Our Land 2021, the latest in a series of reports produced by the Ministry for the Environment (MfE) and Stats NZ, focuses on land-use change and intensification.
The report says that only 15% of NZ’s total land area is particularly good for food production, whether that be farming animals or growing crops, and that between 2002 and 2019 the area of highly productive land that became unavailable for agriculture because it had a house on it increased by 54%.
Horticulture NZ chief executive Mike Chapman says that trend has to change, with urgent action needed to protect remaining areas of productive land.
“This situation simply isn’t good enough, considering that the primary production sector is the backbone of the New Zealand economy and only 15% of land is suitable for food production,” Chapman said.
“The Government must act now to retain remaining highly productive land. Once houses have been built on it, that soil is lost forever.”
Chapman says the Government launched its draft National Policy Statement on Highly Productive Land in August 2019, but no final decisions have been made on it since then.
“There has been no progress when clearly – as this Government report shows – there is an issue, which has the potential to compromise New Zealand’s ability to feed itself, fresh healthy food,” he said.
He says the new report is bold when it states that once land has been built on or is surrounded by houses it can be almost impossible to use for farming in the future.
“But you only have to drive south out of Auckland to see that this very thing is happening to the highly productive, unique soils around Pukekohe, just as it is happening across the country,” he said.
The report says the area of urban land in NZ increased by 15% from 1996 to 2018.
More than 80% (25,248 hectares) of the increase came from the conversion of exotic grassland to urban use, while 9% (2602 hectares) was converted from cropping or horticultural land.
The report says if current urbanisation trends continue, which include a doubling of residential land outside city boundaries from 2002-19, a large proportion of highly versatile land (land-use classes 1 and 2) could be developed into urban zones during the next 50–100 years.
It says to address the growing demand for housing there is a choice between building in existing residential areas (creating denser urban areas) or building outwards onto productive land.
Lincoln University professor Amanda Black says NZ is a crossroads of a business as usual approach to land management or a more informed and intergenerational approach.
“Fragmentation (subdivision of land into smaller pieces) and unimpeded urban sprawl that covers our best productive soils threatens to undermine our ability to feed ourselves and pay our bills,” Black said.
“Once land is in housing, it is gone for good. The loss of good productive soil is bad enough but the additional spillover impacts of creating urban areas means that we would be limited in how we manage weeds and pests, potentially creating weed and disease havens. We need to protect our best land and to do that we need strong policy.”
Manaaki Whenua Landcare Research research priority leader Dr Anne-Gaelle Ausseil says urban and rural residential expansion around cities like Auckland, Hamilton or Christchurch has disproportionately affected highly productive land and the ongoing and uncoordinated expansion on NZ’s best land might restrict future opportunities for the agricultural and horticultural sector, which also face a growing need to not only limit impacts on the environment but also to adapt to climate change.
In 2019, NZ’s land-based primary industries generated $44 billion in export revenue and the report noted that exports and domestic food production currently rely on a small amount of highly productive land.
“Using land that is not highly productive for food growing, especially horticulture, results in lower yields unless more intensive land management approaches are used,” the report said.
It says intensive land management is about getting the most from each hectare of land but it risks degrading the quality and health of the soil, particularly when using areas of land identified as less productive.
Food production is most efficient on highly productive land because its soil needs the least amount of fertiliser and cultivation (tilling or ploughing) to grow crops and livestock.
Highly productive land is also less prone to leaching fertiliser and contaminants into the environment than land with shallower or stony soil.
The report found that although no declining or improving trend in soil quality was observed between 1994 and 2018, at least 80% of monitoring sites nationwide failed to meet targets for at least one soil quality indicator.
