Soil Quality Monitoring

Soil quality defines whether soils are in good condition for their current land use activity. Because soils have developed from different parent materials and have been influenced by a range of soil-forming factors, soils display a variety of physical, chemical and biological characteristics.

What this means is some soil types will be better suited to certain land uses activities than others and the same soil type will need to be managed differently under different land use activities. Where soils are not managed appropriately, or where best practice still leads to degradation in soil properties, then we can say a soils quality is degraded and practices or land use may need to change. This page explains what soil quality is like around the Marlborough region and what we can do to look after our soil.

The Marlborough District Council began to monitor soil quality in the region in 2000. Between 2007 - 2022, 96 sites were sampled. Sites sampled represent a range of different land use activities including vineyards, cropping, pasture, dairy, native bush and exotic forest representing the major soil orders in the region. A recent review has noted that land use change since 2000 has altered the original range of soil orders and land uses sampled. As a result, the Soil Quality Monitoring Program will expand to 123 sites over the next 5 years.

Why do we Measure Soil Quality?

Widespread and increasing concern over the state of the environment and the impacts of human activities on ecosystem services and functions, highlights the essential need for high-quality, long-term datasets in order to detect environmental change and understand the effects of multiple pressures (Drewry, 2021) J.J. Drewry et al. Long-term monitoring of soil quality and trace elements to evaluate land use effects and temporal change in the Wellington region, New Zealand. Geoderma Regional (2021).

The collection of detailed soil monitoring data is vital because it provides information on what effect current land use activities are having on soil quality and whether we need to change or prioritise the way we manage the land environment. This is becoming increasingly important as land use activities such as dairying and viticulture are intensifying across New Zealand and putting pressure on our soils.

Measuring soil quality provides an early warning of the potential effects different primary land use activities may be having on long-term soil quality. It can help identify whether soil quality is degrading over time and what factors that may be contributing to soil degradation.

This information can then be used to help us to manage our soil resources in a sustainable manner in the future.

In addition, Regional (and Unitary) Councils have a responsibility for promoting the sustainable management of the natural and physical resources of their region. Under Section 35 of the Resource Management Act (1991), one of the physical resources that we have a duty to monitor and report on is soil. Specifically, to report on the “life supporting capacity of soil” and to determine whether current practices will meet the “foreseeable needs of future generations”. To help meet these goals, the Council undertakes a soil quality monitoring programme that involves collecting soil samples from a network of sites that represent the main land use activities and soil types within the region and analysing these samples for a suite of soil physical, biological and chemical properties that have been shown to be robust indicators of soil quality. Changes in soil quality take a long time to become evident. The Soil Quality Monitoring Programme has been operating since 2000 and has begun to clearly identify a declining trend in some soil quality parameters.

How do we measure soil quality?

There is no single measure for soil quality because there are many things about soil that affect its quality. From the array of possible measures, scientists have chosen nine key soil quality characteristics to measure in New Zealand soils. These have been grouped under biological, chemical and physical soil measurements.

These are:

Chemical	Biological	Physical
Soil pH Olsen P Trace elements	Anaerobically Mineralizable N Total carbon Total nitrogen Hot water carbon	Dry bulk density Macroporosity Aggregate stability

For further information on these soil quality characteristics and why they are important, our Annual Soil Quality Reports can be found on Council’s website.

For soil reports, go to the land publications and reports page

Maintaining Good Soil Quality

It makes sense to look after your soils - not only from an environmental point of view but also because healthy soils are central to plant growth and maintaining and enhancing agricultural and horticultural production. There are a number of things you can do to help maintain and enhance soil quality.

A series of Soil Quality recommendations can be found in Council’s Annual Soil Quality Report. A few of these are mentioned here:

For soil reports, go to the land publications and reports page