Using plantain (Plantago lanceolata) with other on-farm strategies to meet N loss reduction targets while maintaining profit in Rotorua Lake catchment

Abstract

make significant reductions in nitrogen (N) leaching to improve freshwater quality. One option is the inclusion of plantain (Plantago lanceolata L.) in pastures, which has been shown to reduce N leaching without compromising pasture or milk production. From 2022-2025, we worked with five Rotorua partner dairy farmers to develop strategies to establish and maintain plantain in pastures as part of a whole-farm approach to reducing
N loss to water while limiting impacts on profitability. Modelling and benchmarking were used to determine the impact on N leaching and profitability at farm and catchment scale. Farms on well-drained pumice or podzol soils achieved up to 20% plantain (%DM) by broadcasting 4-6 kg/ha of coated plantain seed (2-3 kg/ha bare seed) across the whole farm each year, costing $45-$68/ha per year. Plantain content in pasture
DM varied from 1-65% depending on establishment method, management, soil type and contour. Including 20% plantain in pastures was estimated to lower N leaching by 8-14% with a 1-2% reduction in profit. Using plantain in a modelled mitigation stack to meet the 2032 N loss reduction targets (27-30% reduction from 2021-22 N loss), resulted in 4.7-7.5% higher profit/ha/year compared to meeting the same targets without plantain. At catchment scale, implementing plantain at 20% DM content of pasture was estimated to reduce N entering Lake Rotorua by 39 t N/year. A case study using benchmarking data demonstrated high profitability with low N loss by maintaining a lowcost structure, strategic use of mitigations including plantain, and tactical management of low N fertiliser inputs.