Liu, WendyPremaratne, ManjulaCresswell, Roger J.Dash, Daniel R.Jack, David . W.Andrews, Mitchell2018-04-272016Liu, W., Premaratne, M., Cresswell, R., Dash, D., Jack, D., & Andrews, M. (2016). Gorse is a ‘facultative’ N₂ fixer. Journal of New Zealand Grasslands, 78, 181-184. Available from https://www.grassland.org.nz/publications/nzgrassland_publication_2819.pdf2463-2872https://hdl.handle.net/10182/9269Many legumes reduce their atmospheric N₂ fixation per unit biomass in response to increased soil N availability but there are reports that some maintain a constant rate of N₂ fixation per unit biomass regardless of soil N levels. These different responses to soil N availability have been described, respectively, as ‘facultative’ and ‘obligate’ N₂ fixation strategies. Views in the literature differ if gorse is a facultative or obligate N₂ fixer. Here, firstly, the proportion of N derived from the atmosphere (%Ndfa) was assessed for mature gorse plants mainly in hedges bordering intensive agricultural land at different sites in the Selwyn district, Canterbury, New Zealand using the ¹⁵N natural abundance technique. Secondly, the effect of nitrate (NO₃⁻) supply on %Ndfa was determined for gorse seedlings under glasshouse conditions using ¹⁵NO₃⁻. Under field conditions, values ranged from 14.7-88.0 %Ndfa. In the glasshouse, %Ndfa values decreased from 97 when no N was supplied to 24 %Ndfa when N supply was increased to the equivalent of 200 kg N/ha. It is concluded that gorse shows a facultative N₂ fixation strategy.181-184enlegumenitrate¹⁵N natural abundancenitrate reductase activitygorseUlex europaeusJournal ArticleANZSRC::0503 Soil SciencesANZSRC::0701 Agriculture, Land and Farm ManagementANZSRC::050304 Soil Chemistry (excl. Carbon Sequestration Science)2463-2880https://creativecommons.org/licenses/by-nc-sa/4.0/Attribution-NonCommercial-ShareAlike 4.0 International