PRECISION FERTILISATION – FROM THEORY TO PRACTICE The authors of this fertilisation manual. From left: Tom Ericsson, Karin Blombäck and Agnar Kvalbein. ABOUT THE MANUAL FIND OUT MORE This manual summarises the knowledge and Demand-driven fertilization. Part I: Nitrogen pro- experiences gained in three research projects on precision ductivity in four high-maintenance turf grass spe- fertilisation funded by STERF in the period 2003-2011: cies. T. Ericsson, K. Blombäck & A. Neumann 2012. - Acta Agriculturae Scandinavica, 62(1):113-121. • Effect of precision fertilisation on the growth, appearance and nitrogen utilisation of turfgrasses Demand-driven fertilization. Part II: Influence of demand-driven fertilization on shoot nitrogen con- • Fertiliser strategies for golf turf: Implications for centration, growth rate, fructan storage and playing physiology-driven fertilisation quality of golf turf. T. Ericsson, K. Blombäck & A. Neu- mann 2012. - Acta Agriculturae Scandinavica, 62(1):139-149. • Impact of mowing height and late autumn fertilisa- tion on winter survival of golf greens in the Nordic Green fertilization the Scandinavian way. A. Kvalbein countries & T. S. Aamlid 2012. http://sterf.golf.se Information about these projects and popular science and Precision fertilisation – Resultaten from Fulleröför- scientific papers can be found atsterf.golf.se söket 2003 – 2004. T. Ericsson, J. Orsholm & A. Hedlund. http://sterf.golf.se Precision fertilisation – from theory till practice. A. Hedlund. http://sterf.golf.se Impact of mowing height and late autumn fertiliza- tion on winter survival and spring performance of golf greens in the Nordic countries. 2011. A. Kvalbein & T. S. Aamlid. http://sterf.golf.se NEW TIMES DEMAND NEW APPROACHES Long before the beginning of the modern age, it was grass and knowledge of how these requirements vary known that all plants need some form of nutrients during the season. This is the underlying reasoning for in order to grow and develop in a satisfactory way. the concept ‘precision fertilisation’. However, it was only discovered in the mid-1800s that the ‘food’ used by plants consists primarily of basic Precision fertilisation is based on the assumption that elements from the Earth’s crust. Today, we know that during vegetative growth (i.e. in the absence of stem all plants require the same 14 elements and we have elongation and flowering), grass requires nutrients in good knowledge of why these elements are required. constant relative proportions. The same fertiliser can Supplying nutrients has now become the most effecti- therefore be used from spring until autumn and ferti- ve measure for controlling the growth and influencing lisation can be adapted based on the nitrogen require- the quality of crops, including golf turf. The underly- ment of the grass. ing theory and the methods used for applying fertiliser to fairways and greens are strongly influenced by the Through precision fertilisation, the nitrogen content methods used in agriculture. However modern golf of the grass and therefore growth and quality charac- courses, particularly in terms of green constructions, teristics are determined by the genetic composition of differ from the soils in which arable crops are grown. the grass and the climate conditions found at the site. Greens built according to USGA norms have a very By matching fertilisation to requirements during the restricted nutrient storage capacity. Fertilisation in ex- season, it is possible to avoid undesirable fluctuations cess is therefore a method that should be avoided from in grass growth and playing quality. both an economic and environmental perspective. Instead, fertilisation of greens should be based around This manual presents the theory behind this fertilisa- small, frequently occurring doses, the size of which is tion concept, together with simple instructions on how determined by the actual nutrient requirements of the to carry out precision fertilisation. 3 4 Availability/amount Light Heat Potential growth and nutrient requirements Spring Summer Autumn Figure 1 - Seasonal dynamics – light, heat and potential growth/nutrient requirement of turfgrass. LIGHT AND HEAT CONTROL THE GROWTH POTENTIAL OF GRASS It is becoming increasingly common for nutrients to the plant and converted into carbohydrates via pho- be applied to greens in weekly doses, but the shape tosynthesis. These carbohydrates provide fuel for the of the fertilisation curve during the growing season plant and building materials for new shoots and roots. can vary widely between golf courses. There are many Growth, and the associated fertiliser requirement, are possible explanations for this variation, but the factors therefore greatest when the days are longest (Figure 1). determining