MLSN & Turfgrass Nutrition

Transcript

1. MLSN & Turfgrass Nutrition Micah Woods November 26–29, 2019 Chief Scientist Asian Turfgrass Center www.asianturfgrass.com
2. Three key points today 1. Results when using MLSN
3. Three key points today 1. Results when using MLSN 2. We developed MLSN because …
4. Three key points today 1. Results when using MLSN 2. We developed MLSN because … 3. Practical use of MLSN
5. Results when using MLSN
6. MLSN1 is a method for soil test interpretation. 1An initialism for minimum levels for sustainable nutrition.
7. MLSN is designed to prevent nutrient deficiencies based on an analysis of the nutrients in the soil and the expected grass use of nutrients.
8. Nutrient deficiencies are avoidable disasters.
9. decreasing levels of soil K
10. ATC 南店
11. ATC 南店
12. ATC 南店
13. ATC 南店
14. ATC 南店
15. ATC 南店
16. Let’s have a look at soil test phosphorus (P) and potassium (K) for a 7 year sequence. First, the soil P …
19. Keya GC, Fukuoka
20. Keya GC, Fukuoka
21. Keya GC, Fukuoka
24. Keya GC, Fukuoka
25. Keya GC, Fukuoka
26. We developed MLSN because …
27. 48 years ago …
28. “Fertilizer is the number one management tool. It is worth all the attention you can give it.” Madison, 19712 2Madison, J.H. 1971. Principles of turfgrass culture. New York: Van Nostrand Reinhold Co. p. 270
29. 41 years ago …
30. “A study was conducted to determine differences among soil testing laboratories … in fertilizer recommendations for turfgrass maintenance and establishment.” Turner & Waddington, 19783 3Turner, T.R. and D.V. Waddington. 1978. Survery of soil testing programs for turfgrasses. Comm. Soil Sci. Plant Anal. 9(1):71-87.
31. “Unfortunately, turfgrass recommendations appear to be based on research done with other crops, such as forages, results from turfgrass fertility studies not designed to relate to soil testing, and the best judgement of the agronomist making the recommendations.” Turner & Waddington, 1978
32. Eighteen years ago …
33. “In some cases, turfgrasses have been placed in a ‘high’ P and K requirement category … This decision was based on economics, not agronomics. The cost of fertilization was not considered of primary importance for turf.” Carrow et al., 20014 4Carrow, R.N., Waddington, D.V., and P.E. Rieke. 2001. Turfgrass Soil Fertility and Chemical Problems. Wiley. p. 164.
34. Six years ago … Surely these issues have been resolved?
35. “Calibration of … soil P with turfgrass growth and subsequent P fertilization recommendations is scant, and additional data is needed. Many current recommendations for P fertilizer for turfgrasses are based on forage- or field-crop calibration data.” Frank & Guertal, 20135 5Frank, K.W. and E.A. Guertal. 2013. Potassium and phosphorus research in turfgrass. In: Stier, J.C., B.P. Horgan, and S.A. Bonos, editors, Turfgrass: Biology, Use, and Management, Agron. Monogr. 56. ASA, CSSA, SSSA, Madison, WI. p. 493-519.
36. “Relationships between extracted soil K, K fertilization rates, and turfgrass response needs additional study. Such work is especially missing for the sand-based systems in which many turfgrasses are managed.” Frank & Guertal, 2013
37. The conventional way – low, medium, & high classification
38. The conventional way GCSAA GCM Magazine, January 2004
39. List of ranges • low • medium • high
40. “Low range: a high probability (80-100%) that applying the nutrient will elicit a growth response.”
41. “Medium range: approximately a 50% chance of getting a plant growth response …; if supplemental fertilizer is not applied, growth will probably be limited, especially as the season progresses.”
42. “High range: little or no crop response is expected from applying the particular nutrient.”
43. “Every time a researcher conducts one of these studies, they tend to find that the levels required are lower than what we previously thought – meaning that ‘low potassium’ you got on your last soil test report might be optimum down the road.” Doug Soldat in “How reliable is soil testing?” (2013)
44. “I recommend you compare your results with PACE Turf’s Minimum Levels for Sustainable Nutrition [MLSN] guidelines ... the minimum levels published by PACE are drastically lower than many traditional soil test interpretations, and likely more accurate.” Doug Soldat in “How reliable is soil testing?” (2013)
45. The MLSN guidelines address these problems
46. Festuca, Iceland
47. Zoysia, Italy
48. Agrostis, Cynodon, and Festuca, Portugal
49. Poa annua, France
50. Reality: Conventional soil test calibration will never be done for even a fraction of the turf species, soil, and climate combinations.
