Once land was cleared for production agriculture, native earthworms quickly disappeared.

New Zealand scientists have had a unique opportunity as far as earthworm research is concerned. Birds are well known predators, but native earthworms are also food for endangered and endemic land snails.

Providing food for predators: Earthworms, like all creatures, are part of food webs.

Burrowing also improves soil aeration (important for both plants and other organisms living in the soil) and enhances plant root penetration. This brings water and soluble nutrients down to plant roots.

When earthworms are introduced to soils devoid of them, their burrowing can lead to increases in water infiltration rates of up to 10 times the original amount. They open up small spaces, known as pores, within the soil.

Improving soil structure: Earthworm burrows alter the physical structure of the soil.

Earthworms also take nutrients down through the soil profile, bringing them into closer contact with plant roots. Scientists have measured up to five fold increases in nitrogen availability in earthworm casts compared to undigested soil. Nutrients like phosphorus and nitrogen become more readily available to plants after digestion by earthworms and being excreted in earthworm casts.

Increasing nutrient availability: This happens in two ways: by incorporating organic materials into the soil and by unlocking the nutrients held within dead organisms and plant matter.

Most people know about earthworms and compost, but earthworms do the same in pasture soils, decomposing dung and plant litter and processing 2–20 tonnes of organic matter per hectare each year, and recycling leaf litter under orchards and in other forested areas.

Recycling organic material: Earthworms, along with bacteria and fungi, decompose organic material.

Earthworms influence (and benefit) the soil ecosystem in a number of ways:

Download biggest earthworm in the world