The state of New Zealand soils

'I know that New Zealanders care about our land, and I am confident that together we can tackle the issues.'

Penny Nelson (MfE), while introducing the 'Our Land 2018' report

Declining soil quality

We are losing 192 million tonnes of soil a year. That’s the equivalent of four-hundred-thousand dump trucks of soil unloaded every week.

The idea that ‘what we cannot see cannot hurt us’ could not be more wrong in the context of New Zealand soils.

Soils provide several key services, most importantly growing our food, water drainage, storage and filtering, carbon and nutrient storage and recycling, and hosting a large part of our biodiversity. In New Zealand we rely heavily on soils for our economy, as soil provides the resources for primary production such as dairy, horticultural crops and wood. New Zealand landscapes that attract millions of tourists every year are also underpinned by soil.

It is therefore hugely important that we manage our soils well to sustain services and production from the soil. Soils develop over long time frames – millennia or longer – but can be lost very quickly through mismanagement and natural events.

FAO infographic: Our soils under threat

Pressures on NZ soils, and their drivers

New Zealand soils have some specific challenges, due to both the natural environment and historical management. The table below, adapted from the Our Land 2018 report by the Ministry for the Environment (MfE) and Statistics NZ, shows the most important pressures on our soils, the impacts, and where these pressures are an issue:

Soil pressure	Natural or human-influenced	Description	Potential impacts on soil	Where it is an issue
Earthquakes and landslides	Natural, although the rate of landslides is highly influenced by human land use, topography and geology.	Landslides triggered by rain and earthquakes are a leading contributor to erosion in New Zealand.	Increased erosion Loss of topsoil and reduction in productivity	Widespread – steep terrain is commonly prone to erosion in the form of landslides.
Intense rainfall events	Natural, but human-induced climate change is increasing the frequency of intense rainfall events.	Intense rain and wind contribute to erosion. While this is part of natural processes, rates of erosion are increased in extreme weather events, particularly in the absence of a complete vegetative cover.	Increased erosion Loss of topsoil and reduction in productivity	Widespread, but primarily in the Southern Alps and in North Island hill country formed on weak rock types. This is of particular concern in areas such as Northland and the east coast of the North Island.
Reduction in vegetation cover	Largely human-influenced, but some natural	Accelerated erosion can be caused by clearing native vegetation for farming or forestry, forestry harvesting, changing from forestry to pastoral farming, cultivation and harvesting of crops, and the effect of pests (e.g. rabbits) and plant diseases.	Increased erosion Loss of topsoil and reduction in productivity Loss of soil biodiversity Loss of soil nutrients (changed nutrient cycling)	Widespread, but hill country formed on weak rock types is particularly susceptible.
Agricultural intensification	Human-influenced	Increased production per area of land, often achieved through increased inputs (e.g. fertiliser, pesticides, water, and supplementary feed), and higher stocking rates	Increased erosion Degradation of soil and water quality Loss of soil biodiversity	Widespread, but especially true for intensive farming areas on flat to rolling land.
Urban expansion	Human-influenced	A switch from undeveloped or rural land to urban land use leads to the loss of soil for future use. This is of particular concern for high-class soil.	Decreased availability of high-class soil Loss of soil biodiversity	Auckland, Waikato, Tasman, Canterbury, Tauranga
Pollution and waste disposal	Human-influenced	A variety of industrial, commercial, domestic and agricultural activities can result in chemical and physical contamination of soil. Historical activities can leave legacy issues of soil contamination.	Degradation of soil quality and reduction in productivity Loss of soil biodiversity	Widespread but usually in hotspots (e.g. landfills, mining areas, and former sheep-dip facilities).

Based on the soil quality monitoring results of 11 regions in New Zealand, the state of our productive soils is within the target for most measured indicators. However, specific challenges for New Zealand soils are erosion, phosphorus levels (nutrient imbalances) and macroporosity (soil compaction).