Hard-seeded temperate annual legumes establish better in a tropical grass pasture when autumn-sown than spring-sown in a summer dominant rainfall zone, Australia

Temperate annual legumes can be effective companion species in tropical perennial grass pastures. These legumes are commonly sown in autumn following establishment of the grasses. However, it may be more effective to establish a seed bank before sowing the grass, or possibly sow the legumes as hard seed/pod in spring when the tropical grass pasture is sown. A study was conducted in northern New South Wales to compare establishment, regeneration and productivity of three hard-seeded legumes: bladder clover (Trifolium spumosum) cv. Bartolo, biserrula (Biserrula pelecinus) cv. Casbah and French serradella (Ornithopus sativus) cv. Margurita. The legumes were sown four times: either one or two autumns before digit grass (Digitaria eriantha) cv. Premier was established, the autumn following grass establishment or sown at the same time as the grass as either hard seed/pod segments or scarified seed (total of five treatments). While seasonal conditions influenced establishment success, autumn was the optimal time to sow temperate annual legumes to achieve a productive mixed pasture. The legumes can be sown 1-2 autumns before or in the autumn following grass establishment. Legume plant populations of spring sown hard seed/pod segments were lower than those autumn sown but they increased the following year.