Potential and pitfalls of caucasian clover in southern New Zealand

Abstract

The potential of caucasian clover (Trifolium ambiguum M. Bieb.) to produce high quality forage and to establish in on-farm conditions was tested in southern New Zealand. Caucasian clover was established alone and after one year the plots were oversown with ryegrass, in November. After a further 6-month establishment period, dry matter (DM) yield and botanical composition were measured over the following two years. A 2 x 2 factorial design tested the effects of early or late flowering ryegrass and frequent (2 weeks in spring, 4 weeks in summer and autumn and twice during winter) or infrequent (4 weeks in spring, 6 weeks in summer and autumn, and once in winter) defoliation. Plots defoliated frequently produced less dry matter than infrequently defoliated plots (13260 and 16180 kg DM/ha respectively in year 1 and 9980 and 12250 kg DM/ha respectively in year 2, P<0.01) and had a lower percentage of caucasian clover (62 and 68% respectively in year 1, P<0.05; 50 and 56% respectively in year 2, P<0.05). Ryegrass flowering date had no effect on total, seasonal or compositional yields. On-farm experimentation investigated establishment methods, included direct drilling, pasture to pasture and following a brassica crop. Caucasian clover was sown alone at 4 kg/ha coated seed (Prillcote®) with 375 kg/ha drilling superphosphate (0-9-0-11) in November 2000. Four rates of nitrogen (0, 25, 50 and 100 kg/ha urea (46% N)) were applied in February, after emergence. Plant numbers were lowest in the direct drilled paddocks, intermediate in the pasture to pasture sowings and greatest following a brassica crop (3.5, 6.5 and 10.6 plants/m2 respectively, P<0.05). Rhizome length, taproot length and taproot weight were not significantly affected by either establishment method or nitrogen fertiliser. Competition from weeds, especially grasses, was the biggest single factor influencing plant number. Though caucasian clover has the potential to produce large amounts of high quality herbage, establishment problems restrict its' use. Keywords: defoliation, establishment, fertiliser, growth, methods, Trifolium ambiguum