The Ministry for the Environment and Statistics New Zealand reported in Our Land 2018 on the state of the soil and the state of indigenous biodiversity and ecosystems.
It showed significant changes in land use over the past two decades with a 10% expansion of urban areas at the expense of the most versatile land and a 7% contraction in agricultural land, which has become increasingly converted to dairy and used more intensively.
The report found NZ loses 192 million tonnes of soil each year, with 44% from pasture, and that 48% of tested areas falls short on soil quality in phosphorus content, which indicates soil fertility, and macroporosity, an indicator of the soil’s physical status.
Parker said he is “particularly troubled by how much of our urban growth is occurring in our irreplaceable, highly productive land” and has tasked officials to start work on a national policy statement for versatile land and high-class soils.
A national policy statement lets a government direct a local authority to amend a regional policy statement or district or regional plan to include specific objectives or policies.
“We have to ensure we have enough land to build the houses people need but we must protect our most productive areas too,” Parker said.
“This report must spark a greater effort to build our knowledge of land as it’s clear there are significant data gaps, which must be filled.”
The report shows more intensively used land is more prone to fall short on the quality standards with 51% of tested dairy sites reporting excess phosphorous and 65% below target for macroporosity.
“Healthy soil is like a sponge, full of holes that can absorb air and water,” Parker said.
“When it is compressed it can’t absorb water, which makes it more drought-prone and nutrients are more likely to run off into waterways.”
The report said a loss of tree cover accelerates soil erosion and the increased profitability of dairy contributed to deforestation and conversion. – BusinessDesk
