in perennial ryegrass–white clover pastures containing an average of 17 percent plantain dry matter, compared with pastures without plantain.

The Lincoln trial compared nitrogen leaching and production between farmlets with perennial ryegrass and white clover pastures sown with, or without, Ecotain® plantain.

The findings support those reported from the programme’s grazing trial at Massey University, several smaller component studies, and the aligned Low N Farmlet Trial, also at Lincoln University, that stacks plantain with other nitrogen mitigation options.

DairyNZ Senior Project Manager Kate Fransen says milk production remained consistent across both treatments. Herbage production and silage use were also similar between treatments.

“The findings demonstrate that plantain can deliver environmental benefits without compromising farm performance,” says Fransen.

Fransen says the nitrate leaching reductions achieved at Lincoln are more than double those predicted by current models which only account for the effect of plantain on reducing urinary nitrogen.

“The high water content of plantain dilutes the concentration of cow urine, and the nutritional makeup of plantain also causes more nitrogen to be diverted to faeces and milk, and less into urine”.

“We are now gaining a better understanding of the effects of plantain on drainage and nitrogen cycling in soil which result in additional reductions in nitrogen leaching.”

The programme aims to have these additional effects of plantain reflected in models such as Overseer by 2028.

One of the key findings was that relatively low levels of plantain still delivered good reductions in nitrogen losses.

“At the Lincoln site, we achieved consistent reductions in nitrate leaching over four years, despite plantain content plateauing to 10-15% in the final years of the trial,” says Fransen.

The programme has also worked with more than 30 partner farmers in N-sensitive catchments. This has provided practical insights on using plantain, and supported understanding of the wider farm systems implications and potential catchment-scale impacts through benchmarking and modelling.

Plantain is a short-lived perennial and mixed swards require ongoing maintenance through oversowing or undersowing.

Partner farmers have successfully maintained 10–15 percent plantain content by including Ecotain in new pasture mixes and broadcasting seed annually, at an estimated cost of $46/ha per year.

DairyNZ modelling indicates that achieving similar reductions in nitrogen leaching without plantain would likely require substantial reductions in nitrogen fertiliser use, imported feed and stocking rates, or significant infrastructure investment, with greater impacts on farm profitability.

The benefits of plantain for reducing nitrogen leaching are recognised in regulatory frameworks in Canterbury, Southland, Waikato, Bay of Plenty and Horizons.

Beyond reducing nitrogen leaching, research from New Zealand and Ireland indicates plantain may also help reduce methane and nitrous oxide emissions. Further work is underway to quantify these benefits.

“Farmers are looking for options that improve environmental outcomes while supporting productive and profitable farm businesses,” says Fransen. “The evidence continues to show that plantain can be an important part of that toolbox.”

Ecotain® plantain has been used in all programme trials where leaching has been measured and is proven to be effective at farm scale.

The Plantain Potency and Practice programme is a collaborative research initiative that commenced in 2021 led by DairyNZ and funded by the Ministry for Primary Industries through the Sustainable Food and Fibre Futures fund (now Primary Sector Growth Fund), DairyNZ, PGG Wrightson Seeds and Fonterra.

Research is delivered in partnership with Lincoln University, Massey University, Lincoln Agritech and the Bioeconomy Science Institute.

You can find more about the programme HERE.

Source: DairyNZ