Sutharsan RJeyakumar PBurkitt LMatse DTDhanuskodi RHanly JDonaghy DJCai H2025-10-022025-10-022025-09Sutharsan R, Jeyakumar P, Burkitt L, Matse DT, Dhanuskodi R, Hanly J, Donaghy DJ. (2025). Enhancing Biological Nitrogen Fixation Through Diverse Pasture Swards. Plants. 14. 17.https://mro.massey.ac.nz/handle/10179/73634Regenerative agricultural practices emphasize the use of diverse pasture species within sustainable agriculture production systems. The inclusion of a range of legume species in diverse pasture swards is likely to increase biological N fixation (BNF) across seasons, reducing the system’s reliance on synthetic N inputs. The present field study aims to quantify BNF in selected legume species within diverse pasture (combining 9 species) and standard pastures (ryegrass and clover combination) and assess their performance to identify the potential for improving N supply while maintaining year-round pasture quality. A year-round seasonal BNF was assessed by evaluating soil N status, nodulation patterns, plant composition, and conducting ¹⁵N natural abundance studies. The results revealed that the diverse pasture sward produced 5.4% more dry matter compared to the standard pasture, while soil mineral N (NO<inf>3</inf>⁻, NH<inf>4</inf>⁺) remained statistically similar between the two treatments. Nitrogen yield was 9.3% higher in the diverse pasture than in the standard pasture. ¹⁵N natural abundance analysis assessment revealed no substantial variation in BNF rates across treatments throughout the study. However, in contrast to standard pasture, the BNF rate in diverse pasture experienced a 3-fold increase from winter to summer, while the standard pasture exhibited a 1.5-fold increase. In both pasture systems, BNF increased with clover proportion up to 30%, indicating optimal fixation at moderate clover levels. The findings underscore the potential of diverse pastures when strategically managed to enhance seasonal BNF while sustaining pasture productivity.(c) 2025 The Author/sCC BY 4.0https://creativecommons.org/licenses/by/4.0/biological nitrogen fixation; diverse pasture; 15N natural abundance; nitrogen difference method; regenerative agriculturebiological nitrogen fixationdiverse pasture15N natural abundancenitrogen difference methodregenerative agricultureJournal article10.3390/plants141727272223-7747journal-articlehttps://orcid.org/0000-0002-9841-86452727