The (New) Fundamentals of Turfgrass Nutrition

Most seminars, presentations, articles, and even semester-long courses about turfgrass nutrition discuss the functions of different elements. Potassium is involved in stomatal regulation, phosphorus is essential for root development, calcium for cell wall strength, and so on. All true, but largely irrelevant for the turfgrass manager. What the turfgrass manager must know is not the function of each element, but the quantities -- is enough of this element present to meet the grass requirements, or is it not? If it isn't present in adequate quantities, how much must be added to ensure the grass has enough? In this seminar, the fundamentals of turfgrass nutrition will be explained, with a focus on an understanding of the amount of each nutrient that is required.

Transcript

1. The (New) Fundamentals of Turfgrass Nutrition Micah Woods Chief Scientist Asian Turfgrass Center www.asianturfgrass.com 13 January 2016 Northern Green Expo Minneapolis, Minnesota
2. What a ects growth? Growth is a function of photosynthetic light, plant water status, temperature, and a nutrient index.1 This can be represented as the environmental productivity index (EPI). 1Each of these factors can be represented by an index that takes a value from 0 to 1. Thus, the EPI will also have a value in the range of 0 to 1. The nutrient index is primarily a function of leaf N content.
3. What a ects growth? Growth is a function of photosynthetic light, plant water status, temperature, and a nutrient index.1 This can be represented as the environmental productivity index (EPI). (light)(water)(temperature)(nutrient) = EPI 1Each of these factors can be represented by an index that takes a value from 0 to 1. Thus, the EPI will also have a value in the range of 0 to 1. The nutrient index is primarily a function of leaf N content.
4. Light, Samui Island, Thailand
5. Light, Samui Island, Thailand
6. Light, Fukuoka, Japan
7. antum light meter
8. Water, Thailand
9. Temperature, Iceland
10. Nutrient – progressive K deficiency
11. Growth = nutrient use
12. Simplified EPI   XXX X (light)   XXX X (water)(temperature)(nutrient) = EPI
13. Law of the minimum? “In terms of Liebig’s Law of the Minimum, nitrogen is usually the element in shortest supply, and therefore applying nitrogenous fertilizers has a large impact on plant growth. The reason that nitrogen, of all the elements, is so o en limiting to growth is simply that plants require a great deal of it.” Jonathan Silvertown in Demons in Eden: The Paradox of Plant Diversity.
14. Not like this
15. What is important soil pH
16. What is important soil pH soil organic ma er content
17. What is important soil pH soil organic ma er content N application rate
18. What is important soil pH soil organic ma er content N application rate K in the soil
19. What is important soil pH soil organic ma er content N application rate K in the soil P in the soil
20. pH “In many parts of the world notably the US Midwest and Europe, soils have been limed to a particular target pH [6.5 to 7.0] according to the crop. Because plants do not directly respond to the activity of H+, it is pertinent to enquire why this approach to liming has enjoyed such widespread popularity ... Liming experiments throughout the world reveal that, with very few exceptions, all crops including legumes cease to respond to lime above pH [5.5 to 5.8]” Sumner and Yamada in Farming with Acidity, Communications in Soil Science and Plant Analysis, 2002.
23. pH, GSS summary 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 pH
24. OM%, GSS summary 0.0 2.5 5.0 7.5 10.0 OM360
25. K ppm, GSS summary 0 50 100 150 200 250 KM3
26. P ppm, GSS summary 0 100 200 300 400 PM3
27. What is important soil pH, know it, normal conditions are pH in the range of 5.5 to 8.3
28. What is important soil pH, know it, normal conditions are pH in the range of 5.5 to 8.3 soil organic ma er content, I like to know it
29. What is important soil pH, know it, normal conditions are pH in the range of 5.5 to 8.3 soil organic ma er content, I like to know it N application rate, know it, and adjust it to achieve the desired growth rate
30. What is important soil pH, know it, normal conditions are pH in the range of 5.5 to 8.3 soil organic ma er content, I like to know it N application rate, know it, and adjust it to achieve the desired growth rate K in the soil, keep above the MLSN guideline
31. What is important soil pH, know it, normal conditions are pH in the range of 5.5 to 8.3 soil organic ma er content, I like to know it N application rate, know it, and adjust it to achieve the desired growth rate K in the soil, keep above the MLSN guideline P in the soil, keep above the MLSN guideline
32. Two questions 1. Is this element required as fertilizer? 2. If it is required, how much should I apply?