Soil
WHAT YOU NEED TO KNOW NUTRIENTS
We can only produce good quality turf playing surfaces when we have the correct balance of chemical, biological and physical properties in the soil.
Of course we also need the right weather, the right machinery, and the right staff, but that is another story. For now I want to consider the balance of chemical nutrients in the soil, how they interact, and how they are used in the turf plant. An understanding of this helps us to avoid nutrient deficiencies, and is designed to promote the growth of strong, healthy, disease-free turf.
CATION EXCHANGE CAPACITY
Before we consider the individual nutrients, we ought to mention the soil's cation exchange capacity. The CEC is also known as the buffering capacity, it is a measure of the soil's ability to store nutrients. This measurement is the cornerstone of understanding soil analysis as it allows us to define target nutrient values for each particular soil.
Sands which have a low organic matter content have a low CEC, typically 1 to 4, while clay soils have a much higher CEC, normally in the range of 12 to 20. There is no perfect CEC, but often a high value is useful as it enables you to get better value for money from the fertiliser that you use. If the CEC values are low, the soil cannot hold onto applied nutrients, so useful management techniques would include the use of liquid feeds, controlled release fertilisers, or the use of regular light applications of fertiliser.
SOIL pH
The pH level of the soil is also of great importance as it affects the availability of the nutrients to the grass plant. Some agronomists would argue that the pH is best maintained at 7.0, as nutrients are most available at this level. However, fine turf grown at this high pH is more prone to worm disease and Poa problems.
Consequently, a lower pH of around 6.0 is thought to give the turf good access to nutrients whilst helping to control worm problems.
Many golf or bowling greens have a slightly lower pH, perhaps averaging 5.0, which means that they can be more prone to moss. Raising the pH of acidic greens can cause some difficulties, but does help to encourage more biological activity in the soil which then promotes thatch breakdown. The tendency towards a low soil pH can be alleviated by reducing the use of high sulphur / high iron fertilisers. Also, using a sand or topdressing of slightly higher pH (normally 6.5) will gradually raise the pH. The irrigation water should not be forgotten, as if it is of high pH and will gradually raise the soil pH over time.
NUTRIENT INTERACTIONS IN THE SOIL
It is important to understand that nutrients do not stand alone, but interact in the soil solution. These interactions affect the availability of each nutrient to the turf, and so we strive to keep them in optimum balance for healthy growth.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52