Tuesday, September 04, 2012

Turf Toughie: Take Our One-Question Exam!


Q: Why is it important to maintain your soil pH between 6.5 and 7?

            Sometimes it’s the simple questions – like “Why does my belly growl when I’m hungry?” that are quite perplexing but also most important. Same goes for turf.
             
“Why is it important to maintain your soil pH between 6.5 and 7?” is one of the questions Benjamin A. McGraw, Ph. D., associate professor of golf and plant sciences at the State University of New York (SUNY)- Delhi, N.Y., likes to pose to his students. 

“I don't know if it’s a head-scratcher but the answer is important and vital to a superintendent’s career,” McGraw says.

The answer, as McGraw explains, is that most nutrients (whether applied or in the soil) are readily available to the plant in this pH range. Outside of this range many nutrients (both macro- and micro-nutrients) are not readily available to the plant.

So… keep the pH up and don’t leave your plants with their bellies growling!

2 comments:

Micah Woods said...

I would suggest that turfgrass can perform well and have adequate nutrient availability in the pH range from 5.5 to 8.3. The 6.5 to 7.0 range is not supported by research. I wrote some more about this on my blog:

http://www.blog.asianturfgrass.com/2012/09/why-it-is-not-important-to-maintain-soil-ph-between-65-and-70.html

Anonymous said...

Well now, a most interesting post and comment. May I inject a comment as a professional with decades of professional practice -- who has actually had to provide demanding Tour championship conditioning of fine turfgrass consistently?

Both of you make excellent points. And as you guys know, in the real world the management of turfgrass is not done in a laboratory or on turf plots, but rather one that deals with a hand that is dealt with multiple cards.

I have had the demanding task of dealing with the preparation of a WGA championship and finding pH at 5.2. At such a low pH (even in a lab) aluminum (Al) is neatly released and becomes available (dissolves) in the soil solution to replace phosphorus (P) (restricted at low pH) and that low pH can indeed be very detrimental -- it is a wonderful root pruner. And surely when pH begins to approach 7.0 and significantly above a professional agronomist must take such factors into consideration and explore other critical factors beyond pH alone. pH, after all, is just one measurement among many for a professional practitioner to consider. Good management is like a good puzzle -- you have to check all the pieces and finally know how the fit together. And no two puzzles are the same.

Certainly, and I am sure you both would agree, as pH rises to 8 and above, one should rationally ask more about what is going on. Other chemical matters can be at play such as carbonates and bicarbonates or sodium (Na) that must also be dealt with.

I have had great turf at above 8 and struggled with soil factors affecting turf growth at 7.2. pH does not alone make things impossible or superb. It is certainly an important one though. And if someone gives me a choice -- I'll take slightly acidic any day of the week particularly on cool season turf.

All of this is not brain surgery and really we unwashed, non-Ph.D's can indeed have a deep grasp of things as well -- years of field experience are invaluable to gain wisdom beyond wrote.

No medical physician whom I would employ would focus on a single test in developing a prognosis, but would conduct many with some leading to the need for others. And the best weigh multiple factors and attribute health to no rigid range of a single factor. God has provided great diversity in nature that permit organisms to adapt to varying varying factors after all.

Good practitioners are aware of these multi-dimensional aspects of life and appreciate stimulating differences of opinions.

As in a military war never assume, never base battle strategies on a single, narrow factor, ask many questions, pay attention to the minute, but act on the overall.

Thank you,

James G. Prusa
SKY72 Resort -- Korea
jgp@alumni-gsb.stanford.edu