While farmers may be used to taking headcounts for stock, they're now being asked to check the number of earth worms in their ground.
The Waikato Regional Council wants farmers to count the number of worms in a 20cm cube of soil, with 30 to 35 worms being the ideal number.
Worms increase the depth of topsoil and the carbon content by burrowing, digesting and mixing soil and plant residues.
They also reduced surface run off of contaminants from grass into waterways, the council said.
To increase worm populations, the council said farmers should check calcium levels, limit use of fumigants and pesticides and reduce ammonium-based fertilisers, as they made soil acidic.