Natural reseeding of five grass species in summer dry hill country

Abstract

Natural reseeding of 5 grass species was monitored over 2-3 years in summer dry hill country in central Wairarapa and Taupo. Measurements included numbers of seedheads and seedlings appearing, survival andgrowth of tagged seedlings and their contribution to sward tiller populations. Effects of fertiliser (high, low) and summer grazing managements (continuously summer grazed, spelled from grazing during summer) were examined. All seedlings appeared in autumn/early winter. No seedlings of phalaris and few tall fescue and cocksfoot seedlings were found, and all failed to survive the first summer. Reseeding of prairie grass was significant, failure of which corresponded with a general decline in persistence of prairie grass swards. With summer spelling in central Wairarapa, prairie grass had relatively high seedling numbers (144/m?), seedling survival (10%) and contribution (11%) to prairie grass tillers in the sward. Reseeding was most prolific for perennial ryegrass (Nui and resident ryegrass) (283 seedlings appeared/m2). Summer spelling gave high ryegrass seedling numbers in central Wairarapa but lower numbers at Taupo, compared with summer grazing. At both sites, however, summer grazing increasedryegrass seedling survival and seedling contribution to the total sward (11% of total tillers), despite inherently dense, competitive swards. Effects of fertiliser were generally minor. Variation between sites and years was considerable. Reseeding had little effect on numbers of new plants in the sward, but may be significant when considered cumulativley over a number of years. Keywords natural reseeding, summer dry hill country, summer grazing managements, fertiliser, prairie grass, ryegrass, phalaris, cocksfoot, tall fescue