organic matter, the three primary nutrients (NPK), the three secondary nutrients (Ca,Mg,S) and trace elements zinc, manganese, copper, iron and boron. It has been accepted for many years that excesses of nutrients will lock up other nutrients (chart 1), so an excess of manganese will lock up your phosphorus and your potassium thereby affecting your root development and plant health. If you don’t test for manganese you would not be aware of this, and would then make incorrect decisions which may include the application of additional phosphorus, not realising that the reason for the poor root development is not a shortage of phosphorus but rather that it is locked up. The continued application of this phosphorus could then, if it continued, lock up calcium, magnesium, zinc, manganese, copper and iron. So, it is important to test all the nutrients that have a bearing on the other nutrients. When the results (chart 2) are returned
from the laboratory, I believe that the Turf Manager should receive a copy of the exact figures. Managing turf is a mix of art and science, and there is no target for any nutrient. On a sandy rootzone one turf manager may feel that a phosphorus level of sixteen is low, another could think it was high and a third may feel that it is ideal. For this reason you should see the figures and not just the fertiliser salesman’s opinion. With experience you can identify more and more from soil results and this can be massively helpful. We recently received soil test results from polo fields in The United
Arab Emirates. We were able to identify a very high risk of developing black layer on one of the fields and suggested further tests and a programme designed to flush the excess sulphur. The Turf Manager was delighted that we could identify a problem at distance, and he was able to cure the problem and achieved a remarkable improvement in the quality of his turf. Another figure on a soil report is cec, this is an abbreviation of cation exchange capacity and is a very good indicator of how much nutrient a soil will retain. Typically, a sandy soil will have a cec of four to six, with a high clay or organic soil having a cec of up to twenty, so the sandy soil will drain better but the clay soil, with a high organic content, will hold more nutrient.
One thing that is frequently misunderstood is that cec is not measured, it is in fact calculated, the calculation is:
- Calcium parts per million divided by 200 added to
- Magnesium parts per million divided by 120 added to
- Potassium parts per million divided by 390 added to
- Sodium parts per million divided by 240 This will give the cec.
The laboratory report should come back with a pre-calculated cec, but it is important that the Turf Manager understands that this has not been measured but rather calculated, and a heavy application of fertiliser prior to testing will make the cec appear artificially high.
I frequently get asked what is the ideal cec. The answer is that there is not an ideal level, just the one that you have. It is important to work with this rather than against it. If you have a low cec, there is no point in applying large amounts of nutrients in a single application. It is better to apply little and often, otherwise you will leach most of the nutrient, which is bad for both your budget and the environment. Having obtained the results, and decided which nutrients are in excess and which are in deficiency, it is then the task of the fertiliser supplier and the Turf Manager together to balance all the nutrients. The way I look at it is, an athlete is
strong and resists illness and injury but, when injured, recovers quickly; a big factor in this is that an athlete eats a balanced diet. Your turf should be able to fight off disease and recover quickly from damage however caused. To do this your plant needs a balanced diet. So, you should balance the nutrients in your rootzone. You cannot do this if you don’t know what is in the rootzone when you start.
Once you know your starting point you
can provide what is deficient and avoid what is in excess. Your nitrogen, phosphorus and potassium are the plants meat and two veg but, remember, that the plant needs all the other secondary and trace elements, just as the athlete needs his multi vitamins. Trust the doctor who cares enough to do the tests.
Author: Richard Lawrence Environmental Turf Technology Ltd. Tel: 01524 381999 Email:
ask@emailett.co.uk
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