Reducing nitrogen leaching losses in grazed dairy systems using an Italian ryegrass‐plantain‐white clover forage mix

Abstract

In grazed agricultural systems, animal urine patches are the major source of nitrogen (N) leaching losses and can cause a decline in water quality. Urine‐N rates often exceed plant requirements, and there is a need for mitigation options to reduce the impact of agriculture on the environment. One approach is to use alternative forages to reduce urine‐N loading rates, or to increase N uptake. This study used lysimeters to determine the N leaching losses, dry matter yields and N uptake following ruminant urine application to an Italian ryegrass‐plantain‐white clover forage mix (IRPWC, Lolium multiflorum Lam.‐Plantago lanceolata L.‐Trifolium repens L.) or perennial ryegrass‐white clover (PRWC, Lolium perenne L.‐T. repens L.). Three urine treatments were applied: Control (no urine), Urine Actual (urine from cows grazing each of the forages: 508, and 664 kg N/ha, for IRPWC and PRWC, respectively) and Urine 700 (700 kg N/ha). Compared with PRWC (113 kg N/ha), N leaching losses were 88.9% lower from IRPWC‐Urine Actual (12.5 kg N/ha) and 45.5% lower from IRPWC‐Urine 700 (61.8 kg N/ha). These reductions were attributed partly to the IRPWC having higher cool season activity and ability to take up N during the cool period, and partly to the lower concentration of urine‐N, compared with PRWC. IRPWC is a promising alternative forage for future farm systems with the ability to reduce urine‐N excretion from grazing animals and cause large reductions in N leaching losses while producing the same herbage dry matter yields as PRWC.

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

“…However, the model version used also takes into account the effects of plantain on urinary N excretion by animals and the subsequent nitrogen load. Such an effect is estimated based on studies undertaken as part of the Forages For Reduced Nitrate Leaching Programme, which assessed the impact of various forages including plantain on nitrate leaching [ 10 , 14 , 18 , 19 , 30 , 31 ]. The full description and sensitivity analysis for implementation of plantain in Overseer ® was described by [ 32 ].…”

“…with greater growth at low temperatures) [ 13 , 14 ]. However, the benefits of these strategies in mitigating the environmental footprint of dairy systems were investigated in a short time frame and/or over a small physical scale, such as in lysimeter studies [ 18 ]. Whether the suggested mitigation strategies function over larger physical and temporal scales, or whether there are secondary effects on farm productivity and profitability, remains unclear.…”

“…Furthermore, secondary compounds in plantain alter N partitioning in the cow, resulting in more N in the milk and faeces and less in the urine [ 19 ]. Lysimeter studies have shown a reduction in nitrate leaching from cows grazing an Italian ryegrass, plantain, and white clover mix sward compared with leaching from a conventional RGWC sward [ 18 ]. This reduction in nitrate leaching was the result of lower urinary N concentration from cows grazing the plantain in addition to higher N uptake by the Italian ryegrass.…”

Editorial: Grass and Forage Science – 75 years of impact and service to the science of grasslands

“…Whilst a major emphasis of early papers was on the improvement and productivity of grasslands, there has been an increased emphasis on the ecosystem services that grasslands provide across the globe (D’Ottavio et al, 2018) and the ecological and societal pressures on grassland agriculture. Therefore, we have seen papers submitted that seek to understand nitrogen responses in terms of efficiency of plant responses (Sandaña et al, 2019) and the farming system implications of the role of nitrogen on forage quality and productivity, animal production and nitrogen leaching (O’Connor et al, 2019) including a revisitation of the role of legumes in this context (Guy et al, 2018; Niderkorn et al, 2019; Woods et al, 2018).…”

Effect of timing of cattle urine deposition and pasture composition on nitrogen leaching losses

“…Carlton et al (2018) found in a lysimeter study using Templeton sandy loam soil, 82% and 74% reductions in mineral N leaching from perennial ryegrass/white clover with plantain (PRG/WC/P), compared with traditional PRG/WC, when urine (700 kg N −1 ha −1 ) was applied in December and February, respectively. Woods et al (2018) found a pasture mix of Italian ryegrass, white clover and plantain (IRG/WC/P) leached 46% less mineral N than PRG/WC, when urine (700 kg N −1 ha −1 ) was applied in March, to a Templeton sandy loam soil. Welten et al (2019) found 15%, 27% and 52% reductions in mineral N leaching from pure plantain swards compared with pure PRG swards, for summer, autumn and winter applied urine (622 kg N −1 ha −1 ), respectively; this study was conducted on a Horotiu silt loam soil.…”