E-rays (Erdstrahlen in German, or Earth rays) are said to be evil rays emitted from below ground and detectable only by dowsers with paranormal powers. These evil rays are invisible and undetectable by ordinary people using ordinary scientific equipment. E-rays are blamed for everything from cancer in humans to wilting in plants. E-rays are especially bad for one's aura.
The belief in E-rays is especially popular in Germany where some people sleep with protective sheets of black plastic under their beds for protection. Specialists in E-ray detection practice a German variant of feng shui, advising individuals and government employees on safe furniture arrangement.
Earth radiation is a theoretical geophysical phenomenon described primarily by the German authors Manfred Curry and Ernst Hartmann. They both describe a mystic force field (similar to Odic force, Mana, Qi) that covers the earth at regular intervals and can be detected by dowsing using a divining rod. It is not supposed to be detectable by common scientific instruments but some still connect it to telluric currents, which are actual phenomena, detectable by scientific instruments.
Placing people or other living things in certain spots of the earth radiation knots is believed to be beneficial/harmful depending on radiation flow direction. It connects to the Gaia philosophy and vitalist school and is very popular in certain New Age circles in Europe, especially in Germany.