| Summary: | While mixed-species cover crops are gaining worldwide popularity, their utility in the ‘plough-out’ period in tropical sugar cane systems has not been investigated. Field trials investigating weed suppression (one season only), biomass production and nitrogen accumulation of single-species and mixed-species cover crops were conducted over two seasons on a commercial sugarcane farm in the Australian tropics. Mixed-species cover crops showed strong weed suppression, and were among the top treatments for biomass production each year, but did not yield the highest biomass in either season. Sunn hemp (<i>Crotalaria juncea</i> cv. Global sunn) produced the most biomass in the drier-than-average 2016–2017 season (>10 t dry matter ha<sup>−1</sup>), while soybean (<i>Glycine max</i> cv. Leichardt) produced the most biomass (5.3 t dry matter ha<sup>−1</sup>) in the wetter-than-average 2018–2019 season, highlighting the influence of seasonal conditions on species’ biomass production. The inclusion of multiple species in a short-term cover crop in the tropics where extreme weather events can occur can thus be seen as a risk mitigation strategy given the risk of failure of any given species in a given season.
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