The steam is produced by propane and injected into the soil. According to Newland, the premise of the soil steamers is to sterilize weed seeds and control soil nematodes with the heat they produce.

The soil steamer’s banded steam design targets the top one-to-two inches of soil, the critical zone where weed seeds germinate, providing an 80% weed control rate for both conventional and ...

This steam soil steriliser was invented and patented by P F Dorey in 1911 and built by John Leale. Tomatoes were brought to Europe around 1500 but were initially thought to be poisonous.