works in a beneficial way


This may be the real reason that aeration


football games, the visual appeal of the sports turf is often the target of commentary, and viewed as a key indicator of the health and condition of the turf.


In interpreting the results, Dr. Gange


stresses that oxygen is a huge consideration, in that unchecked compaction will prevent root growth by causing a shortage of oxygen in the soil and preventing it from being able to filter water down to the root zone. “Once a root zone becomes anaerobic, anaerobic bacteria will flourish, and generally they are toxic to plant life,” he says. Dr. McGregor believes that the key is


the prevalence of macropores versus micropores in the soil. “The larger the size of the pores, the more ‘connectivity’ between pores and the greater the ability of the soil to permit gas exchange and water percolation. This may be the real reason why aeration works in a beneficial way in microbial communities,” says Dr. McGregor. “These larger pores also help prevent run-off of water and make irrigation more efficient.” Clays, which have more micropores and fewer macropores, tend to have more physical barriers set up in the soil structure that may prevent bacteria from getting to the organic matter to degrade it. “When you aerate with the Verti- Drain, you’re loosening up the soil so you encourage this connectivity of pores,” he adds. Also, clay soils require a greater frequency of aeration than sand- based soils. In the experiment, oxygen concentrations varied from area to area – likely because pore size and connectivity differed from one area to another. And from season to season, oxygen varied because of differences in the biota (“the


Biolog Community Level Physiological Profiling (CLPP): The Biolog technique involves the use of a rectangular plastic dish with 96 wells in it. Each is filled with a different carbon-based compound known to be useable as food by a certain species of bacteria. The wells each contain a dye that, upon exposure to carbon dioxide, turns blue. The blue colour means the bacteria added to the wells were able to use that substrate (food) and to respire. This approach gives researchers billions of different combinations; every species of bacteria has a different substrate it can use so Biolog is useful for species identification and community profiling. Patterns are established by observing which wells are used and which aren’t.


Phospholipid fatty acid analysis (PLFA): The Biolog analysis relies on the notion that the bacteria you have in your soil can use one of the compounds in the wells; but they may not. PLFA is now the technique of choice for community profiling because of its accuracy in identifying bacteria and fungi based on the


living things in the soil”) including roots, earthworms, bacteria, and other life forms. It is this interconnectedness that reinforces the concept of “soil habitat” to explain the dynamic aspect of such interactions. Dr. McGregor: “This experiment indicates that encouraging development of microbial communities, particularly aerobic ones, is in the best interest of the average turf plant. Aerobic microbes are more metabolically productive. The chemical reaction that goes on within the respiration system of an aerobic microbe creates more energy, whereas an anaerobic microbe does not use oxygen and cannot achieve the same level of efficiency. The soil habitat is literally a healthier one with such an enriched energy budget.” The greater the number of aerobic


microbes in the community, the greater the level of biological processes that are possible: decomposition and nutrient cycling go hand in hand with re- mineralisation. “Enhancement of plant growth is also going on, and it can be either direct or indirect,” Dr. McGregor says. “And the natural competition between microbes, aerobic versus anaerobic, can have a useful effect against pathogens that could harm turf plants, since some microbes in the soil produce antibiotics that are antagonistic to the pathogens.”


One of the most important findings of


Dr. McGregor’s work is the revelation of the transient benefits of aeration on microbial communities. “The benefit doesn’t last when compaction returns. Sports turf is subject to compaction on an ongoing basis, and so the benefits of aeration are only sustainable when the activity is routinely repeated. Without it, microbes can go into a kind of


fatty acids in their cell membranes. These fatty acids differ from one microbe to the next and from one bacterial group to another (aerobic and anaerobic). The test entails extracting fatty acids from the soil and running the samples through a gas chromatograph (GC) to measure the abundance of different fatty acids. Data derived from PLFA is used to calculate bacterial to fungal ratios; determine the stresses to different types of microbes; and various other types of information.


Dilution Plate: Dilution Plating is an old analytical method indeed; it’s done by school children all the time in science class. It involves using an agar (an algae extract used as a culturing medium) to see if the bacteria or fungi in a soil sample will grow in a dish. Though simple to do, the problem is that you’re only using one agar per dish – and the odds of growing multiple microbes on one agar are very slim. Only 1% of soil bacteria are able to grow on any known medium so, at best, Dilution Plating allows you to record only 1% of the soil’s microbe population. And


Due to the expertise of its faculty, the Royal Holloway ranks among the top university research departments


hibernation if they are deprived of the necessary access to oxygen and water.” The conclusions from this significant


research study are important for turf care professionals. A quarter-century of worldwide use of the Verti-Drain convinced us at Redexim, as well as our numerous customers, that the Verti-Drain worked. Now we have a clearer understanding of why this is so. Although science isn’t always a neat and tidy process – at times it does seem to creep forward rather slowly – Dr. McGregor’s findings are a cause for hope. By understanding that much more about how the Verti-Drain affects soil physical characteristics and microbial community structure, we are more confidently able to explain the science behind a practice that simply works well. As additional scientific work is conducted, we look forward to sharing it with you to help advance this field of study and the practice of aeration that is such a huge part of our collective work.


Redexim Charterhouse would like to thank the Royal Holloway, University of London, and in particular Dr. Donald J. McGregor for preparing his thesis on this important subject.


yet virtually all sports turf studies of the past used this technique. For the average green keeper or grounds manager, it provides a basic level of data for a very low price. But it’s not accurate enough for more sophisticated scientific studies.


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