Regrowth performance of tropical forage legumes on infertile soils

Survival, herbage yield and nutrient use efficiency of ten tropical forage legumes were compared in pot trials using two soil types (red and yellow kandosols), widespread in Australia’s tropical rangelands, over a period of 22 months. Over this period, plants of Centrosema brasilianum cv. Oolloo, Desmodium virgatus, Macroptilium bracteatum (93.8%), Stylosanthes scabra, S. hamata (87.5%) and D. pubescens (68.8%) survived best. Arachis paraguariensis (37.5%), A. triseminalis, M. martii (25.0%) and C. pascuorum (18.8%) were less successful. The highest herbage yields were consistently produced by C. brasilianum, followed by M. bracteatum and the Stylosanthes cultivars. The annual species, C. pascuorum and M. martii gave high yields in the first 3 9-weekly harvests. The Stylosanthes cultivars produced most root nodules, followed by A. paraguariensis, C pascuorum, C. brasilianum and M. martii. D. pubescens, D. virgatus, M. martii, A. triseminalis and C. brasilianum had the highest nitrogen-use efficiencies, whilst C. brasilianum and the two Stylosanthes cultivars had the highest phosphorus-use efficiencies. All of the legumes increased the nitrogen content of the two soils significantly, especially S. hamata, A. paraguariensis, C. brasilianum, M. martii and M. bracteatum. Most of the legumes show promise for use in low-fertility tropical pastures, particularly C. brasilianum and M. bracteatum.