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
2. Today’s schedule 09:25 – 11:25: all about 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. MLSN newsletter: www.subscribepage.com/mlsn ATC newsletter: www.subscribepage.com/atcupdate
6. The key concepts
7. Nutrient deficiencies are avoidable disasters.
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.
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)
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.
11. 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
12. 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
13. 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
14. 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
15. 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
16. MLSN is a method for soil test interpretation
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.
18. a, site-specific estimate of plant use
19. Growth = nutrient use
20. Not like this
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)
22. 3 ways to get a number for growth 1. Estimate from clippings.
23. 3 ways to get a number for growth 1. Estimate from clippings. 2. Estimate from N applied.
24. 3 ways to get a number for growth 1. Estimate from clippings. 2. Estimate from N applied. 3. Estimate from temperature.
25. b, amount to ensure remains in the soil
26. 1. The conventional way – low, medium, & high classification
27. 1. The conventional way – low, medium, & high classification 2. Conventional guidelines are broken
28. 1. The conventional way – low, medium, & high classification 2. Conventional guidelines are broken 3. The MLSN guidelines address these problems
29. The conventional way – low, medium, & high classification
30. The conventional way GCSAA GCM Magazine, January 2004
31. List of ranges • low • medium • high
32. “Low range: a high probability (80-100%) that applying the nutrient will elicit a growth response.”
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.”
34. “High range: little or no crop response is expected from applying the particular nutrient.”
35. Conventional guidelines are broken
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)
37. And grass is often grown in sand
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)
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)
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)
48. The MLSN guidelines address these problems
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)
50. The MLSN guidelines address these problems
51. c, the amount actually in the soil
52. Using MLSN
53. Let’s make sure we have enough beer
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
55. 3 common questions 1. MLSN is a target level, or minimum level?
56. 3 common questions 1. MLSN is a target level, or minimum level? 2. Same minimum for every grass, soil, and location? Customization?
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?
58. For more, please see www.asianturfgrass.com or @asianturfgrass on Twitter.