Lincoln and Massey plantain farmlet and grazing trials

At Lincoln, pastures containing an average of 17% Ecotain® plantain reduced annual nitrate leaching by an average of 33% and annual total nitrogen leaching by an average of 17% over four years, with no significant effect on milksolids production or profit.

At Massey, pastures with plantain reduced annual nitrogen leaching by 20-60% in the first two years. Results in later years were influenced by seasonal conditions, pasture composition and lower overall leaching risk.

Across both sites, the research shows plantain can significantly reduce nitrogen losses while maintaining milk production.

The Lincoln and Massey sites also hosted a range of experimental work covering nitrous oxide emissions, methane emissions, plantain pasture management, animal health and effects of plantain on animal urine, milk and blood. Publications from these studies are provided at the end.

Lincoln leaching results

Results showed that, over the four-year trial, the PL3 treatment, which contained an average of 17% plantain in sward dry matter, reduced annual nitrate leaching by an average of 33% compared with PL0 (ryegrass/white clover without plantain). Annual total nitrogen leaching was also reduced by an average of 17% (Table 1). There was no significant treatment by year effect, i.e. the differences between treatments persisted across the years.

Aside from nitrate, total nitrogen includes ammonium and organic nitrogen. Treatment differences in these latter nitrogen forms were small and not significant with an 8% reduction in ammonium N (P = 0.231) and 7% reduction in organic N (P = 0.144). Organic N leaching was 43 kg/ha/yr in the ryegrass/clover and 39 kg/ha/yr in the ryegrass/clover/plantain.

Lincoln plantain establishment and persistence

Pastures were established with Legion perennial ryegrass, Tribute white clover and Ecotain® plantain in March 2021. Over the four years, plantain content was maintained with over-sowing and under-sowing of Ecotain® plantain (Table 2).

Annual average and autumn plantain contents as a proportion of total dry matter are provided in Table 2. Autumn is the recommended timing for assessing plantain as this is the highest risk period for leaching. The data shows that plantain levels peaked in Autumn 2022 before declining and then stabilising at 12-13% in PL3 and 14-16% in PL6.

Lincoln milk and herbage production

Milksolids production was similar between treatments (Table 3). Imported silage was higher in the PL6 treatment in 2022/23, associated with lower spring pasture production in PL6 that year. Silage fed in other years was similar between treatments. Nitrogen fertiliser applied was the same across all treatments averaging 149 kg/ha/yr.

Herbage production was measured using multiple methods at the Lincoln site (Table 3). Results from using the rising plate metre with calibration cuts indicated larger treatment differences than using the standard winter equation, which does not account for the lower dry matter percentage of plantain. Using the winter equation, PL6 produced more than PL0 in the first year. With the calibrated equation, differences in the first year were not significant, but PL0 produced more than treatments with plantain in the following years. The back-calculated value from the Farmax model uses milk production and supplement to estimate herbage production. Herbage production was similar between treatments using this method.

At the Lincoln site, a new calibrated equation was developed for the rising plate metre, accounting for lower dry matter percentage of plantain.

Lincoln economics

An economic analysis using the Farmax model has been completed comparing PL0 to PL3 in Years 1-3 (Table 4). Actual Fonterra milk prices were used – NZD $7.92, $9.26, and $7.80 for Years 1 to 3 respectively (2021/22 – 2023/24). The analysis showed no significant treatment difference in revenue or profit over the three years.

Farm expenses were higher in the PL3 treatment, approximately equivalent to the costs of reseeding in each year (Table 2), which averaged $95/ha. Canterbury farmers partnering in the Plantain programme are maintaining plantain by spreading lower rates of plantain (2 kg/ha/year) with their annual maintenance fertiliser at a cost of around $46/ha.

An analysis of all treatments and years will be completed and published in due course.

Massey plantain establishment and persistence

The pasture treatments at Massey were sown in April 2019 and targeted 30% (Low, LPL), 50% (Medium, MPL) and 70% (High, HPL) plantain. Seed mixes and reseeding were applied as per Table 5. The High plantain treatment was resown in April 2021 to achieve the 70% target and was subsequently oversown with Italian ryegrass in March 2023 when clover levels became too high. The actual plantain percentage achieved in each treatment each year was generally lower than target.

Massey nitrogen leaching

Compared to a sward sown with perennial ryegrass/clover, average annual total N and nitrate leaching were significantly lower in the plantain treatments in the first two years of the Massey experiment (Table 6).

In Year 3, leaching was higher in the High PL treatment. This is likely due to the re-establishment of plantain and clover in Year 2 which resulted in very high clover (33%) and low ryegrass (13%), with 46% plantain. Higher leaching in that treatment resulted from the combination of pasture re-establishment (spraying, soil disturbance), high clover, and low ryegrass (and therefore lower winter activity) to utilise the extra nitrogen fixed from clover and mineralised from the soil. This was mitigated by oversowing with Italian ryegrass to utilise the extra nitrogen before Year 4. Leaching was numerically lower in the Low and Medium PL treatments than in the RGWC in Year 3, though treatment differences were not significant.

In Year 4, wet conditions meant low stocking densities through spring, and high amounts of silage made, to protect the paddocks from damage. The wet spring conditions were followed by a dry autumn and winter, resulting in low drainage. These conditions resulted in low leaching, masking any plantain treatment effect in Year 4. Year 5 was also characterised by low drainage, high pasture growth rates, lower than optimum stocking densities and high silage removal, also resulting in low leaching.

Massey production

There were no treatment differences in milk production. Pasture yield was similar between treatments except Year 4, which was characterised by wet winter/spring conditions and had higher pasture growth in the ryegrass/clover treatment compared to all plantain treatments.

Plantain Potency and Practice programme

The Lincoln and Massey trials are part of the Primary Sector Growth Fund Plantain Potency and Practice Programme, a seven-year collaborative research initiative led by DairyNZ and funded by the Ministry for Primary Industries, DairyNZ, PGG Wrightson Seeds and Fonterra. Research is delivered in partnership with Lincoln University, Massey University, Lincoln Agritech and the Bioeconomy Science Institute (BSI).

Visit the main programme page to learn more about the research and farmer guidance being developed to support plantain use on farm.