Responses of Lotus pedunculatus to sulphur fertiliser and defioliation regime in acid soils at low temperature

The potential for Lotus pedunculatus is greatest in acid soils on hill and high country, but requires establishment success, nutrient supply and grazing management. This work investigated the role of sulphur fertiliser and the influence of defoliation regime on production of Lotus in low pH, high aluminium soils. Yields measured in year one were positively related to soil sulphate but not phosphorus. Sulphur, applied at two sites (low or high productivity) at 0, 24 or 78 kg S/ha, failed to alter yield over three years. The site, at 1000 m a.s.l., had base vegetation of unimproved tussock, low soil pH and P (4.8 and 7 respectively) and high Al (30-40 ppm). Yields ranged between 1900 and 3200 kg DM/ha/annum and was reduced when initial plant numbers were lower. Lotus contributed 65- 85% of the herbage for grazing (excluding tussocks). Yields were maximised by defoliation to 2 cm height each season or once in autumn. Establishing high plant numbers increased productivity. Single, late season grazing promoted rhizome development and resulted in the highest yields by year 3. Grazing to 2 or 5 cm residual once a season produced similar herbage, but lower rhizome development.