the potential growth of grass, and there- fore its nutrient requirements, are the availability of It is not possible to force growth in the spring with the light, heat and water. Water availability is the only one help of large doses of nutrients when the machinery of these factors that can be easily controlled and influ- of the grass is operating in a low gear due to lack of enced, with the help of irrigation. Water availability is heat. Likewise, it is not possible to compensate for lack critically important for the ability of the grass to cool of light with increasing doses of nutrients as the days its leaves by transpiration on hot summer days. Good become shorter in autumn. access to water is also vital for cell division and elonga- tion, and thereby leaf growth, which is fundamental for the ability of the grass to capture solar energy and Warm summer days lower carry out photosynthesis. the nutrient requirement Day length and light intensity determine the amount It is not only low temperatures that inhibit grass of solar energy available to the grass for use in all the growth. As the temperature approaches 30 °C, the ef- energy-demanding processes involved in photosyn- ficiency of photosynthesis is reduced in plants adapted thesis. The temperature controls the rate of all bio- to the Nordic climate. This means that the growth- chemical processes and thus how rapidly new leaves determining role of light decreases in warm weather. and roots are formed during the season. In spring, it When photosynthesis is slower, there is a decrease is generally the temperature that restricts grass de- in the growth capacity of grass and thus also in its velopment, while in autumn it is lack of light that nutrient requirement. The fertiliser level may therefore causes growth to decline and thus also the nutrient need to be lowered in the middle of summer if a hot requirement (Figure 1). Therefore the availability of spell continues for more than a week, instead of conti- light together with the number of leaves determines nuing at maximum level when the days are longest. the amount of solar energy that can be captured by 5 cm Playing quality with increasing fertilisation Growth 140 120 ”Luxury uptake” 100 Sufficiency Toxicity Ball roll cm with 80 short stimpmeter Ballrull cm med kort stimpmeter 60 Hårdhet G-kraft Deficiency Hardness, g-faktor (1g = 9.80665m/s2 ) 40 20 Fertilisation intensity as a Leaf nitrogen concentration 0 percentage of maximum 40% 60% 100% requirement Figure 2 – Relationship between leaf nitrogen concentration Figure 5 – Effect of increasing fertilisation on playing quality. and growth.. Mean of six species in fertiliser trials at Landvik 2009. Biomass distribution between leaf and root Carbohydrate reserves High Leaves Low Roots Leaf nitrogen concentration Leaf nitrogen concentration Figure 3 – Effect of leaf nitrogen concentration on leaf and Figure 6 – Effect of leaf nitrogen concentration on the amount root development. of carbohydrate reserves. September 6 c) Leaf area per gram of leaf 5 4 Broad, thin leaves 3 2 % fructan in biomass fructanin % 1 0 Narrow, stiff leaves ’Center’ ’Cezanne’ ’Barking’ ’Legendary’ ’Independence’ White = 40% of max. requirement Leaf nitrogen concentration Grey = 60% of max. requirement Black = 100% of max. requirement Figure 4 – Effect of leaf nitrogen concentration on leaf Figure 7 – Effect of fertilisation intensity on carbohydrate formation. storage in the leaves of creeping bent. 6 Nitrogen is important for growth. This picture shows how the nitrogen content in the leaves affected shoot growth in uncut 40-day-old creeping bent plants in a climate chamber. Photo: Tom Ericsson NITROGEN CONTENT IN LEAVES CONTROLS MANY IMPORTANT PROCESSES Nitrogen is the nutrient that grass plants require most. amount of carbohydrates required to form a certain It is a component of amino acids and proteins, and leaf area is lower when access to nitrogen is good. therefore of enzymes, the compounds that control all the chemical reactions in the plant. Nitrogen is also an Fertilisation intensity also affects the capacity of the important component of plant DNA and hormones, grass to store carbohydrates in shoots and roots. As thereby playing a central role in the plant’s ‘machinery’. the amount of nitrogen available to the grass increases, It is a well-known fact that supplying nitrogen has a a greater proportion of the carbohydrates formed is powerful impact on plant growth (Figure 2). However, used for growth and thus a lower proportion is avai- nitrogen supply also affects a range of other important lable for storage in tissues and for use in other vital functions and characteristics. function (Figures 6 and 7). This in turn reduces the capacity of the grass to manufacture defence com-