The term aeration aptly implies the result of the procedure: exposing the lawn's soil to air. However, the aeration's purpose is not to allow air to reach the soil, but to allow water to reach the soil. When a lawn's soil become overly compacted or develops a thick, underlying layer of material, called thatch, water cannot easily penetrate the lawn's soil. Aeration breaks through compacted soil or thatch by simply poking holes through the grass or removing small, cylindrical plugs of grass and soil.
Manual Plunging Aerators
Simple and effective, manual plunging aerators consist of puncturing tips attached to a T-shaped handle. The two general types of plunging aerator tips are core tips and spike tips. Core tips look like thin cylinders and spike tips resemble large nails. Whereas core tips remove a cylindrical plug or soil and grass from the lawn, spike tips simply puncture the lawn's surface. The operation of both types of manual plunging aerators is simple: the gardener grasps the T-shaped handle and plunges the tips into the ground.
Manual Rolling Aerators
The wheel-mounted, cylindrical aeration roller and attached handle of the manual rolling aerator resemble the form of a traditional, reel-type lawnmower. As with a reel-mower, the gardener rolls this type of aerator across the lawn's surface. Core- or spike-type aeration tips protrude from the aeration roller and continuously puncture the soil as the gardener moves across the lawn.
The ride-atop aerator looks similar to a riding lawnmower. However, rather than cut grass, the ride-atop aerator removes plugs of soil with core-type aeration tips. Like the manual, rolling aerator, the ride-atop aerator's core-removal tips protrude from a cylindrical roller. Whereas most manual aeration tools simply toss pulled cores onto the lawn's surface, the ride-atop aerator transfers the cores into a container for easy disposal.
Wheel-mounted Aerator Chains
Typically mounted to the wheels of a riding lawnmower, aerator chains are similar in concept to snow tire chains. However, unlike the link-style chains used to drive through the snow, aerator chains add a series of sharp spikes to a vehicle's wheels. Mounted to a riding mower, the chains puncture and aerate a lawn as the mower cuts the grass.
Attached to tractors or mowers via hitch, the tow-behind aerator consists of a set of rolling spikes or core-pulling aeration tips mounted to wheels. Core-pulling tow-behind aerators typically have a large bucket mounted above their wheels to catch and store the pulled plugs. As with wheel-mounted aerator chains, attaching a tow-behind aerator to a riding mower combines aeration with regular lawn maintenance.