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MLSN & Turfgrass Nutrition

Micah Woods
November 22, 2019

MLSN & Turfgrass Nutrition

Micah Woods

November 22, 2019

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  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 2.

    We developed MLSN because … 3. Practical use of MLSN
  3. MLSN1 is a method for soil test interpretation. 1An initialism

    for minimum levels for sustainable nutrition.
  4. MLSN is designed to prevent nutrient deficiencies based on an

    analysis of the nutrients in the soil and the expected grass use of nutrients.
  5. Let’s have a look at soil test phosphorus (P) and

    potassium (K) for a 7 year sequence. First, the soil P …
  6. “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
  7. “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.
  8. “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
  9. “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.
  10. “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.
  11. “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
  12. “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.”
  13. “High range: little or no crop response is expected from

    applying the particular nutrient.”
  14. “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)
  15. “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)
  16. Reality: Conventional soil test calibration will never be done for

    even a fraction of the turf species, soil, and climate combinations.
  17. Two recent solutions 1. Fertiliser recommendations without soil test data.

    2. Fertiliser recommendations with soil test data.
  18. This is the STERF “Precision fertilisation” approach.6 6Ericsson, T., K.

    Blombäck and A. Kvalbein. 2013. Precision fertilisation—from theory to practice. STERF.
  19. “Precision fertilisation is based on the assumption that during vegetative

    growth …, grass requires nutrients in constant relative proportions.” Ericsson et al., 2013
  20. “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
  21. 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.
  22. 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
  23. 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.
  24. 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.
  25. 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
  26. 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.
  27. 3 ways to get a number for growth 1. Estimate

    from clippings. 2. Estimate from N applied.
  28. 3 ways to get a number for growth 1. Estimate

    from clippings. 2. Estimate from N applied. 3. Estimate from temperature.
  29. 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
  30. 3 common questions 1. MLSN is a target level, or

    minimum level? 2. Same minimum for every grass, soil, and location? Customization?
  31. 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?