Aeration is almost certainly the most important single operation in greenkeeping - rivalled only by mowing, which it predates in antiquity, if we exclude rabbits, sheep and scythe. It is equally the most hated by golfers! Not even top-dressing arouses the most wrath amongst golfers of all ranges of ability.

Few golfers have any understanding of the reasons behind piercing turf with steel! Unsurprisingly, no one has discovered a way to make deep holes in fine turf without some surface disturbance, though this has been much reduced in recent decades by improvement in both machines and techniques.

Few operations show greater or more varied benefits than aeration, though why we use this term when the introduction of air into soil is only one benefit from a list as long as your arm. This list includes relieving compaction; restructuring deflocculated soils; improving drainage; break down thatch by oxidation; correcting stagnation; building up a healthy aerobic soil micro-life; encouraging deeper rooting grasses and thus drought resistance; curing dry patch; helping the absorption of top dressings without layering; and increasing turf resilience.

Few if any of these benefits are known to the average golfer. Sensible management practice avoids disturbing course presentation before major events on the golfing calendar but there is inevitably a clash between optimum soil conditions for aeration and members' enjoyment of the course. I will always cherish the exchange between an irate golfer and the head greenkeeper on a course I was visiting, who demanded "Can't you leave the (adjective) greens alone for five minutes" to which his reply was "Certainly Sir, if you stop playing on them".

I do not propose to debate the relative merits of either the various types of aeration nor the machines to carry them out, except to say that shallow penetration aimed at minimising surface disturbance gives poor results and that the depth must be varied. Ever since the early machines started to replace a line of brawny greenkeepers working back over greens with hand forks, the problem was to achieve depth with speed. Seventy years ago, there was no money to buy powered machines and none to pay for the necessary research to design them. I well remember thirty odd years ago challenging those pioneers of aeration, Sisis, to produce an aerator that could penetrate 5 inches or more, and aerate a green in an hour but to cost less than £500. There are still a few of those Autocrats working, though not I think any longer on golf courses.

Prior to the introduction from Holland of the Vertidrain which I first used there on golf greens in 1980 (it was designed for football pitches) we had no method of really deep aeration of greens except by taking heavy-duty, tractor-mounted fairway slitters over them. I well remember a party of Swedish greenkeepers visiting St. Andrews, watching with incredulity Walter Woods using an Autocrat on dry areas of fairways to hollow tine prior to using wet agents and the heavy duty HA6 fairway slitter on the big greens whilst at the same time he had been plugging to rye-grass patches with a hole cutter on raised areas of the greens. This rye-grass came from many years earlier when the wrong seed was used to patch droughted areas. "You use the greens slitter on the fairways, the tractor mounted slitter on the greens and you cut your holes on the top of hills"

Varying the depth of aeration is very important to prevent pan formation at the depth of the machine - akin to the creation of a plough pan in agriculture. Certainly shallow micro-tining in dry periods can be defended in that it helps penetration of irrigation and wetting agents but it is harmful unless balanced by really deep aeration. This is turn must be done when the soil below is dry and friable, yet one sees Vertidraining being carried out in winter with saturated soils, just because it will not offend as many members. On heavier soils, especially, the holes just fill up with water - benefit, nil! One must deep aerate with lifting action when the soil is dry and friable giving maximum sub-surface cultivation with minimum surface disturbance.

It is a serious mistake to Vertidrain with one eye on the golfing calendar. The ideal time might well be September for the aeration benefit but not for the golfer. Therefore more and more clubs are opting for Vertidraining in August - when often the course is less busy than later in the year - but in any case the golfer must put up with some inconvenience for the sake of better conditions later.

The only close season for aeration is when the soil is too soft to take heavy machinery without tyre marking or the subsoil too wet for it to fissure and restructure under cultivation - which is most of the winter. In such circumstances deep slitting is the answer, certainly not to abandon all aeration.

No one can cope with all the carried types of aeration so we need a range. Having your own machines, including a Vertidrain, means that work can be carried out at the correct time and not at the end of a contractors queue.

A little forethought on timing plus fully informing the members as to why some disturbance is unavoidable but necessary, can avert some grumbles but it is worth nothing that a sensible all year round programme including periodic really deep aeration can save clubs a lot of money. The current vogue fostered we have to say by contractors looking for work for the rebuilding of old greens to perched water table specifications is an expensive remedy and bearing in mind how weird some of these specifications are, some of the remedies may be worse than the original problem.

Where the original construction produced acceptable (or better) results in playing conditions prior to the golf boom of 30 years ago, failing only under heavy winter play, then regular deep aeration and better draining, eg. mini-mole ploughing will nearly always resolves the problem. In most cases in my experience, complete rebuilding is not necessary and in any case unless you rebuild them all how do you avoid having one or more greens quite out of character from the rest? The worst cases demanding relaying are all too often new ones where poor root zone materials were used just to save money. This includes pure sand greens - an anachronism which have a place, if at all, in severely arid desert conditions, where the grass has to be grown hydroponically, ie. artificially, with gross levels of irrigation.

The answer to the question as to when to aerate is simple, namely all the time, whenever soil conditions are suitable, ie. dry and friable, maximising the benefits. On the flip side one has to balance the temporary disturbance of the putting surface caused by really deep but essential aeration together with the risk of wheel marking on soft greens, against the complaints of members and time the operations tactfully - in other words it is all a question of balancing benefits against grumbles. As in all things, explaining the reasons well in advance as an alternative to presenting players with a fait accompli may leave the majority with the feeling that it was not half as bad as they had feared!