Growth rates and persistence of annual and perennial clovers

This study quantified the temporal productivity of monocultures of four annual and two perennial clover species in a summer dry environment at Lincoln University, Canterbury, New Zealand. Clovers were ungrazed in the first year to enable natural re-establishment of the annuals, but grazed in the second year. In 2019 clover cultivar affected (P<0.001) yield in early spring (24th September) with ‘Viper’ balansa (Trifolium michelianum) producing 5.0 t DM/ha compared (P<0.05) with 3.5 t for ‘Arrotas’ arrowleaf (T. vesiculosum), 3.2 t for ‘Antas’ and ‘Woogenellup’ sub clovers (T. subterraneum), 1.6 t for ‘Kopu’ white clover (T. repens) and 1.2 t for ‘Relish’ red clover (T. pratense). ‘Arrotas’ grew 111 kg DM/ha/d from 14th to 28th August, ‘Viper’ grew 123 kg DM/ha/d from 28th August to 24th September and then 183 kg DM/d to 9th October. After a dry autumn in 2020, ‘Kopu’ white and ‘Relish’ red persisted, but only sub clovers ‘Napier’ and ‘Woogenellup’ successfully re-established. By 17th September, accumulated dry matter yield (t) differed with ‘Woogenellup’ sub (4.3) and ‘Relish’ red (3.7) producing more than ‘Kopu’ white  (2.8) and ‘Napier’ sub (2.2). ‘Woogenellup’ sub clover grew at 72 kg/ha/day from 20th August to 17th September, which was more than twice the rate of the other clovers (~30 kg/ha/day). These four clovers continued to provide grazable herbage through the second year. In 2020 the re-establishment of arrowleaf, balansa and Persian (T. resupinatum) clovers was poor, and each yielded <0.5 t/ha by 17th September, with their plots dominated by weeds. These results confirm monocultures of top flowering annual clovers are productive in their first year but poor re-establishment may occur in their second year. They may therefore be best suited as one-year specialised crops for grazing or conserved feed. The earlier growth profiles of the annual compared with perennial clovers suggests there is potential to increase their use in summer dry environments to meet early spring feed requirements of ewes and lambs.