If Localised Dry Patch is the worst of the endemic disorders in bowling greens that have been mis-managed over the last 3 or 4 decades; then it only just beats low Cation Exchange Capacity (CEC) as the most devastating of problems.
CEC refers to a chemical process that occurs in the soil of healthy living greens and describes the process by which positively charged nutrient ions (cations) are attracted to negatively charged soil particles. This is the soil’s method of retaining the essential nutrition required by the plants and is effortlessly achieved by healthy living soil.
However, in the desert sands of most UK bowling greens, CEC is usually very low indeed and nutrition is scarce.
The thinking outlined in Performance Greens a practical guide is based around a program that can be followed to allow new organic matter to be generated by the green itself; partly through the natural breakdown of thatch by soil micro-organisms and partly (due to the scale of the problems) through inputs that we add to help the process along. And of course we must help the process along as nature isn’t usually in a hurry about these things. Incidentally we can learn a lot from this; mostly that we should be taking a very long term view of green maintenance. However, we must of course provide a decent surface during the transitional period to make sure we still have a bowling club at all.
So what can we do about increasing CEC?
Firstly it is imperative that we stop the madness of the sand, or the blind adherence to the application of high volumes of sand dominated top-dressings every year; I can’t stress this strongly enough; it MUST stop if you are to have any chance of improving your green.
Secondly we must increase soil oxygen by removing excessive thatch, relieving compaction and carrying out regular aeration.
Only then can we think about trying to help increase CEC through artificial inputs. One of the ways we can do this is to introduce CEC boosting materials such as zeolite. This is a natural mineral product that can help to retain moisture and increase CEC in the soil.
Incidentally a basic understanding of the CEC process can help us to get our heads round the general approach we should be taking to turf nutrition and dispel some more of the myths that result in the overuse of fertilisers at many clubs. In particular it is important to understand that some of the essential nutrients, Nitrogen in particular, are available to the plant as negatively charged ions (anions) and this is why we have to add Nitrogen more frequently than most other nutrients; negatively charged soil particles repel negatively charged ions. This means that nutrient anions are either taken up by plant roots or leached from the soil. This demonstrates irrefutably that it is pointless to over apply Nitrogen unless you have a penchant for contaminating your ground water with fertiliser and/or throwing money down the drain.