Survival of 13 Forage Legumes in Contrasting Environments of Central Otago, New Zealand

Abstract

The lack of suitable perennial and annual forage legumes strongly constrains the productivity and sustainability of upland grasslands in New Zealand. Legumes support sustainable grassland production through nitrogen fixation and increased yields. However, traditional legume species such as white clover (Trifolium repens L.) struggle to persist within New Zealand's upland climatic and edaphic conditions characterised by acid, low fertility soils and short growing seasons. To address this challenge, we assessed the survival of 13 forage legume species over 2 years at three field sites across Central Otago, capturing the districts varied precipitation and temperature profiles. Legume survival rates, biomass and weather data were measured. Notably, lotus (Lotus pedunculatus Cav.) exhibited 100% survival over the 2 years on high altitude acidic, low fertility soils, whereas other perennial legume species showed limited persistence (0%–55% survival) and low biomass production. Crimson clover (Trifolium incarnatum L.) had the greatest Year 1 establishment and biomass of annual legumes species at low and medium rainfall sites. Moreover, strong Year 1 seed set and subsequent regeneration in Year 2 were observed for crimson clover, striated clover (Trifolium striatum L.), and subterranean clover (Trifolium subterraneum L.) (cvs. Denmark and Narrikup). These findings underscore the potential of these annual legume species in dryland environments due to their regeneration capacity before summer drought onset. Climate emerged as a pivotal determinant influencing the viability of less resilient species across all trial locations. Lotus and crimson clover are alternative legume species with the potential to enhance sustainable grassland productivity in New Zealand's upland farming systems.