51. Poa pratensis, Japan
52. Paspalum vaginatum, Thailand
53. Axonopus compressus, Indonesia
54. Digitaria didactyla, Sri Lanka
55. Two recent solutions 1. Fertiliser recommendations without soil test data.
56. Two recent solutions 1. Fertiliser recommendations without soil test data. 2. Fertiliser recommendations with soil test data.
57. Fertiliser recommendations without soil test data
58. In this case, it makes sense to apply—at least initially—all that the plant can use.
59. This is the STERF “Precision fertilisation” approach.6 6Ericsson, T., K. Blombäck and A. Kvalbein. 2013. Precision fertilisation—from theory to practice. STERF.
60. “Precision fertilisation is based on the assumption that during vegetative growth …, grass requires nutrients in constant relative proportions.” Ericsson et al., 2013
61. “By matching fertilisation to requirements during the season, it is possible to avoid undesirable fluctuations in grass growth and playing quality.” Ericsson et al. 2013
62. Fertiliser recommendations with soil test data
63. In this case, one wants to ensure the grass is supplied with all that it can use. If the soil can supply some—or all—of that amount, then the fertiliser recommendation accounts for the soil supply.
64. Minimum levels for sustainable nutrition (MLSN) • Joint project7 of ATC (me) & PACE Turf (Wendy Gelernter and Larry Stowell, California) • Started with 16,163 soil samples collected from good-performing turf • Selected a subset of 3,683 with: • pH ≥ 5.5 & ≤ 8.5 • CECsum ≤ 60 mmolc kg-1 7Woods M.S., L.J. Stowell, and W.D. Gelernter. 2016. Minimum soil nutrient guidelines for turfgrass developed from Mehlich 3 soil test results. PeerJ Preprints 4:e2144v1 https://doi.org/10.7287/peerj.preprints.2144v1
71. https://asianturfgrass.shinyapps.io/turfsi/
72. Practical use of MLSN
73. The two possible extremes 1. Supply nothing and assume the soil can provide all the grass requires. 2. Supply 100% (or more) of the nutrients the grass can use.8 8This approach makes the implicit assumption that the soil cannot supply the nutrients.
74. Two questions 1. Is this element required as fertilizer? 2. If it is required, how much should I apply? To answer those questions, we need to know how much is used by the grass and how much can be supplied by the soil.
75. T o a n s w e r t h o s e f u n d a me n t a l q u e s t i o n s , w e n e e d t o e s t i ma t e 3 q u a n t i t i e s c r e e p i n g b e n t g r a s s S h a n g h a i , C h i n a
76. a, b, and c • a is a site-specific estimate of plant use. • b is the amount we want to ensure remains in the soil after the plant use is accounted for. This is a minimum we don’t want to drop below. You can think of it as a reserve amount in the soil. This is the MLSN guideline level. • c is the amount actually present in the soil. This is the soil test result.
77. a, site-specific estimate of plant use
78. Growth = nutrient use
79. 3 ways to get a number for growth 1. Estimate from clippings.
80. 3 ways to get a number for growth 1. Estimate from clippings. 2. Estimate from N applied.
81. 3 ways to get a number for growth 1. Estimate from clippings. 2. Estimate from N applied. 3. Estimate from temperature.
82. b, amount to ensure remains in the soil
83. More specifically... One can express the quantity of an element required as fertilizer as Q. a + b − c = Q where, a is the quantity of the element used by the grass b is the quantity of the element kept in the soil c is the quantity of the element present in the soil Q is the quantity of the element required as fertilizer
86. 3 common questions 1. MLSN is a target level, or minimum level?
87. 3 common questions 1. MLSN is a target level, or minimum level? 2. Same minimum for every grass, soil, and location? Customization?
88. 3 common questions 1. MLSN is a target level, or minimum level? 2. Same minimum for every grass, soil, and location? Customization? 3. How do I know the nutrients are available?
90. www.asianturfgrass.com