The Groundsman

April 2016

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Visit for more information and digital editions TECHNICAL UPDATE 32 the Groundsman April 2016 et's go back to the biology classroom and refer to the photosynthesis formula: carbon dioxide + water + sunlight → + oxygen. It's the reverse of respiration; plants convert the energy in sunlight into chemical bonds of sugar. When cells respire they break these bonds to release energy. Photosynthesis produces oxygen as a waste product therefore plants can use the oxygen that they produce during photosynthesis. Plants only perform photosynthesis in the green parts like leaves and stems, however all plant cells need oxygen to respire. So cells in the leaves get plenty of oxygen, however cells in the roots need to get oxygen from the environment to stay alive. Even though roots are buried, they can absorb oxygen from the small air spaces in the soil. Without these root cells the rest of the plant dies. So when our soils are water logged, compacted and anaerobic our sports turf grass cannot perform to its optimum. Creating a perfect environment With our refresher biology lesson in mind we can consider what our soils need to create the perfect environment for strong healthy roots for our turf grass to survive and in turn create the best playing surface. Traditionally turf managers have used mechanical aeration. These methods still play a significant role in good management of sports turf. They can be effective and especially when used in conjunction with chemical aeration as a combined tool. L Why do we aerate our soils? David Snowden takes us back to school for a biology lesson to help understand the importance of oxygen in soil By: David Snowden We want our soils to become more efficient and balance our soils but physical aeration alone cannot do this. With turf professionals there is also pressure which means that physical aeration is inconvenient and disruptive to sport. Life is a balance and that also applies to the soils in which we grow grass. In an ideal world we would have 50 per cent soil, 25 per cent water and 25 per cent air. Unfortunately air (oxygen) is frequently lacking in our soils. So we need our soils to be more aerobic and mechanical aeration is not always sufficient or problematic. Plus these methods can be expensive and do not always cover the entire playing surface. Effective aeration Aeration is all about reducing compaction and increasing the percentage of oxygen to the rootzone. Why? Well, we need to think about the different forms of bacteria in our rootzone. There are thousands of different forms of bacteria, but just three basic forms of bacteria which we as turf managers are interested in. Those which use oxygen to be prolific (aerobic). Those which can survive in low or oxygen-rich environments (facultative anaerobes) and those which do not use oxygen (anaerobic). The more air in the soil, the more prolific the aerobes will become.These in turn consume oxygen for cellular respiration, releasing carbon dioxide (CO 2 ) water and nutrients for roots to use and drink. We have all seen the benefits of green up around a tine hole, this is the result of oxygen using microbes becoming more prolific. They in turn produce CO 2 and solubilise nutrients for root uptake. We can now produce this effect over the whole surface on a regular basis with multiple rewards to the turf manager. Remember, plants receive up to 80 per cent of their CO 2 requirement from the soil and this can only be achieved in well aerated soil. Also aerobic bacteria out-compete pathogenic bacteria, this results in less disease pressure. We all know that anaerobic soils are not efficient and can result in a condition known as black layer when the rootzone smells like rotten eggs. An example of a highly efficient aerobic rootzone

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