Predicitng yield of irrigated red clover (Trifolium pratense L.) pastures in response to temperature.

Two datasets from red clover monoculture pastures grown in Lincoln, New Zealand, were analysed to generate coefficients to predict red clover yield. The mean annual production of established red clover was 17.0±0.48 t DM/ha, with a maximum mean growth rate of 125±9.36 kg DM/ha/day (spring Year 2). In the establishment year irrigated red clover grew at a constant rate of 7.30±0.14 kg DM/ha/°Cd (Tb = 3 °C) throughout the year. In contrast, there was a splitline linear response in Years 2 and 3, which differed between years and decreased after the second week of January. Specifically, the growth rate in Phase 1 was 7.70±0.38 kg DM/ha/°Cd in Year 2, which was 16% higher than the 6.60±0.28 kg DM/ha/oCd in Year 3. The difference probably reflected increased competition from weed grasses as red clover content declined from >95% to ~75% of total annual yield. After January, red clover grew at 3.05±0.35 kg DM/ha/°Cd, in both years. This lower rate occurred in the mid-January-July period, and probably reflected a change in partitioning of assimilate to red clover roots in response to a decreasing photoperiod. The coefficients reported here for red clover need to be validated from other datasets. However, they provide easily transferable coefficients that can be used to estimate red clover yield under nonlimiting conditions for other locations. These could be integrated into feed budgeting software to assist onfarm decision making.