Monthly Archives :

May 2019

Earthworm Engineers #4 – Manure & Earthworm Populations

1600 1067 Sectormentor for Soils

Welcome to the fourth and final post in our Earthworm Engineers series, where you can learn from some of the best science about the value of these amazing creatures. We’re so excited that Professor Jenni Dungait is now the editor of the European Journal of Soil Science – and she’s made some important earthworm papers open access for a month. We’ve picked our favourite four and summarised them in this blog series.

Access the earthworm archives in the European Journal of Soil Science, to learn more about the science behind on-farm worms!


#4: Quantifying dung carbon incorporation by earthworms in pasture soils

This study looks at the effect of different earthworm communities on the amount of soil carbon (within dung applications) shifted into the soil. They tracked this process by labelling the carbon with isotope tracing, which is a clever technique that gives a really specific picture of where exactly the carbon is moving to. The three main earthworm types were tested in different treatments: surface-dwelling worms (epigeic), deep-burrowing worms (anecic), and network-creating worms (endogeic).

First, the researchers found that with increasing inputs of dung, the abundance of earthworms tested also increased, presumably because the worms had a more consistent food source in these pots and could flourish!

Most of the tracked carbon was found in the soils top layer (0-75mm), although when the earthworm population included deep burrowing (anecic) earthworms, carbon from dung was often found at depths of up to 300mm, which shows just how effective these worms are at burrowing materials from the soil surface into its lower levels. The most successful treatments (with the greatest flow of dung shifted into soil organic carbon (SOC)) were those with all three types of earthworms present (epigeic, anecic and endogeic). So, a diverse population of worms is necessary for optimal dung break down into soils!

In pasture soils, dung left by livestock can therefore contribute to increased earthworm populations, as well as increasing soil organic carbon. This is important for the soils nutrient supply, and also helps to reduce CO2 levels in the atmosphere, which has potential to reduce the effects of climate change. In conventionally grazed systems, the quantity of dung deposited per hectare are less than the amounts used in this study, but it’s interesting to think about how this research adds to the evidence supporting mob-grazing systems, where livestock graze fields more intensively, and more manure is deposited per hectare as the stock moves through!


Earthworms are one of the best indicators of soil health – find out how to monitor earthworms on your farm.

Earthworm Engineers #3 – Organic vs Conventional Systems

5184 3456 Sectormentor for Soils

Welcome to the third instalment in our Earthworm Engineers series where you can learn from some of the best science about the value of these amazing creatures. We’re so excited that Professor Jenni Dungait is now the editor of the European Journal of Soil Science – and she’s made some important earthworm papers open access for a month. We’ve picked our favourite four and summarised them in this blog series.

Access the earthworm archives in the European Journal of Soil Science, to learn more about the science behind on-farm worms!


#3: The impact of soil carbon management on soil macropore structure: a comparison of two apple orchard systems in New Zealand

This study compares two sites of the same soil type under apple orchards on one farm. One site had been under organic treatment, with regular compost application and grass cover, while the other was under ‘conventional’ treatment, with regular irrigation, fertilisation and herbicide applications.

When testing for earthworm populations, the researchers consistently found more earthworms in the organic soil compared with the conventional soil. They also reconstructed the 3D ‘macroporosity’ structure of both soils using X-rays, and again found greater macroporosity within the organic soil compared to the conventional soil. This isn’t a coincidence! Macroporosity is defined as the network of pores with a diameter of over 0.3 mm in the soil, and earthworms are known to create these kinds of channels.

This increased macroporosity is important for several reasons. First, it is known to increase the rate that CO2 in the atmosphere is locked up as soil organic carbon (SOC), which both increases soil fertility and also has potential to reduce the rate of climate change. As expected, this study then found that the organic orchard had a 32% greater SOC content than the conventional soils! Increased macroporosity also improves the soil structure, as the stability of soil aggregates is increased, which allows more microbes to live in the soil.  

Denitrification rates are known to increase in anoxic, water-logged soils, which leads to increased emissions of N20, a gas that contributes to climate change. As a result, increased macroporosity reduces denitrification in the soil, by allowing oxygen to penetrate into the topsoil, and reducing the chances of water logging.

It’s amazing to see evidence of how organic techniques allow our earthworm friends to flourish, and how positive their presence is in orchard soils!

Read the fourth and final instalment of our Earthworm Engineers series here!


Earthworms are one of the best indicators of soil health – find out how to monitor earthworms on your farm.

Earthworm Engineers #2 – Arable Farming & Earthworm Populations

5184 3456 Sectormentor for Soils

Welcome to the second in our Earthworm Engineers series where you can learn from some of the best science about the value of these amazing creatures. We’re so excited that Professor Jenni Dungait is now the editor of the European Journal of Soil Science – and she’s made some important earthworm papers open access for a short time. We’ve picked our favourite four and summarised them in this blog series.

Access the earthworm archives in the European Journal of Soil Science, to learn more about the science behind on-farm worms!


#2: Effects of different methods of cultivation and direct drilling, and disposal of straw residues, on populations of earthworms

This paper was written in 1979, and uses some pretty intense soil sampling methods (dousing the sample sites with formaldehyde to isolate worms) – we think they probably could have done with Sectormentor for Soils to count earthworm populations at each site!

The paper makes some interesting conclusions about the effects of cultivation on earthworms in topsoil. They tested the number of earthworms over four years on direct-drilled fields that were sprayed with herbicide before planting, and ploughed fields (of varying soil types). They found earthworm populations were consistently greater in the direct-drilled soils compared with ploughed soils, although deep-burrowing species were affected similarly in both treatments.

They also test the effect of spreading mulch on the fields compared to burning straw residue, and find (unsurprisingly) that earthworm populations were greater in fields where straw residue was spread rather than burned, particularly in surface feeding species. This surface debris becomes an important food source for the worms, and makes their diet more stable.

The paper also suggests that the extra earthworm channels created under no-till soils may help to reduce any compaction in the soil, as well as distributing organic matter and increasing drainage. The presence of worm channels may also allow plant roots to penetrate more deeply, which can also reduce compaction.

It’s nice to know that regenerative farming approaches have such a positive influence on the earthworm community. We’re really excited to speak at Groundswell this year on how to become a soil expert on your farm, and to learn more about the benefits of no-till systems.

Ready for to learn even more about the wonder of worms? Read part 3 of Earthworm Engineers here.


Earthworms are one of the best indicators of soil health – find out how to monitor earthworms on your farm.