ASPECTS OF THE ROLE OF CATTLE SLURRY IN DISPERSAL AND SEEDLING ESTABLISHMENT OF RUMEX OBTUSIFOLIUS SEED IN GRASSLAND

Two experiments were carried out to examine the association between ca ttle slurry application and abundant Rumex obtusifolius populations in grassland, In Experiment 1, the viability of R. obtusifolius seed, co llected between June and November 1993 was assessed after being subjec ted to (i) 100 days in silage (pH 4), (ii) 72 h rumen fermentation and (iii) 100 days in cattle slurry, In Experiment 2, the emergence of R. obtusifolius seedlings in gaps (5 cm(2) to 30 cm(2)) in a pasture swa rd, created either in autumn or in spring by (i) applications of cattl e slurry, (ii) physical destruction of the sward canopy or (iii) appli cations of artificial urine solution, was examined, Seeds collected in early June failed to germinate while those collected in late June had a 10% rate of germination and this increased to 85% for seed collecte d in early August, with no further increase with later harvests (mean 67.2%). Seeds were non-viable following ensiling, while those stored i n cattle slurry were not significantly (P < 0.05) affected (mean 64.9% ) and those which were subjected to rumen fermentation showed a signif icant (P < 0.05) reduction in the viability (mean 24.9%), In Experimen t 2, autumn applied cattle slurry favoured the establishment of R. obt usifolius seedlings (1 to 2 seedlings per gap) in grassland. The assoc iation between cattle slurry and R. obtusifolius populations in grassl and is probably due more to favoured establishment of seedlings follow ing application of slurry rather than dispersal of seed within the slu rry.