New Zealand’s largest privately owned testing laboratory, Hill Labs has introduced a new test to detect earthworm eDNA levels in soils, marking a significant development in soil health assessment. This test, developed in collaboration with AgResearch, is a New Zealand first and represents the beginning of an array of potential applications to provide real benefits across the agricultural sector.
Earthworms are often seen as indicators of healthy soil because they need good soil conditions to thrive. They also aid in aeration and nutrient mixing. In high-quality soil, a typical New Zealand paddock would usually have earthworm populations exceeding 400 per square metre and 250 per square metre in arable land.
Hill Labs’ earthworm eDNA test measures environmental DNA (eDNA) – tiny traces of genetic material left behind as earthworms move through the soil.
Existing methods to assess earthworm populations are labour-intensive and require specialist knowledge, limiting the number of samples and convenience. A typical field visual assessment involves digging down about 20cm with a spade, then taking a second slice about 35cm away to get a clear sample. The soil is broken apart with all worms picked out, counted and the species identified.
The new eDNA test, used in tandem with existing field visual assessments, offers a convenient way to enhance soil health monitoring.
Hill Labs founder and executive director, Dr. Roger Hill, who has played a large role in developing the test, shared his thoughts on its importance:
"Soil is the foundation of all life, essential for productive farming, healthy plants, and clean waterways. Our new earthworm eDNA test gives farmers an additional tool to better monitor soil health, helping to promote sustainable farming in New Zealand and beyond.
“The biological component of soil health is difficult to measure and measuring earthworms provides a high-level view of a soil’s biological health.
"And this successful earthworm eDNA soil test is just the beginning. We're dedicated to exploring the full potential of this technology across different crops and farming methods to support New Zealand's farmers and growers."
Hill Labs scientists, Lisa Hsu and Sara Loeffen, worked closely with AgResearch senior scientist and leading earthworm specialist, Dr. Nicole Schon, on this project, with the initial feasibility study funded by the Our Land and Water National Science Challenge via its Rural Professionals Fund.
Commenting on the benefits that the new test will bring, Nicole Schon said:
“Through research we are learning a lot more about soil health and the need to move beyond the limited set of measures and indicators that we used to rely on. This provides us with a richer understanding of what we can do to maintain or improve soil health for our primary industries.”
“We know that the abundance of earthworms and other biological activity is an important component for healthy soils, and having this new tool for testing the abundance of earthworms via eDNA is going to make measuring soil health easier and more efficient.”
Partnering with AgResearch, Hill Labs is gathering feedback from farm consultants and industry experts to refine and expand the test's applications. Future consultations will explore potential uses for this technology with tasks such as pest identification and pathogen detection. For instance, it could help farmers decide not to plant certain crops in areas prone to specific diseases like clubroot in brassicas.
Targeting the Predominant Earthworm Species
New Zealand soils have three main types of earthworms, each living at different depths and doing different jobs. Endogeic worms, like Aporrectodea caliginosa, are especially important. These worms create many burrows in the topsoil, feed on organic matter, and improve nutrient availability. They usually make up 70-80% of the total earthworm population in the soil, playing a key role in soil health.
The initial earthworm eDNA test offering from Hill Labs is for A. caliginosa only. Being the most common species, this is still very useful, and research is ongoing to develop a cost-effective way to routinely analyse for all three species of earthworm.
Leveraging their expertise in DNA testing from other areas of their business, Hill Labs developed the eDNA test for earthworms to provide farmers and producers with a convenient way to get an indication of the biological aspect of their soil health, and to open the door to a raft of many other potential applications in the near future.