Report by IEUAN DAFYDD
For many years the
application of urea buffered sulphur, or similar, to fine turf in an effort to lower the pH of a soil was commonplace, but is ...
Lowering the pH of the soil profile RIGHTor WRONG?
F
or many years the application of urea buffered sulphur, or similar, to fine turf in an effort to lower the pH of a soil was commonplace. The received wisdom seemed to be cast-iron in its assertions: finer grasses thrive in a slightly acidic soil, sulphur lowers pH, ipso facto sulphur is great for fine turf areas, golf greens particularly. It took a while but some bright spark eventually put his hand up in class and said “Please Sir? Are you sure that putting sulphuric acid onto our greens is a good idea?”
Almost immediately the genie was out of the bottle and greenkeepers around the globe began to question the use of such a caustic acidification programme, regardless of the benefits (or otherwise) of acidic soil, the action of applying a dangerous chemical to fine turf was looked at with a frown. Agronomist Robert Laycock was certainly doubtful when it came to acid programmes and penned the following in Greenkeeper International; “The effects of repeated acidification can be seen in many of our old golf courses. Earlier this year I recently received soil samples from the greens of a well-known golf course (not a regular client). The pH values were between 4.4 and 4.8. The turf was annual meadow grass, the rootzone
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anaerobic and thatchy. Experience has taught me that a factor in the development of greens like this is the use of acidifying materials. My recommendation was that the greens should be limed - I do not expect for one moment that they will be. But what would be the adverse effect of liming greens like this? What could be worse than their current condition?” And therein lies one of the major
problems of an acidification programme - it can be overdone very easily indeed. Soil Scientist Stuart Ashworth clarified the point: “Finer grasses thrive at a pH of 5.5 to 6.5, that is a fact. However, the application of a corrosive, toxic chemical to turf in order to achieve this lower pH is inadvisable. Nitric Acid or Sulphuric Acid put into a golf green can easily cause problems - a pH below 5 might well result in unhealthy greens - this is a precise science, not a ‘chuck it and chance it’ affair.” Handling strong corrosive acids and sulphur treatments is, therefore, fraught with problems and can often lead to other problems such as plant scorch and increased severity of black layer. So is the movement towards acidification dead? No, but it probably needs a facelift. The word ‘acidification’ is perhaps too emotive and creates an immediate
stumbling block: once we have ascertained that applying acid to soil is probably not a good idea it would appear safe to assume that acidification of the soil is also a non-starter.
Enter confusion number two - it is actually possible to reduce pH of a soil to the ‘optimum’ pH of 6 without resorting to harsh acids. A new, synthetic product that has
recently been put on the market across Europe - Re-Phlex - replaces products like nitric acid and urea-buffered sulphuric acid without the use of toxic or corrosive harsh mineral acids. What is more, this non-corrosive, non-fuming, 100% biodegradable acid replacement system is a non-skin irritant and non- mutagenic to fish and wildlife. So, several of the problems appear to have been removed from the acidification programmes of the past, safety and environmental issues have, apparently, been addressed. The question remains though, is the reduced level of pH on a golf green a desirable practice?
Laycock maintained that it is not: “Many of the old greens I come across have a turf consisting predominantly of annual meadow grass on soils of pH 4 to over 7. In other words the annual meadow grass seems to do better than
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