Cities gobbling up most productive farmland

Unchecked expansion of towns and cities is gobbling up some of the country’s best farm land, a new report says.

The findings have prompted Environment Minister David Parker to investigate the unchecked growth of cities such as Auckland, and even the future of the traditional Kiwi lifestyle block, in order to protect productive land.

Our Land 2018 reports towns and cities grew 10 per cent between 1996 and 2012, with about two-fifths of new urban developments built on arable land. Parker held up the loss of prime market gardening land around Pukekohe to Auckland’s expansion, as an example.

‘‘I have asked officials to start work on a National Policy Statement for Versatile Land and High Class Soils,’’ he said.

‘‘We have to ensure we have enough land to build the houses people need, but we must protect our most productive areas too.’’

The report also found the state of biodiversity, native ecosystems, and soil continued to decline.

The country lost 31,000 hectares of tussock, 24,000ha of indigenous scrubland, and 16,000ha of forest between 1996 and 2012.

It was humble soil that created the most concern however, with ballooning intensive agriculture contributing to the estimated loss of 192 million tonnes of soil to erosion every year.

A little under half of this loss came from pasture.

The erosion created a double-whammy for climate change, with the sediment in river channels compounding flooding risks already posed by climate change.

Erosion reduced soil quality, impacting the health of pasture and crops, and also making New Zealand’s largest carbon sink less efficient at sucking up greenhouse gases.

Ministry for the Environment deputy secretary Penny Nelson said the report made it clear Kiwis needed to pay attention to what was going on with the soil, which underpinned the economy.

Land-based production from the likes of forestry, agriculture, and horticulture earned $35.4 billion in 2016 – half the country’s total export earnings. Tourism added an additional $14.7b.

‘‘This report also reinforces that our land-use decisions are putting our environment under pressure. What we do on our land has effects across our environment and economy. It affects our water quality, the marine environment and the volume of greenhouse gas emissions,’’ Nelson said.

Overall, roughly half of New Zealand’s land is now modified grasslands, cropland and urban areas.

While this leaves half as indigenous, these areas were mainly spread over hilly or mountainous terrain, and did not support large swathes of native flora and fauna.

Also causing concern were heightened phosphorus content in soil and higher rates of compaction of soil.

Nearly half of the 11 regions tested across the country were outside the target range for both these soil health indicators.

Heightened phosphorus levels could affect water health as the soil ran off, impacting native fish, and more compacted soil made it harder for plants and crops to thrive.

The area of land used for agriculture fell 7 per cent between 2002 and 2012.

In the same period land used for dairy grew by nearly half, and sheep and beef land use fell by a fifth.

The intensification of farming also steadily increa- sed, with rising numbers of animals by area.

All of it came at the expense of biodiversity and native ecosystems.

Of the 344 land animals classified as threatened, 83 per cent were still classed as threatened or at risk of extinction, and the status of 11 species declined. Progress was made for 20 birds, with 10 reliant on intensive conservation management.