To evaluate if integrating vetch into a hay rotation can enhance biomass production and economic returns during the hay phase while maintaining the rotational benefits of vetch for the subsequent cereal crop.

• The soil analysis revealed no issues with acidification or salinity, indicating a suitable environment for vetch establishment. However, April's below-average rainfall and dry conditions may have impacted early plant development. Despite these challenges, oats exhibited the highest early-stage plant density, and biomass throughout the season, though with lower crude protein content. The lower nodulation activity of vetch indicates potential low nitrogen fixation for further rotations.
• Among vetch varieties, RM4 demonstrated the strongest early establishment, exceeding the species’ average plant density of 50–60 plants/m² (GRDC, 2017). It also achieved the highest biomass and crude protein levels. In contrast, Rasina had the highest weed concentrations, lowest establishment, and the lowest crude protein content. RM4’s better performance may be attributed to its adaptation to low rainfall, drought tolerance, and strong early establishment.
• Aphid infestations between August and September may have influenced plant growth and biomass accumulation in some vetch varieties. Despite this, vetch exhibited significantly higher protein content than both the mix and oats. These findings highlight the potential of vetch, particularly RM4, to enhance forage quality and biomass production in hay rotations. However, challenges such as weed pressure, nodulation performance, and pest susceptibility require further investigation to optimise economic returns and sustain the rotational benefits for subsequent cereal crops.