Soil Quality vs Soil Health

Date: 4 May 2020
Author: Hill Laboratories

Doran and Parkin (1994), defined soil quality as “the capacity of a soil to function, within ecosystem and land use boundaries, to sustain productivity, maintain environmental quality, and promote plant and animal health.”

The terms “Soil Health” and “Soil Quality” are generally interchangeable but quality tends to depend more on inherent soil characteristics such as soil texture and parent materials, whereas health has more of a dynamic nature i.e it is more about the ecosystem that the soil is supporting and how management practices can alter the soil over time.

The characteristics of healthy soil are as follows:

Good soil tilth – crumbly, well-structured, dark with organic matter (not compacted)
Sufficient depth – extent of soil profile for roots to find water and nutrients
Sufficient supply, but not excess of nutrients
Optimal pH
Low population of pathogens and insect pests
High and diverse population of beneficial organisms (including earthworms) – for organic matter decomposition and nutrient cycling, soil structure maintenance etc.
Low weed pressure
Free of harmful chemicals and toxins
Resistant to degradation (resilient)

Cropped soils or soils under other intensive growing systems can be at risk in terms of soil health, but regular soil testing is a useful tool to monitor changes over time and to help manage any degradation. Tests for soil pH, nutrients, soil nitrogen and carbon form a solid base of information to assess most aspects of soil health.

We have recently offered the new Hot Water Extractable Carbon (HWEC) test that is a very useful addition, as HWEC has been shown by NZ researchers to be highly correlated with soil microbial carbon and soil aggregate stability. We have kept this HWEC test very affordable ($20 per sample) to enable submission of more samples towards gaining a better understanding of typical values across different growing systems.

The occasional addition of heavy metals tests such as ‘Total’ Cadmium or ‘Total’ Copper, where there is potential for these to be elevated, will be useful information for auditing purposes and will allow for any practice-change that may be needed.

Visit the Client Resources page of our website for more information on agricultural and horticultural soil tests.