.Why is topsoil darker than all other levels of soil?

Mostly this is just the topsoil but it does not reflect the entire soil. ... The topsoil is usually darker than lower layers (or horizons) because this is where organic matter accumulates

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.