The experiment took three years to complete and six months to write


A variety of tests were performed on the football pitches and golf course test areas by Dr. Don McGregor


At some point, turf professionals should consider erecting a statue in honour of microbes for their highly effective and productive contributions to a remarkably complex habitat.


The dilemma of conventional wisdom: “We know it works, but ... why?”


Aeration certainly isn’t new. For most of this century, mankind has been poking holes in the soil based on the belief that it helped the grass grow. A key point that should be addressed is the notion that “aeration” is all about “pulling cores.” Simply put, it’s not. Aeration is really the technique, not the machine, and there are a great many ways to aerate, each with its own advantages and disadvantages. What turfcare professionals have known for years is that the Verti-Drain works, but no one could really provide the scientific reason why. The soil habitat concept introduced earlier by Dr. McGregor proved to be as enigmatic for those who care for turf on a daily basis as it was for those who studied it in a lab. Clearly, aeration was a popular cultivation practice, but how strongly rooted was it in biological processes? When a tine breaks the soil surface, penetrates down to a desired depth, and performs its characteristic “heaving” motion, what is happening from a biological standpoint, and how and why does that affect turf health? Even the manufacturers of the Verti- Drain, could only point to conventional wisdom.


This dilemma recently attracted the attention of the academic community, specifically Dr. Alan Gange and Dr. McGregor at the Royal Holloway, where the Department of Biological Sciences is one of the largest in the college. Some 40 faculty members and about 400 students there routinely explore timely issues in biology, ecology, zoology, biochemistry, and molecular biology – with many research activities yielding


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practical applications that benefit businesses, consumers and the environment. While Royal Holloway isn’t the first institution to delve into research on microbial activity by any means, it has taken on the task with a rather unique twist. Rather than simply counting the total number of microbes in the soil (the most common practice for studies of microbes), their research involved analysing the composition of the soil’s microbial community – exploring in the process whether or not aeration had an effect on that community, in particular, the “good” aerobic microbes with the potential to benefit turf plant growth. “I’ve given lots of turf talks in the past, usually on environmentally friendly products which are designed to increase microbial populations,” noted Dr. Gange. “What really caught my attention was when people I spoke with told me that many of these were not all that effective. It led me to believe that one could probably get the same effect, increasing the good microbes in the soil, by simply aerating it. So I approached Redexim, to see if they were interested in helping us determine if that statement were true.” According to Dr. Gange, this is the only study done that attempts to link aeration to the numbers and diversity of the microbial community in the soil. “Ecologists couldn’t look at the diversity of the microbes before because the technologies were not really available until the last few years,” he said. “So, we’ve had 10 years of just counting the numbers of microbes without anyone profiling the composition of that community in the soil. And no one’s made the connection to aeration before.” While Dr. Gange may have started the


ball rolling, it was Dr. McGregor who chose to do the research for his thesis publication “The Effect of Cultivation on Microbial Communities in Sports Turf Soils.” The research experiment took three years to complete and nearly six months to analyse and write up. The results are extremely useful for anyone responsible for the care of turf grass on sports fields or golf courses.


Anatomy of an experiment: Aeration and Microbes


With some assistance from Dr. Gange, Dr. McGregor conducted two distinct trials: one on two clay-based football fields at the school, and the other at the sand- based turf of a nearby golf course, Liphook Golf Club, in Hampshire. Feeling a little like an “environmental detective,” Dr. McGregor designed the experiment in a way that entailed dividing the football pitches into individual plots, some of which were aerated (using a Verti-Drain 7516


aerator) while others were not. Dr. McGregor: “These were pitches that were used by the college football team on a regular basis, and so were subjected to normal or above-normal real world stresses, like any other sports turf.” He added a degree of complexity by aerating with the Verti-Drain at certain times of the year. “Some areas were aerated in spring only, others in summer only, autumn only, winter only, and still other plots were aerated in all four seasons. Our goal was to mimic the combinations of seasonal aeration typically employed by a groundsman,” he adds. A control group of plots on the football pitches were not aerated at all. Like the football pitches, the test area at the Liphook Golf Club was divided into individual plots, with each one coded for a schedule of Verti-Drain aeration (except the control group, which received no aeration) at different times of the year. A comprehensive series of measurements were then taken – of pH, water content, gas content, atmosphere, compaction, and make up of the microbial population and community structure – on all the plots at regular intervals before and after treatments with the Verti-Drain, the exact timing of which depended on the technique and the weather conditions. (In some cases, the frozen ground required a slight adjustment to the schedule, for example). Soil samples were taken and returned to the lab at Royal Holloway for analysis. Some tests were done right there in the field, including those measuring the degree of compaction with a penetrometer.


An important note about the measurements: Dr. McGregor was careful to use a variety of measurement techniques ranging from simple soil probes for measuring atmosphere to sophisticated approaches never before available, such as phospholipid fatty acid analysis (PLFA), the technique of choice today for calibrating microbial populations and their structure/make up. Some of the measurement and analytical tools used by Royal Holloway are fairly routine and are, in fact, decidedly (and appropriately) low-tech in nature. Others represent the most sophisticated methods currently available – short of DNA analysis, which is prohibitively expensive and subject to contamination – for counting and profiling the complex microbial community in the soil.


Static and dynamic changes


According to Dr. Gange, a variety of soil properties were constantly exerting varying degrees of influence on the soil microbial community, and the turfgrass


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