A method for cleaning and conditioning air in which the air is first passed through or along water in a reservoir, then passed through a layer of soil to clean and condition the air, and then passed through a layer of a germ-reducing material. In a preferred embodiment, a drainage network of individual cells is created for the geographic region. The stator structure includes stator-electrode strips on a stator cylindrical surface. The biasing mechanism is configured to bias the link member such that the movable member is disposed at one of the retracted position and the extended position. The reference signals utilized to characterize the SSI may be limited to a determined range. The gearbox restrain extends outwardly from the seeding machine and engages the flexible rotatable drive shaft receiving portion.