This document presents a modern method for estimating turfgrass nutrient requirements using Minimum Levels for Sustainable Nutrition (MLSN) guidelines. The MLSN guidelines provide soil nutrient levels that 10% of well-performing turfgrass soils fall below. To determine fertilizer needs, the method calculates the amount of an element the grass will use (harvest), the amount needed to remain in the soil per the MLSN, and the current soil levels, with fertilizer making up the difference. Examples are provided to demonstrate calculating potassium and calcium needs using the MLSN method.

1. A Modern Method for
Estimating Turfgrass Nutrient
Requirements
Micah Woods, Ph.D.
Chief Scientist | Asian Turfgrass Center
7 October 2014
Idaho GCSA Fall Meeting
Pinecrest Golf Course, Idaho Falls
seminar.asianturfgrass.com/2014_igcsa.html

2. We need to know 3
quantities
L-93 creeping bentgrass
Ithaca, New York
1. How much of
an element is
present in the soil?
2. How much of
an element is
needed in the soil?
3. How much of
an element does
the grass use?

3. As the grass grows, and as it is
mowed, nutrients are removed Kyushu, Japan

4. Element C3 grass
N 4%
K 2%
P 0.5%
Ca 0.5%
Mg 0.2%
S 0.2%
Macro and secondary nutrient content in grass leaves

9. http://www.paceturf.org/journal/
new_and_improved_climate_appraisal_form

10. bent & Poa annua may use 0.6 lbs
N/1000 ft2/month in good weather Oregon, USA

13. 2.8
1.4
0.35 0.35
0.14 0.14
4
3
2
1
0
N K P Ca Mg S
Element
Predicted Use per 1000 (ft2)

14. January GCM: www.gcsaa.org

15. We need to know 3
quantities
L-93 creeping bentgrass
Ithaca, New York
1. How much of
an element is
present in the soil?
2. How much of
an element is
needed in the soil?
3. How much of
an element does
the grass use?

16. Reference
September, 2014
Minimum Levels for Sustainable Nutrition
Soil Guidelines
The Minimum Level for Sustainable Nutrition (MLSN) Guideline is a new, more sustainable ap-proach
to managing soil nutrient levels that can help you to decrease fertilizer inputs and costs,
while still maintaining desired turf quality and playability levels. The MLSN guidelines were devel-oped
in a joint project between PACE Turf and the Asian Turfgrass Center. All soil analyses were
conducted at Brookside Laboratories, New Bremen, OH.
MLSN Soil
Guideline
pH >5.5
Potassium (K ppm) 37
Phosphorus (P ppm) 21
Calcium (Ca ppm) 331
Magnesium (Mg ppm) 47
Sulfur as sulfate (S ppm) 7
Nitrogen requirements are best determined based on turf growth potential, which incorporates
VLWHVSHFLoFZHDWKHUDQGWXUIWSHWRFDOFXODWHQLWURJHQGHPDQG*HOHUQWHUDQG6WRZHOO*ROI
Course Management, p. 108-113, March, 2005).

17. http://www.paceturf.org/journal/global_soil_survey

18. The amount of fertilizer to apply is:
The amount we need
minus
The amount we have

19. The amount we need is:
the amount the grass will use (harvest)
plus
the amount we need to retain in the soil (MLSN)

20. The amount we have is:
the amount in the soil (soil test result)

21. Expressed as an equation, the amount of fertilizer
(F) to apply is:
MLSN (lbs/1000 ft2) + Harvest (lbs/1000 ft2)
- soil test (lbs/1000 ft2) = F

22. Reference
Minimum Levels for Sustainable Nutrition
Soil Guidelines
The Minimum Level for Sustainable Nutrition (MLSN) Guideline is a new, more sustainable ap-proach
to managing soil nutrient levels that can help you to decrease fertilizer inputs and costs,
while still maintaining desired turf quality and playability levels. The MLSN guidelines were devel-oped
in a joint project between PACE Turf and the Asian Turfgrass Center. All soil analyses were
conducted at Brookside Laboratories, New Bremen, OH.
Nitrogen requirements are best determined based on turf growth potential, which incorporates
VLWHVSHFLoFZHDWKHUDQGWXUIWSHWRFDOFXODWHQLWURJHQGHPDQG*HOHUQWHUDQG6WRZHOO*ROI
Course Management, p. 108-113, March, 2005).
How the guidelines were developed
)URPDGDWDEDVHRIRYHUVRLOVDPSOHVZHVHOHFWHGWKDWZHUHFODVVLoHGDVKDYLQJ
v not poor performing turfgrass
v pH 5.5 - 8.5 to avoid aluminum toxicity
v total exchange capacity 6 cmol/kg
$ORJORJLVWLFPRGHOSURYLGHGDVLJQLoFDQWoWRIWKHGDWDDQGZDVXVHGWRLGHQWLIWKHFRQFHQWUD-
tion (in ppm) of each nutrient that 10% of the soil samples fell below, but were still performing well.
This 10th percentile value is the MLSN soil guideline shown above.
For more information, see the Facebook MLSN page at: www.facebook.com/mlsnturf
©2014 PACE Turf, LLC 1267 Diamond Street, San Diego CA 92109 www.paceturf.org
version 14091801
September, 2014
MLSN Soil
Guideline
pH 5.5
Potassium (K ppm) 37
Phosphorus (P ppm) 21
Calcium (Ca ppm) 331
Magnesium (Mg ppm) 47
Sulfur as sulfate (S ppm) 7
How to convert between ppm and lbs/1000 ft2?

23. Adding an element as fertilizer:
1 lb/1000 ft2 will increase the top 4 inches by 34 ppm
0.1 lb/1000 ft2 will increase the top 4 inches by 3.4 ppm

24. As the plant harvests elements:
1 lb/1000 ft2 will decrease the top 4 inches by 34 ppm
0.1 lb/1000 ft2 will decrease the top 4 inches by 3.4 ppm

25. MLSN (lbs/1000 ft2) + Harvest (lbs/1000 ft2)
- soil test (lbs/1000 ft2) = F

26. let’s say we harvest 1.4 lbs K and
soil test K is 50 ppm

27. MLSN (37 ppm) + 1.4 lbs/1000 ft2
- soil test (50 ppm) = F

28. 1.1 lbs/1000 ft2 + 1.4 lbs/1000 ft2
- 1.5 lbs/1000 ft2 = F

29. 1.1 lbs/1000 ft2 + 1.4 lbs/1000 ft2
- 1.5 lbs/1000 ft2 = 1 lbs/1000 ft2

30. #$

31. !

32. 1.5
−1.4 0
0.093
1.5
1.0
0.5
0.0
Soil Test Annual
Plant Uptake
Fertilizer
Applied
Remaining
in Soil
K, lbs per 1000 (ft2)

33. #$

34. !

35. 1.5
−1.4 1
1.1
1.5
1.0
0.5
0.0
Soil Test Annual
Plant Uptake
Fertilizer
Applied
Remaining
in Soil
K, lbs per 1000 (ft2)

36. 15
−0.35 0
15
15
10
5
0
Soil Test Annual
Plant Uptake
Fertilizer
Applied
Remaining
in Soil
Ca, lbs per 1000 (ft2)

37. 2.8
1.4
0.35 0.35
0.14 0.14
4
3
2
1
0
N K P Ca Mg S
Element
Predicted Use per 1000 (ft2)
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