@conference {4182,
	title = {BRIEF COMMUNICATION: Nitrate leaching under sheep and beef cattle grazing},
	booktitle = {Hamilton},
	volume = {85},
	year = {2025},
	pages = {16-19},
	address = {Hamilton},
	abstract = {<p>In recent years, there has been increased concern about the contamination of waterways with nutrients, in particular the nitrate-N (NO$_{3}$$^{-}$) leached from pastoral farms (Ministry for the Environment 2020). At higher concentrations (\&gt;11.3 mg N/L), nitrate-N can be hazardous to human health and aquatic life (Di \&amp; Cameron 2002). Nitrate-N leaching is known to be high under dairy cattle grazing, however, there has been little research to quantity nitrate-N leaching under sheep and cattle grazing, particularly in recent times. This study compared nitrate-N leaching under sheep and beef cattle grazing perennial ryegrass/white clover. It also investigated whether mixing Italian ryegrass with brassica can mitigate nitrate-N leaching relative to a brassica monoculture crop under sheep grazing. The measured rates of nitrate-N leaching were also compared with predicted values using Overseer. Twenty plots were sown in four treatments each with five replicates: sheep grazing perennial ryegrass/white clover, sheep grazing turnips/Italian ryegrass, sheep grazing kale, and rising one-year cattle (R1) grazing perennial ryegrass/white clover. Measured leaching losses under all treatments were small and there was no significant difference (P\&gt;0.05) in the nitrate-N leaching flux between treatments. The Overseer estimates of nitrate-N leaching were greater than the observed values. Further, Overseer modelling also predicts that there would not be differences in the leaching losses observed under sheep and R1 cattle grazing.</p>
},
	keywords = {Beef Cattle, Nitrate Leaching, sheep},
	author = {F.F.M. Algharibeh and L.M. Cranston and J.P. Millner and P.R. Kenyon and P.C.H. Morel and D.J. Horne}
}
