GRASSLAND IMPROVEMENT IN SUBTROPICAL GUANGDONG PROVINCE, CHINA .1. EVALUATION OF PASTURE LEGUMES

Tropical and temperate legumes were evaluated for subtropical grasslan ds (1522 mm annual rainfall) on high aluminium (A1 saturation >87%) Ha pludult soils at Lechang in north Guangdong Province, China. The evalu ations were of: (1) 82 accessions and cultivars in rows and mini-plots ; (2) 31 tropical and temperate legume cultivars sown in spring and au tumn on unlimed soil with low fertiliser inputs; and (3) the same legu mes compared when spring sown with Setaria sphacelata with and without lime. In Experiment 1, the best of the tropical legumes were: Chamaec rista rotundifolia (CPI 37234), Desmodium cuneatum (CPI 53953), D. het erocarpon (CPI 86277), Glycine sp. (P7874) and Stylosanthes guianensis (Q8442 and CPI 18750a), with the Ornithopus genus showing most potent ial of the temperature accessions. Wynn cassia was the most productive (> 1700 kg/ha DM) in Experiment 2 and is recommended for use as a ''p ioneer'' legume. The best temperate species were Maku lotus, Pitman se rradella and woolly pod vetch, all of which yielded > 1000 kg/ha DM. A ll Trifolium species showed symptoms indicating severe magnesium defic iency. Legumes responded differently to lime application: greenleaf de smodium, siratro, phasey bean and lotononis increased, stylos decrease d and cassia was unaffected. In Experiment 3, the temperature legumes failed to establish with setaria, but white clover production in pure stands increased by 2000 kg/ha DM with lime application. The implicati ons of these results with respect to further species selection, liming strategies and fertiliser policy (especially P, Mg and K) for grassla nd development in south China are discussed.