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The annual quantities of nitrate-N (-N) and total N (TN) leached from mole and pipe drained dairy pastures on a Pallic soil, were reduced by an average of 52% and 42% (p < .05), respectively, by standing cows off pasture to ruminate and rest after grazing (Duration-controlled grazing, DC), compared to the standard grazing management (SG) of leaving cows at pasture between milkings. For the SG treatment, measured -N leached was 13, 8 and 21 kg N ha−1 and total N leached was 18, 13 and 26 kg N ha−1 in 2009, 2010 and 2011, respectively. Annual surface runoff contained <1 kg -N ha−1 y−1 and <3 kg TN ha−1 y−1. The deposition of urine in the autumn period had the greatest influence on the quantity of leached in winter drainage. DC grazing is a practical method to reduce N leaching from grazed dairy pastures. [ABSTRACT FROM AUTHOR]

Standing cows off pasture after 4 hours of grazing (duration-controlled (DC) grazing) was researched over 3 years (2008-2011) to compare the losses of nutrients in drainage and surface runoff water with losses under standard grazing (SG). Pasture growth rates, nutrient concentrations and apparent intake by cows were used to model nutrient removals from, and returns to, pasture. Pre- and post-grazing covers and apparent pasture intakes were similar for both treatments. Quantities of N, P and K returned to the DC plots in excreta and effluent were 34%, 0% and 45% less than those returned to SG plots. This reduction in nutrient returns was associated with a nil, 20% and 9% decrease in annual pasture growth on the DC plots in the three respective years. Reductions in annual pasture growth under DC grazing may be avoidable if nutrient removals are balanced with returns in effluent and fertiliser. [ABSTRACT FROM AUTHOR]

Sheep farmers can increase production levels as a means to improve economic outcomes. However, this intensification can potentially result in more nitrogen (N) leaching which is at odds with the increasing pressure on farmers to reduce the quantity of N lost into the environment. Therefore, there is increasing interest in the use of alternative forages, such as Italian ryegrass and plantain, which could potentially allow farmers to increase production while decreasing N leaching. This study quantified and compared the quantity of N leaching under sheep grazing four different forages: perennial ryegrass/white clover (RGWC), Italian ryegrass/WC (IRWC), plantain/WC (PWC) and a winter brassica. Five replicates of each forage were established on plots of 800 m2 (40 m x 20 m). Each plot had an independent mole-pipe drain system with tipping-bucket monitoring equipment at the end of the pipe drain. Drainage volume and N concentrations (nitrate-N: NO 3 ⁻-N; ammonium-N; total-N) in drainage water were measured to estimate N losses. The forages were grazed according to the best management practice for each forage type over a two-and-a-half-year period (Year 1: July-December 2019; Year 2: January-December 2020; and Year 3: January-December 2021). In the first two years of this study, NO 3 ⁻-N leaching losses under IRWC and PWC were very small (ranging from 0.4 to 0.5 kg N/ha), and they were not different (P > 0.05) from those under RGWC. However, in Year 3, the leaching losses under IRWC and PWC treatments were greater (P < 0.05) than those under RGWC. This increased leaching was probably due to the need to re-establish these pastures. As part of renewing these swards, the IRWC and PWC plots were fallow during the key late summer-autumn period. In contrast, NO 3 ⁻-N leaching losses under brassica forages (3.5–6.4 kg N/ha) were greater (P < 0.05) than under RGWC (0.5–1.5 kg N/ha). Overall, the leaching losses measured under sheep grazing the forages were much smaller than those commonly reported by dairy studies. [Display omitted] • In recent years, there has been significant concern regarding the leaching of nutrients from grazing systems. • This study quantified the amount of nitrogen leaching lost in drainage water from sheep grazing four different forages. • Mole-and-pipe drainage systems were used to monitor drainage volume and collect samples. • Overall, leaching losses under sheep grazing forages were small. • Modern sheep grazing systems may offer mitigation options for dairying areas with high NO 3 - leaching. [ABSTRACT FROM AUTHOR]

Simple Summary: Plantain (Plantago lanceolata) has emerged as a forage with the ability to reduce nitrogen (N) losses, in particular N leaching, from grazing dairy systems. For farmers to confidently incorporate plantain into their farms, research needs to demonstrate that these environmental benefits sustain similar production and farm profit than traditional ryegrass (Lolium perenne)–white clover (Trifolium repens, wc)-based pasture. The effect of changing the cows' diet to plantain-based pastures was evaluated over two lactation seasons in comparison to ryegrass–wc pastures. Cows grazing plantain-based pastures produced the same milk solids production, but a urine with a lower N concentration when compared to ryegrass–wc pastures. Plantain reduced the urinary N loads from individual urine patches via higher urine volume and reduced the total N loading onto pastures via a lower urinary N excretion to mitigate the N leaching losses from grazed pastures. Plantain pastures could be employed by farmers to reduce the nitrate leaching from dairy farms. The use of plantain pasture in dairy systems can potentially reduce nitrogen (N) leaching losses via the lower N concentration in the urine (UNc) of cows. Reducing the urinary N load while cows graze pastures can reduce the risk of N leaching losses from urine patches. Research needs to demonstrate that these environmental benefits are not at the expense of milk production and farm profit. Three groups of 20 cows grazed in the following three pasture treatments: (i) plantain, (ii) plantain–clover mix (plantain, red [Trifolium pratense] and white clover), or (iii) ryegrass-white clover (wc) pastures, from spring to autumn for two years. Each year, pasture intake, diet quality, milk production and animal N (milk and urine) excretion were evaluated in spring, summer, and autumn. The cows grazing the plantain and plantain–clover mix pastures produced similar milk solids as cows grazing ryegrass–wc pasture but reduced their UNc during summer and autumn, when compared to those grazing the plantain–clover mix and ryegrass–wc pastures. Plantain reduced urinary N loads onto pastures by a greater number of urine patches with lower urinary N loading rates. The results demonstrate that plantain pastures do not diminish milk solids production from cows, and the lower UNc from summer to autumn could reduce N being lost to the environment. [ABSTRACT FROM AUTHOR]