A spike aerator work best in loamy soils since the holes made by them are fairly small, and not too deep. However, they can help break up thatch build up. Since the holes are small they don’t seem to last as long as the two other types. The greatest advantage to a spike aerator is that they are very easy and quick to use. Core and stake aerators are great for clay soils. Overtime they strengthen roots to create healthy lawns.
Hand aerators are best when used in smaller lawns or in dry areas of the lawn. Often even people who regularly hire professionals to aerate will have a hand aerator to get the corners, go over troubled areas of the lawn, and do small touch ups. Manual lawn aerators are great for ups and redoing small areas. It could take up to two hours to aerate a medium-sized yard by hand. The advantage of doing it by hand is that it is cheaper plus it will probably take you at least 2 hours to rent an aerator and take it back anyway. Smaller than average yards should be much faster.
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The best manual aerators are core aerators. Two prong are the best.. (3 prong aerators are much harder to use.) The best hand-held aerators will have a foot handle for you to push the aerator into the lawn giving you more leverage with your body weight. Given that extra weight, you should to produce decent cores that will last a long time. To lengthen the effect of aerating, you can add peat moss and gypsum just after aeration to your lawn. In clay soils, core aerators are better than a spike hand aerator.
A lawn expert at the University of Georgia, Dr. Robert Carrow compared the effectiveness of different lawn aerators. He found that core and plug aerators enabled deeper rooting and water extraction of the grass by 25%. A spike aerator has the most effect in a lawn with little clay content. A manual plug and core aerator works like a mechanical lawn aerator. Both take plugs out of the soil which helps the grass-roots to develop and deepen allowing them to find more access to water and other minerals & nutrients essential to a healthy lawn.