DETAILS MATTER. It’s important to comply with proper protocols when using the mustard method for sampling earthworm populations, paying attention to the chemical mixing, area sampled and harvesting of the worms. This method should be repeated in a minimum of three areas to get the most accurate results, researchers say.

Put Some ‘Mustard’ on Your Earthworm Sampling Methods

No-tillers trying to get a better handle on earthworm populations might try a method used in France to find more individual species. But the trusty spade is quicker and cheaper for most.

(Editor’s Note: This article is being shared from an earlier edition of Direct Driller, a no-till magazine published in the U.K.)

The undisputed indicator of healthy soil is the presence of earthworms in the soil profile. There are various methods of sampling or extraction to estimate the level of worm communities and analyze the different species present.

But what method is best? Two extraction methods — one chemical and one mechanical — are commonly used in the field. The chemical approach involves pouring a mustard solution onto the soil while the mechanical method involves simply using a good spade.

Mustard contains an active ingredient, allyl isothiocyanate (AITC) which has urticating, or stinging, properties. As soon as worms feel the presence of the molecule they have only one desire — to flee.

According to protocols clearly defined by the Agricultural Observatory of Biodiversity, mechanical extraction consists of sampling — at several different locations representative of the land parcel — a block of soil corresponding to the dimensions of the spade used, then “delicately” dissecting the soil block to account for the current earthworm community.


Using The Mustard System for Earthworm Extraction

For optimal earthworm activity, choose a time when the air temperature is ‘normal’ and the soil is moist.

Materials required:

  • 12 pegs, string and tape to create three sampling areas of 10 square feet each
  • A 5-gallon watering can and watering hose
  • 60 ounces of Amora Fine and Strong mustard, divided into 10-ounce portions
  • 15 gallons of water and rinse…
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