A review of grass species yields and growth rates in Northland, New Zealand

Abstract

Pastoral farming is a major land use in New Zealand's Northland region, with 3,171 farm holdings and a total area of 637,500 hectares in 2022. The region's pasture grasses include temperate (C3) and subtropical and tropical (C4) grasses which support dairy, and sheep and beef production from grazing. In lowland areas, C3 and some annual C4 grasses are prevalent where cultivation occurs, while perennial C4 grasses dominate areas with low soil fertility and summer dry conditions. Grass-based pasture growth rates (kg dry matter/ha/day) from published and unpublished sources were assembled into the AgYields database. Among the resident and sown grasses tested in Kaitaia, Kaikohe, Whangarei and Dargaville, perennial ryegrass represented ∼60% of the total data points. Dominant kikuyu pastures represented 23% and the remaining species represented 17%. Rates of growth ranged from 5 to 120 kg DM/ha/day, being lowest in late autumn-winter and highest in early summer. Data were compared and agronomic traits (i.e. drought tolerance, biomass production and tillering) are discussed to assess species suitability for the Northland environment. The medium-term prospect suggests an urgent need to improve research into management of cocksfoot and tall fescue-based pastures to provide viable alternatives to overcome the decreasing persistence of perennial ryegrass.