Earthworms - Soil Essentials: Managing Your Farm's Primary Asset - page 77

Table 18 Earthworm species found in farm soils

(Source: Soil Sense B-01)

Species Pasture Crop Burrowing habit

Aporrectodea rosea yes yes To 10 cm

Aporrectodea trapezoides yes yes To 20 cm

Aporrectodea caliginosa yes yes To 20 cm

Microscolex dubius yes yes Not very active

Microscolex phosphoreus yes yes Not very active

Lumbricus rubellus yes no Under dung pats

Note . All of these worms are found in lower rainfall (less than 600 mm/pa) pasture and cropping soils.

Why bother with earthworms?
Earthworms recycle plant nutrients in the soil thus making them available to
plants, and also improve soil structure and drainage. Their casts form stable
aggregates that improve the crumb structure of soil and they form channels in soil
that plant roots can follow and that assist soil aeration and drainage. Earthworms
incorporate plant litter into the soil and help release plant nutrients, aiding plant
growth. They are useful as biological indicators of soil health.

How to increase earthworm numbers
• Manage the soil to provide their food, water and physical requirements.

•

Add lime to acid soils, or soils deficient in calcium.

• Transport worms from areas that have good numbers. Remove small spades

full of turf from good areas and place the turf upside down on a 10 metre grid
on the area to be seeded when conditions are moist. It would help if the area
had recently been limed. The earthworms will fully colonise the new area in
six to seven years if conditions remain suitable.

How many earthworms is enough?
Worm numbers can be checked easily by digging about 20 shovels full of soil over
the area to be checked.
Crumble up the soil from each shovel full and count the worms, then divide by
the number of shovels full to get the average number. As a guide:
0-2 worms per shovel full poor

3-5 worms per shovel full good

>5 worms per shovel full great!

Source: Soil Sense B-01