Oversowing arrowleaf clover on North Island East Coast dryland hill country – results from two farm case studies

Abstract

Low clover content of grass-based pastures is often a challenge on summer-dry hill country. This study measured the performance of oversowing arrowleaf clover (Trifolium versiculosum) on two East Coast properties  (Wairakaia in Gisborne and Tourere in Central Hawke’s Bay) following a herbicide/oversowing programme on steep uncultivatable hill country. Arrowleaf clover is a hard-seeded aerial flowering plant and the intention was for light grazing in Year 1 to achieve maximum seed set and develop a long-term seed bank to increase pasture clover content. In Year 1, dry matter production was 11.7 tonnes/ha at Wairakaia and 10.5 tonnes/ha at Tourere. Seed set was 425 and 1380 kg/ha, respectively. Because arrowleaf is hard seeded, little germination was expected in Year 2 and both paddocks were oversown in a cover crop of plantain (Plantago lanceolata) at Wairakaia and arrowleaf at Tourere. Over 3 years, the areas which had been oversown produced substantially more dry matter than adjacent resident pastures, with significantly higher herbage accumulation rates in the first two years. However, the high residual cover (‘trash’) that resulted from seed set was difficult to clean up. Moreover, subsequent germinations suffered from heavy slug infestations. Whilst oversowing with arrowleaf clover was successful in the first year, the challenges in managing arrowleaf clover in subsequent years means that arrowleaf clover is unlikely to have a role in improving clover content under a permanent pasture situation.