Productive land lost to urban growth
STUDY: Erosion and urban expansion are depriving the country of a vital resource — millions tonnes of soil
More productive soil is eroding away or being used for urban development, a new snapshot of land use has found.
The Ministry for the Environment and Stats NZ has just published the latest three-yearly update about the state of land around the country.
It shows that 5 per cent of the country’s soil was classified as highly erodible in 2022 — of that 60 per cent was in the North Island.
And despite soil being a finite resource, about 182 million tonnes eroded into our rivers in the same year.
“Our activities on land have compromised both the quality and quantity of our soils through deforestation, urban sprawl and intensification, and agricultural intensification,” the report said.
“Climate change is adding to these pressures, exacerbating flooding, landslides and erosion.”
It pointed out how vital soil was for New Zealand’s agricultural and horticultural economy which was worth $55.3 billion in the year to June 2023.
“For many Ma¯ori, soil is also of great cultural significance, fundamental to ma¯ra kai and viewed as a living entity with deep connections to whakapapa, ancestral lineage.”
The report said there was a 54 per cent increase in highly productive land being used for urban or residential purposes between 2022 and 2019.
The snapshot pointed out that reducing the land available for horticulture could have consequences for food prices.
“The reduced availability of highly productive land in the Auckland and Waikato District could contribute, alongside other factors, to an increase
Soil is crucially important because it is the foundation for other natural infrastructure.
— Natasha Lewis
in fruit and vegetable prices of up to 58 per cent across the country by 2043.”
Ministry for the Environment deputy secretary Natasha Lewis said ecosystems, such as soil, indigenous forests, wetlands, flood plains, and dunes were the foundation natural assets and infrastructure that underpinned our economy.
“Soil is crucially important because it is the foundation for other natural infrastructure. It also plays a vital role in our economy, soil is a strategic asset,” she said.
“A lot of our GDP is in the top 15cm of the ground we walk on.”
Lewis said the ways we use land were placing our natural infrastructure under pressure.
“Accounting for the full range of benefits that nature provides will help us to develop enduring solutions for the way we manage land,” Lewis said. ■