The Groundsman

October 2014

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TECHNICAL UPDATE 36 the Groundsman October 2014 Visit www.iog.org for more information and digital editions outine deep scarification and solid tine aeration in annual end-of- season pitch maintenance can help limit the accumulation of thatch and improve rooting depth. When the problems of thatch and layering in profiles are greater and more entrenched, other treatments are required. Aeration in cricket can be effective in problem solving (as opposed to prevention) but it is not always effective. So, it is important to determine whether a problem exists, whether aeration will help and which aeration approach or equipment will help. Why is aeration necessary? The grass plant plays an important role in a cricket pitch. The above ground parts (leaves, crowns and stolons) affect ball seam and spin. Below the surface, the roots help to bind the pitch together, helping it resist cracking and wear. The Cranfield-ECB Rolling guidelines show that plants have a role in drying pitches at depth, which helps the soil to shrink and the pitch to become harder. To thrive and to regenerate from the wear caused during play, the grass plant needs to obtain water, oxygen and nutrients from the soil through its root system. Above the surface, plants produce sugar through photosynthesis, take in carbon dioxide (CO 2 ) and give out oxygen (O 2 ). Below the ground, the plant roots respire, taking in O 2 and giving out CO 2 . For healthy grass growth, it is essential to provide enough oxygen in the soil while not poisoning the plant with carbon dioxide. Soil is porous, with small interconnected pores between clay R Aeration guidelines – Part 4 In Part 4 of our aeration guidelines, TMGS' Dr Iain James offers an insight as to why aeration is necessary By: Dr Iain James aggregates and other soil particles such as sand, silt and organic matter. The packing of the soil particles and aggregates can be measured by the dry bulk density of a soil (the mass of soil in a fixed volume). As the density increases, the percentage of pores decreases as more soil particles are packed in. Dry bulk density in cricket pitches can range between 1.4 g/cm 3 (club pitch, small roller) and 1.8 g/cm 3 (1st class pitch, heavy roller). The total porosity (the volume of pores in a fixed volume of soil) will range from 47 per cent at a density of 1.4 g/cm 3 to 32 per cent at a density of 1.8 g/cm 3 . Grass typically requires a minimum of 10 per cent air-filled porosity, which doesn't leave a lot of room for water. In reality, in compacted cricket soils, air-filled porosity is much lower than 10 per cent and when the pitches are very wet can be close to 0 per cent. It is not just the total volume of pores that changes; as the soil is compacted, pores become smaller and less well connected. This slows down the rates of transport of soil gasses and water. Smaller pores are more likely to be filled with water and will quickly be exhausted of oxygen and filled with carbon dioxide. The plant will respond with shallow rooting (being nearer the surface air supply) and poor growth. Why might aeration be unnecessary? During the research, it was often found that despite being subject to frequent rolling the control plots (the plots not receiving any aeration treatment) performed just as well as any of those that underwent the aeration treatments. This does not mean that aeration is not worth doing, but it highlights a big difference between the aeration of golf greens and the aeration of cricket pitches: most cricket soils shrink and swell (hence they crack), whereas the sands used in golf greens do not. In sandy soils, compaction is a one- way process; the soils become more and more compact until they are mechanically loosened. In the clay loam soils used in cricket in this country, the clay minerals shrink and swell as they dry and wet, meaning that these internal soil forces can help to structure the soil and create a connected pore network. This can reduce the need for aeration but can cause other problems related to cracking and root breaks. Guidelines for aeration The Guidelines for Aeration are based on detailed independent research, and they will help you select and use the right aeration method to help improve your pitches. The guidelines are in two main sections - routine aeration to help prevent pitch problems and using aeration to help solve pitch problems. The purpose of the guidelines is to advise when to aerate, which tool to use and how to maximise the benefit of the operation. This is not a prescriptive set of instructions but they challenge groundsmen to take the problem-led approach to: • Investigate and identify the problem • Select the most suitable and cost- effective techniques and machinery • Carry out the work in a timely fashion, and

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