Does soil affect magnetism

Answer 1

Everything affects magnetism, simply because all things have magnetic properties (which are a product of atomic motion). But yes soil contains iron, and often in a highly magnetic form, magnetite or maghaemite or magnetic iron sulphide (you don't need much of either to make an appreciable contribution- try just running a magnet over some dry soil, or mixing soil with water in a glass jar, and tape a magnet to the outside). The principle way in which soil 'affects magnetism' is via its effect on the Earth's geomagnetic field, that's how geophysicists find buried archaeological sites using magnetometers. That is where people lived in the past, or dug holes, or lit fires they often leave magnetic 'evidence'. To follow up the topic further you need to look up 'magnetic susceptibility' which will explain the magnetic properties of material, i.e. how magnetic (or not) they are). As a guide air is '0' on the SI scale water slightly negative (diamagnetic), a typical soil may be in the tens, or even hundreds, especially if was formed from igneous rock, or has been burnt. Any it's a huge topic, good luck!