Effect of seed mix, sowing time, summer fallow, site location and aspect on the establishment of sown pasture species on uncultivable hill country

摘要

ABSTRACT This study aimed to determine which practices resulted in the greatest establishment (plant density) of a range of grasses, legumes and herbs at four geo-climatically different hill country sites in the North Island (three sites) and South Island (one site) of New Zealand. At each site, on a north and south aspect, a seed mix containing either grasses, legumes and herbs (GLH) or legumes only (LEG), was sown in spring 2011 and autumn 2012. The 2011–2012 summer rainfall was greater than the long-term average at all sites. Establishment of total sown species was greater in the GLH than LEG mix (14% vs 8% of germinable seed sown) although some species (white clover [ Trifolium repens ]) established more successfully when sown in the LEG mix. Establishment was greater from spring than autumn sowing at the two wetter sites, but greater from autumn than spring sowing at the two drier sites. Greater establishment occurred after a summer fallow or summer crop than after an autumn sowing for most species at most sites. Establishment of total sown species ranged from 5%–39%, depending on the site and treatment. Seedling establishment, as a percentage of germinable seed sown, was greatest for perennial ryegrass ( Lolium perenne ), white clover, red clover ( T. pratense ) and plantain ( Plantago lanceolata ) (up to 36%, 37%, 33% and 35%, respectively, averaged over sites), while cocksfoot ( Dactylis glomerata ), phalaris ( Phalaris aquatica ), grazing brome ( Bromus stamineus ), lotus ( Lotus uliginosus ), birdsfoot trefoil ( Lotus corniculatus ) and chicory ( Cichorium intybus ) were below 15%.