THE ROLE OF ALLELOPATHY IN LEGUME DECLINE IN PASTURES .1. EFFECTS OF PASTURE AND CROP RESIDUES ON GERMINATION AND SURVIVAL OF SUBTERRANEAN CLOVER IN THE FIELD AND NURSERY

In a series of five trials, three conducted in the field and two in seed-flats in the nursery, it was shown that mulched residues from the perennial pasture grass Phalaris aquatica and from wheat (Triticum aestivum) reduced the germination and production of subterranean clover (Trifolium subterraneum). The deleterious effects observed with the mulched residues were not evident when the residues were incorporated into the upper soil layer. A reduction of the residues in pastures before the opening rains in autumn would appear to be an essential requirement to ensure good germination and early seedling vigour from the annual legume component in mixed legume/grass pastures, especially those based on P. aquatica.