Spring and autumn establishment of Caucasian and white clovers with different sowing rates of perennial ryegrass

The effect of sowing date (SD) and sowing rate of perennial ryegrass (PRG) on the establishment of Caucasian and white clovers in New Zealand was assessed. Clovers were sown in spring on 24 September (SD1) and 9 November (SD2) 1999, and in autumn on 4 February (SD3) and 31 March (SD4) 2000. On each date, clovers were sown with 0, 3, 6 or 12 kg ha^?1 of PRG. Total herbage dry matter (DM) production up to 6 November 2000 was 13–16 t DM ha^?1 for SD1 and SD2 when sown with 3–12 kg ha^?1 of PRG, and 7–10 t DM ha^?1 for sown clover monocultures. For SD3 and SD4, total herbage production was 6–9 t DM ha^?1 with PRG, while total herbage production of clover monocultures was 5·4 t DM ha^?1 for SD3 and 2·6 t DM ha^?1 for SD4. By 6 November 2000, white clover contributed proportionately more than 0·15 of herbage mass when sown with 3–12 kg ha^?1 of PRG on SD1, SD2 or SD3, but less than 0·09 when sown on SD4. The proportion of Caucasian clover never exceeded 0·09 of herbage mass in any of the swards. White clover was successfully established in spring and in autumn with 3–12 kg ha^?1 of PRG provided the 15‐mm soil temperature was above 14 °C. None of the combinations of Caucasian clover and PRG provided an adequate proportion of legumes during the establishment year. This unsuccessful establishment of Caucasian clover with PRG was attributed to its inability to compete for available light as a seedling due to slow leaf area expansion from secondary shoot development and a high root:shoot ratio. Alternative establishment strategies for Caucasian clover may include the use of slow establishing grasses, cover crops and temporal species separation.