Integrating Plantain (Plantago lanceolata L.) and Italian Ryegrass (Lolium multiflorum Lam.) into New Zealand Grazing Dairy System: The Effect on Farm Productivity, Profitability, and Nitrogen Losses

Abstract

A two-year farm system study was conducted at Canterbury, New Zealand to evaluate the effects on farm productivity, profitability, and nitrogen (N) losses of integrating plantain (Plantago lanceolate L.) and Italian ryegrass (Lolium multiflorum Lam.) into a ryegrass and white clover (RGWC)-based dairy system. Three farm systems were compared: (1) a lower input RGWC-based system (LIRG) with stocking rate of 3.5 cow/ha, annual N fertiliser rate of 150 kg/ha, and imported feed level of <1.2 t DM/cow/year; (2) a lower input ryegrass + plantain-based system (LIRG + PL) with a stocking rate of 3.5 cow/ha, annual N fertiliser rate of 150 kg/ha, and imported feed level of <1.2 t DM/cow/year; and (3) a higher input RGWC-based system (HIRG) with a stocking rate of 5.0 cow/ha, annual N fertiliser rate of 300 kg/ha, and imported feed level of >1.2 t DM/cow/year. Cows in the LIRG + PL system grazed a diverse mix of Italian ryegrass, perennial ryegrass, white clover, and plantain (60% of farmlet area), and a mixed sward of plantain–white clover (40% of farmlet area). The average annual herbage harvested was similar between LIRG + PL and LIRG (11.7 t DM/ha), but greater in HIRG (12.7 t DM/ha) with the increased N fertiliser rate. During the calving to dry-off period, the average imported supplement feed per ha was higher in HIRG (8.0 t DM) compared with LIRG (3.2 t DM) and LIRG + PL (3.7 t DM). Average milk solid production (MS; fat + protein) was similar in LIRG + PL (1640 kg/ha) and LIRG (1622 kg/ha), but greater in HIRG (2130 kg/ha). Estimated profitability (NZD/ha) at milk price of NZD 6.5/kg MS was 10% greater for HIRG than LIRG + PL and LIRG, and similar (<1.5% numerical difference) between LIRG + PL and LIRG. The average estimated annual N leaching loss from the LIRG and LIRG + PL was 31% and 56% less than the loss from the HIRG. These large reductions in N leaching loss were achieved without a large decrease in profitability (i.e., LIRG and LIRG + PL compared to HIRG). In addition, the estimated reduction in N losses from the LIRG + PL system compared to LIRG suggests that an Italian ryegrass + plantain-based dairy system is a viable strategy to reduce the environmental footprint while maintaining farm profitability. However, the environmental benefits of plantain and Italian ryegrass estimated in this study require further confirmation through direct measurements at full farm level.

Stacking nitrogen leaching mitigations in a Canterbury dairy system whilst minimising profitability losses.

“…The calculated reductions in N leaching for the single component mitigations reduced N leaching by 11% for N fertiliser reduction, and by 18% for plantain. This aligns with published work on the effects of reduced fertiliser-N and plantain mitigations (Harris et al, 1995, Al-Marashdeh et al, 2021. However, larger percentage N leaching reductions were expected for stand-off and nitrification inhibitor mitigations, although this is influenced by carry-over effects of saved N within the farm system and how effluent from the stand-off is managed.…”

“…#3) Including plantain (30% of annual DM yield) in the pasture sward to increase urine volume and urination frequency and reduce urinary N concentration. These combined effects reduce urinary N load in the urine patches and increase chances of pasture uptake of urine N (Al-Marashdeh et al, 2021, Mangwe et al, 2019. Plantain will be under-sown at 4 kg/ha, together with Italian ryegrass, every four years, costing $25/kg with an estimated cost of $100/ha to be added to $672/ha of Italian ryegrass under-sowing giving a total re-grassing cost of $772/ha per year.…”

Nitrogen Excretion by Dairy Cows Grazing Plantain (Plantago lanceolata) Based Pastures during the Lactating Season

“…In the last decade, plantain ( Plantago lanceolata )-based diets have been demonstrated to decrease urinary N concentration while not affecting milk production, relative to ryegrass-white clover pastures, in short-term studies [ 7 , 8 , 9 ]. A longer-term farm system experiment over 2 years showed milk production was unaffected by including plantain in the diet, and lower urinary N concentrations were predicted but were not measured [ 10 ].…”

Incorporating plantain into ryegrass-white clover mixed sward for an economically and environmentally sustainable dairy system: Year one of a farm system study

“…The farmlets were managed individually following decision rules and common management practices in the region as explained by Al-Marashdeh et al (2021). Nitrogen fertiliser (150 kg N/ha/y) was applied as urea in eight to nine applications to each paddock annually.…”

“…Farm system studies require a significant investment of resources and labour, and replication is often sacrificed in favour of long-term monitoring. For example, in a non-replicated farm trial comparing performance of dairy systems based on either Italian ryegrass + plantain or a conventional RGWC pasture, Al-Marashdeh et al (2021) reported similar farm productivity and profitibility but lower predicted N leaching and nitrous oxide emissions by implementing the Italian ryegrass and plantain into the conventional dairy system. To date, however, effects of plantain on farm productivity, profitability and environmental footprint have not yet been investigated in a replicated farm system trial.…”