Children from Waihi schools participated in an earthworm study in association with Martha Mine recently.

A total of 301 Year 5 and 6 students from the six local primary schools were involved in the project, which culminated in a worm seeding exercise for each school at Waihi Gold Mining Company’s waste rock embankment.

Waihi Gold’s Education Officer prepared a unit of lessons for teachers of Year 5 and 6 classes to use at school before and after the visit to the mine. Each class made their own wormery as a part of their study and kept it in the classroom. This enabled the students to view their earthworms’ activities closely over a period of time and to understand why their presence in pasture and gardens is so beneficial.

On the visit to the waste rock embankment each group took part in activities at the worm "farm’ area and on the embankment itself.

As the waste rock embankment is built up the bulk fill is covered with a layer of subsoil one metre in depth. Over this a 100mm layer of topsoil is spread and then planted with a mixture of pasture grasses. The topsoil tends to contain a low earthworm population. In order to improve the pasture’s productivity, earthworms are introduced to the rehabilitated areas by placing sods from an area with a high earthworm population onto the new pasture. The sods are laid upside-down on the embankment at 10 metre intervals in a grid pattern. Lime is sprinkled under and around each sod.

Good pasture can support large numbers of earthworms, from 600 to 1000 per square metre. Adequately earthwormed pastures have almost as much weight of earthworms beneath the soil surface as animal live weight grazing the pasture. There may be 7 tonnes or 20 million earthworms in one hectare.

Given time, the earthworms in the rehabilitated waste rock embankment will spread out and multiply. One earthworm will spread one metre in a year and, under favourable conditions, will produce between 50 and 60 cocoons per year. On average, three earthworms will hatch from each cocoon.

Worm seeding in association with the six local primary schools has taken place at the Martha Mine in the past in 1992 and 1994. This has been carried out under the guidance of Paul Gregg, Associate Professor of Soil Science from the Institute of Natural Resources, Massey University.

Click here to view the unit of work prepared for students who helped with worm seeding.

Click here to read the feedback from students.