FE ATURE ◗ AGNAR KVALBEIN & TRYGVE S. AAMLID
Green Fertilization The Scandinavian Way ◗ Although Norway is a small country, it stretches out from the latitude 58 to 71˚ north. This makes light conditions comparable to those in the northern half of the Canadian mainland. The climate is mild due to the north Atlantic drift which keeps the country inhabitable and the coast free from ice throughout the winter. The annual precipitation ranges from more than 2000 mm on the west coast to less than 200 mm in the valleys sheltered from the dominating western winds. The fertilization practices on the 170 Norwegian golf courses have, for the last years, been influenced by associate professor Tom Ericsson from the Agricultural University of Sweden. He was a member of Professor Torsten Ingestad’s research group that worked on plant nutrition for some decades. Their work had great influence on fertilization practises in the forest industry, greenhouse production and nurseries. Sand-based golf greens are in many ways comparable to the inactive growth media used in greenhouses and the fertilization techniques that gardeners use to control plant growth and quality can be transferred to golf. For some years, we have based the fertilization on our experimental greens at the Bioforsk Turfgrass Research Centre on these theories and this article is therefore based both on our practical experiences and on results from completed and ongoing research. Most of the projects have been funded by the Scandinavian Turfgrass and Environment Research Foundation.
Basic Principles in Short
1. T he fertility rate should be adapted to the grass species’ genetic growth capacity. 2. F ertilizer should be applied as a complete, balanced mix of nutrients where nitrogen is the minimum factor. The same nutrient solution can be used year-round. 3. F ertilizers should be applied frequently at low rates (preferably weekly spoon-feeding). The application plan should be set up
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3. Colonial bent grass (Agrostis capillaris L.) (syn. Agrostis tenuis Sibth.) 4. Slender creeping red fescue (Festuca rubra var litoralis) (syn. F.rubra var thichophylla) 5. Chewing fescue (Festuca rubra var commutata)
The Balanced Fertilizer
FIGURE 1. NORMAL ANNUAL TEMPERATURE IN NORWAY. PHOTO CREDIT: WWW.MET.NO
according to the main external growth factors, i.e. light and temperature (We assume that the greenkeeper controls water, soil oxygen and other limiting factors). 4. Extending the period with fertilizer inputs in autumn does not impair winter survival, but improves spring performance of the turf.
Grass Species’ Growth Capacity / Fertilizer Demand
Based on a greenhouse study and a two-year field experiment (Ericsson et al. 2012 a,b), the grass species for greens were ranked in the following way according to decreasing growth capacity and thus demand for fertilizers: 1. A nnual meadow grass (Poa annua L.) 2. C reeping bent grass (Agrostis stolonifera L.)
In the experiments, we used a mixture of nutrients which has proved to be correct for all plants under normal, slightly acid soil conditions (Knecht & Göransson 2004). This basic recipe offers a very good starting point for all fertilization plans. Table 1 shows only the nutrients which normally have to be applied under Scandinavian conditions. It is important that nutrients which are directly involved in photosynthesis, i.e. potassium, magnesium, iron and manganese, never become minimum factors in the mixture (Ericsson 1995). We recognize that an enhanced level of some elements, like sulfur or iron, may be beneficial for other reasons than plant growth and that several non-nutrient elements such as silicon (Si) and organic molecules may provide additional strength to the plant under stressful conditions. However, this article focuses on basic fertilization.
Table 1:
A balanced fertilizer, expressed as relative amounts of elements in proportion to nitrogen(=100) Nitrogen
N
100
Potassium
K
80
Phosphorus
P
12
Magnesium
Mg
8
Sulfur
S
8
Calcium
Ca
6
Iron
Fe
0.7
Boron
B
0.2
Manganese
Mn
0.4
Zinc
Zn
0.06