The Groundsman

July 2014

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TECHNICAL UPDATE 25 the Groundsman July 2014 Visit www.iog.org for more information and digital editions trictly, 'aeration' in sports turf management means 'increasing the volume of air in the soil'. It often has a secondary meaning of 'loosening the soil to remove compaction', also known as de- compaction. The aim of increasing air content and removing compaction is to improve soil health, which slows the rate of thatch accumulation and encourages healthy, deep rooted, grass growth – which is essential for good pitch performance. Thatch accumulation in the soil profile slows pitch pace and bounce, good grass coverage helps pace and consistency, and deep rooting helps grass growth and binds a pitch together. Achieving low thatch content and good, deep rooted grass coverage helps to produce good, consistent pace and bounce. Why is aeration necessary? Rollers are used to produce hard pitches because this helps ball pace and bounce, and rolling is an essential part of cricket pitch preparation. But rollers make pitches harder by pushing the soil particles closer together, making the spaces, or 'pores' between them smaller and less inter-connected. This means that air and water are squeezed out of the soil leading to stagnant conditions for grass growth. It also means that the soil has very high strength, making it difficult for roots to penetrate through the profile. In the majority of sports, the turf manager would use tines to lift the surface and increase the volume of air, or punch through the surface to make holes which are then replaced with sand. However, this is more difficult on cricket S Aeration guidelines for cricket pitches The result of four years of research at Cranfield University funded by the Institute of Groundsmanship and the England and Wales Cricket Board, a set of indispensable guidelines will help groundstaff use aeration effectively to improve the quality and performance of cricket pitches and outfields By: Dr Iain James pitches because the soils are hard clays and surface smoothness and uniformity cannot just be ripped up. In cricket, aeration methods are generally aimed at one of the following by making holes in the surface: • To increase the volume of the air in the soil by de-compaction. • To de-compact the soil to help deeper root growth. • To increase infiltration of water into the soil. • To reduce deeper thatch to increase microbial breakdown of thatch by getting more oxygen deeper into the pitch. • To create holes to assist in seed germination. • To bind upper layers to lower layers in the profile. • Scarification (sometimes called linear aeration) is used to remove thatch from the pitch. The research has shown that although these might be the intended outcomes, some of them are not achieved – in fact, using solid tines doesn't de-compact the profile and doesn't help microbes break down thatch. Likewise linear aeration is effective at removing near-surface thatch (scarification) but isn't effective at de- compaction or increasing the oxygen content of the profile either. What the research has shown is that the aeration method needs to be matched to the intended outcome and that timing is critical. If you want to improve rooting depth, then deep solid tines or deep drilling could be of benefit. If you want to reduce thatch content, look at deep scarification. If you want to de-compact the soil then don't worry about solid tines as these will not work, just let it wet and dry naturally and the shrink and swell will help to create natural channels and fissures and reduce compaction. Don't let it dry out too much though because deep, wide cracks can be a problem. [Although the guidelines take a close look at the effect of aeration on cricket square and pitch performance, the guidelines for outfields can be applied to other sports such as football and rugby.] Future Technical Updates in The Groundsman will illustrate how the guidelines will help in the selection and use of the correct aeration method. l The guidelines have been written by Dr Iain James, technical director at TGMS and formerly senior lecturer and head of the Centre for Sports Surface Technology at Cranfield University. He is also co-author of the 'ECB-Cranfield Rolling Guidelines'. About the Author Wiedenmann Terra Spike: one option for aeration

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