Using and understanding the MLSN guidelines for nutrient recommendations

These guidelines are designed to prevent nutrient deficiencies based on an analysis of the nutrients in the soil and the expected grass use of nutrients. Since their introduction in 2012, the MLSN guidelines have come into use at turfgrass sites around the world. This workshop shares the latest information about the MLSN guidelines, including how to use them, why they have received so much attention, and points to pay careful attention to when implementing them.

Transcript

1. Using and understanding the MLSN
   guidelines for nutrient recommendations
   Micah Woods
   January 23, 2018
   Chief Scientist
   Asian Turfgrass Center
   www.asianturfgrass.com
   

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2. Today’s schedule
   09:25 – 11:25: all about MLSN
   

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3. MLSN1 is a method for soil test interpretation.
   1An initialism for minimum levels for sustainable nutrition.
   

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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.
   

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5. MLSN newsletter:
   www.subscribepage.com/mlsn
   ATC newsletter:
   www.subscribepage.com/atcupdate
   

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6. The key concepts
   

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7. Nutrient deficiencies are avoidable disasters.
   

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8. 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.2
   2This approach makes the implicit assumption that the soil cannot supply the nutrients.
   

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9. “How many more times do I have to say that applying
   nutrients to turfgrass growing on soil already well
   supplied with the nutrients is a waste of time and
   money?”
   Wayne Kussow in “Manipulating Creeping Bentgrass Nutrition”
   (1995)
   

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10. 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.
    

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16. MLSN is a method for soil test
    interpretation
    

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17. 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.
    

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18. a, site-specific estimate of plant
    use
    

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19. Growth = nutrient use
    

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20. Not like this
    

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21. 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 often limiting to growth is simply that
    plants require a great deal of it.”
    Jonathan Silvertown in Demons in Eden: The Paradox of Plant
    Diversity (2005)
    

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22. 3 ways to get a number for growth
    1. Estimate from clippings.
    

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23. 3 ways to get a number for growth
    1. Estimate from clippings.
    2. Estimate from N applied.
    

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24. 3 ways to get a number for growth
    1. Estimate from clippings.
    2. Estimate from N applied.
    3. Estimate from temperature.
    

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25. b, amount to ensure remains in
    the soil
    

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26. 1. The conventional way – low, medium, & high classification
    

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27. 1. The conventional way – low, medium, & high classification
    2. Conventional guidelines are broken
    

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28. 1. The conventional way – low, medium, & high classification
    2. Conventional guidelines are broken
    3. The MLSN guidelines address these problems
    

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29. The conventional way – low,
    medium, & high classification
    

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30. The conventional way
    GCSAA GCM Magazine, January 2004
    

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31. List of ranges
    • low
    • medium
    • high
    

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32. “Low range: a high probability (80-100%)
    that applying the nutrient will elicit a
    growth response.”
    

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33. “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.”
    

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34. “High range: little or no crop response is
    expected from applying the particular
    nutrient.”
    

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35. Conventional guidelines are
    broken
    

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36. “In some cases, turfgrasses have been placed in a
    ‘high’ P and K requirement category, while pasture
    grasses were in a ‘low’ category. This decision was
    based on economics, not agronomics. The cost of
    fertilization was not considered of primary
    importance for turf.”
    Carrow, Waddington, and Rieke in Turfgrass Soil Fertility and
    Chemical Problems (2001)
    

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37. And grass is often grown in sand
    

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38. “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 in “Survey of soil testing programs for
    turfgrasses” (1978)
    

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39. “Numerous turfgrass fertility studies … either did not
    take into account intitial soil fertility levels, or were
    conducted on only one level of initial fertility.”
    Turner & Waddington in “Survey of soil testing programs for
    turfgrasses” (1978)
    

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47. “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)
    

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48. The MLSN guidelines address
    these problems
    

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49. “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)
    

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50. The MLSN guidelines address these problems
    

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51. c, the amount actually in the soil
    

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52. Using MLSN
    

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53. Let’s make sure we have enough beer
    

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54. 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
    

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55. 3 common questions
    1. MLSN is a target level, or minimum level?
    

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56. 3 common questions
    1. MLSN is a target level, or minimum level?
    2. Same minimum for every grass, soil, and location?
    Customization?
    

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57. 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?
    

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58. For more, please see
    www.asianturfgrass.com or
    @asianturfgrass on Twitter.
    

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