The government's state of the environment report shows fertile land for food production is under threat as more lifestyle blocks are developed on the fringes of urban areas.
Environment Aotearoa 2019 is a report jointly produced by the Ministry for the Environment and Statistics New Zealand.
The growth of urban areas was threatening the supply of versatile land near Auckland and other regional centres, the report said.
Despite urban areas making up a tiny proportion of the country's total land area, at just 0.85 percent or 228,000 hectares in 2012, most New Zealanders live in these areas, 86 percent according to 2018 population estimates.
In urban centres, natural land cover is usually reduced to less than 2 percent, and most centres have been developed on the most fertile land.
Versatile land often has the best soils and has many agricultural uses, but between 1990 and 2008, 29 percent of new urban areas were on this type of land.
This means the land is gradually becoming unavailable for growing food, forcing growers onto more marginal, less productive land which requires more fertiliser.
A trend for lifestyle blocks has led to the fringes of urban areas being broken into smaller land parcels, and sold as blocks.
The number of lifestyle blocks has increased sharply in recent decades, with an average of 5800 new blocks a year since 1998.
A 2013 study found that 35 percent of Auckland's versatile land was used as lifestyle blocks.
This is being driven by population growth. Between 2008 and 2018 the population increased by 14.7 percent. Growth is expected to continue, with the highest rates in Tauranga, Auckland, and Hamilton, and lower rates in Wellington and Dunedin.