Pasture productivity in New Zealand 1990–2020: trends, expectations, and key factors

ABSTRACT Pasture productivity gains are critical for maintaining global competitiveness of New Zealand’s $38 billion p.a. animal product export industries. This review reveals that gains in pasture eaten on dairy farms declined sharply after ∼ 2001/02, from +1.48% yr −1 to +0.26% yr −1 despite continued increases in nitrogen (N) fertiliser use, stocking rate, irrigation, atmospheric carbon dioxide (CO 2 ) concentrations and products from plant breeding programmes. Thus, gains in pasture productivity (outputs relative to inputs) have also declined. Almost all of the increase in dairy pasture eaten since 1990 can be explained by increases in N fertiliser and stocking rate. Many farms may have reached the peak pasture yields possible within the climatic environment of the late twentieth century. Meanwhile, climate change in northern regions is placing downward pressure on pasture growth and persistence. Climate change also emerges as a key cause of declining production on sheep/beef farms in some regions, while elsewhere predicted increases in growth under climate warming and elevated CO 2 have not materialised. There is a major strategic knowledge gap regarding the state and resilience of the national pasture resource which potentially constrains the optimal allocation of scarce research resources to the key issues affecting future financial and environmental sustainability.