Management and productivity of white clover in a kikuyu grass sward in subtropical Australia

This plot-cut study, on heavy clay soil, evaluated the establishment, productivity and persistence of Haifa white clover (Trifolium repens) in a vigorous sward of kikuyu grass (Pennisetum clandestinum). Defoliation treatments were 5 or 12 cm stubble height in spring and 14 days or "when ready" (lower leaves beginning to senesce) in spring and autumn. Over the 2t/2 years of the study and under optimal defoliation treatment (5 cm stubble height in spring and at the "when ready" defoliation interval in spring and autumn), total yield of forage was 19 952 kg DMfha/yr, of which 57% was white clover. The reason for the loss of vigour of white clover in year 3 is not clear. It may have been due to the heavy infestation of the root knot nematode Meloidogyne or to defoliation management over the second summer, or both. Management at the transition phases between the two pastures (early autumn and late spring) is critical to success and is explained in the light of farmer experience. Keywords: defoliation management, Pennisetum clandestinum, subtropics, Trifolium repens