Michael Hurdzan's "Golf Greens, History, Design, and Construction" is a good read that illustrates how orthodoxy is often based on pretty shallow, flimsy, even fictional foundations.
Regarding the USGA spec, Hurdzan recounts how in 1989 the USGA publication on recommended method of green construction claimed to have studied "carefully over the years" the specification for an intermediate sand layer and "now definitely concludes and POSITIVELY RECOMMENDS INCLUDING THE INTERMEDIATE SAND LAYER IN ALL USGA GREEN SECTION GREENS. It is an integral part of the perched water table concept. Its function is undeniable, and serious functional consequences may result if it is eliminated. Failure to follow the requirement means you are not building a USGA Green Section Green. . . The interface between the course sand layer and the 12 inches of upper soil mix acts as a check on the downward movement of non-capillary water". Yada Yada Yada.
For the next three years, the USGA Green Section came under extreme pressure to justify the 1989 recommendations. But it couldn't. In fact, the Cornell professor of soil physics the USGA ultimately hired concluded that the ONLY function of the intermediate sand layer is to act as a gradient separation between the topmix and gravel drainage blanket and not to perch the water table, a complete reversal of the 1989 dogma. Hurdzan notes that if course gravel is used for the drainage blanket, it is probable that there is a need for the intermediate layer (to prevent the layers from mixing) but, as a practical matter, "golf course architects and contractors try to avoid the need for the intermediate layer (by using a finer material for the drainage blanket) because it is expensive and time consuming, and adds nothing to the performance of the green."
But even after this research, Hurdzan writes that one huge question remained unresolved. Is there a water table that can act as a water reservoir for plants growing in the topmix? Hurdzan goes into considerable detail on the subject, and concludes the answer is, "PROBABLY 'NO', or that the effect is not enough to be of any real value".
As you probably all know, in addition to being a well known golf course designer, teacher and writer (courses include Devil's Pulpit in Ontario and Bully Pulpit in North Dakota) Hurdzan spent years as a superintendent, and has a doctorate in plant physiology to go along with a masters degree in landscape architecture. Presumably he knows a little something about scientific method.
Does anyone know if the USGA has tried to rebut any of this?
Hurdzan's Chapter 9 Postscript, on his personal experiences building greens, contains a noteworthy anecdote. He recounts after having replaced an old soil green with a high sand green at a well known Ohio club, the superintendent said the club would like to make some of its older greens larger. Hurdzan said "let's find some places for temporary greens and start getting them ready" but the superintendent said there'd be no need for temps, they'd just continue to use the green they had but rope off the areas newly constructed.
Hurdzan asked if he wanted the new part constructed out of soil like the old green but the superintendent said, no, to go ahead and build it out of 80/20 sand/peat like the new green Hurdzan had just built. Hurdzan began to "scientifically" explain all the reasons why the result would be a maintenance and performance nightmare, when the superintendent interrupted him and said, "Come with me." He took him out to a nice big green on the course and said, "OK, Dr. Architect, tell me what you see about this green." All Hurdzan saw was a nice big green. As it turned out it was half native soil and half 80/20 mix. Hurdzan further learned both halves were maintained exactly the same, same watering, same mowing, same topdressing, same fertilizing, same pesticides, same aerification and verticutting.
Still somewhat incredulous, Hurdzan offered that it must play differently so they had a member hit shots to all portions of the green and putt on the green but he could find absolutely no difference in playability. So he did what the superintendent suggested and the new, enlarged greens worked out just fine. Years later he did it at several other clubs with small budgets, all with good results. He doesn't advocate doing it, because he is concerned that it won't work in every case, but the point is that after a few years of maintenance practices, the construction of a green may have little or no effect on its performance or its playability.
In my area, over the past fifteen years, I know of six courses that built or rebuilt a number of greens. Three went with the USGA spec while the other three were pretty much home cooked. Without a shadow of a doubt the USGA spec greens have performed miserably compared to the home cooked greens. Grow in was a nightmare and in some instances it would be no stretch to say that the greens failed. The spec never gets criticized, though. Rather, the excuse is usually that the spec wasn't followed close enough and the fact the other non-USGA spec greens performed well is attributed to luck.
Has the hallmarks of orthodoxy, no?