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See the presentation handout here (http://seminar.asianturfgrass.com/2014_hgcsa.html) with links to files and websites mentioned in the presentation. As a subtitle to this presentation, I used "why K fertilizer is almost always required but Ca is not, and the controlling role of N, among other examples to illustrate the point." The quick reason why that subtitle is important to understand is this. Adding more nitrogen (N) makes the grass grow more, which naturally increases the demand of all other nutrients. That makes sense, because as the plant grows more, it produces more leaves and stems and roots -- it is a bigger plant. And when there is a bigger plant, in order to maintain nutrient levels in the plant, more of every nutrient will be required. But why is potassium (K) almost always required as fertilizer, but calcium (Ca) is not? That is because grass in Hawaii, over the course of about a year, will use more K than is available in the soil. So if K is not added as fertilizer, the soil K will get so low that plant uptake of K may be too low. With Ca, that isn't the case. The amount of Ca in the soil is large, and the amount used by the grass is less, so even over a span of multiple years, the grass can obtain all the calcium it will use from the soil. The presentation explains how this can be calculated.
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The secret to preventing nutrient deficiencies: why K fertilizer is almost always required but Ca is not, and the controlling role of N, among other examples to illustrate the pointMicah Woods, Ph.D.Chief Scientist | Asian Turfgrass Center3 October 2014Hawaii GCSA Annual SeminarPrince Hotel Waikikiseminar.asianturfgrass.com/2014_hgcsa.html
2 questions
1. Do we need to add fertilizer?
2. How much do we need to add?
When we mow grass, nutrients are removed from the plant Fukuoka, Japan
Can we estimate how much of each nutrient is used?
Oahu
bermudagrass may use 0.8 lbs N/1000 ft2/month in good weather Oahu
seashore paspalum may use 0.6 lbs N/1000 ft2/month in good weather Lanai
http://www.paceturf.org/journal/new_and_improved_climate_appraisal_form
bermudagrass in low temperatures
New Delhi, India, late December
bermudagrass in hot temperatures
New Delhi, India, March
I expect paspalum to use less N than bermuda
Oahu
bermuda and seashore paspalum
ATC Research Facility, Thailand
bermuda and seashore paspalum
Bangkok, Thailand
Element Bermuda Paspalum
N 3% 3%
K 2% 3%
P 0.5% 0.5%
Ca 0.5% 0.5%
Mg 0.2% 0.2%
S 0.2% 0.2%
Macro and secondary nutrient content in grass leaves
bermudagrass, how many nutrients does it use?
Oahu
bermuda
6.7
4.5
1.1 1.10.45 0.45
0
2
4
6
8
N K P Ca Mg SElement
Pred
icte
d U
se p
er 1
000 (ft
2 ) bermuda
paspalum, how many nutrients does it use?
Oahu
paspalum
5 5
0.84 0.840.33 0.33
0
2
4
6
8
N K P Ca Mg SElement
Pred
icte
d U
se p
er 1
000 (ft
2 ) paspalum
Most of the roots are in the top 4 inches of the soil Hanoi, Vietnam
Reference
©2014 PACE Turf, LLC 1267 Diamond Street, San Diego CA 92109 www.paceturf.org
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.
How the guidelines were developed
not poor performing turfgrasspH 5.5 - 8.5 to avoid aluminum toxicitytotal exchange capacity <6 cmol/kg
-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
version 14091801
Nitrogen requirements are best determined based on turf growth potential, which incorporates
Course Management, p. 108-113, March, 2005).
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?
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
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
6.7
4.5
1.1 1.10.45 0.45
0
2
4
6
8
N K P Ca Mg SElement
Pred
icte
d U
se p
er 1
000 (ft
2 ) bermuda
ReferenceMinimum 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
Course Management, p. 108-113, March, 2005).
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
http://www.paceturf.org/journal/global_soil_survey
The amount of fertilizer to apply is:
The amount we need
minus
The amount we have
The amount we need is:
the amount the grass will use (harvest)
plus
the amount we need to retain in the soil (MLSN)
The amount we have is:
the amount in the soil (soil test result)
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
let’s say we harvest 4.5 lbs K and soil test K is 50 ppm
Oahu
MLSN (lbs/1000 ft2) + Harvest (lbs/1000 ft2)
- soil test (lbs/1000 ft2) = F
MLSN (37 ppm) + 4.5 lbs/1000 ft2
- soil test (50 ppm) = F
1.1 lbs/1000 ft2 + 4.5 lbs/1000 ft2
- 1.5 lbs/1000 ft2 = F
1.1 lbs/1000 ft2 + 4.5 lbs/1000 ft2
- 1.5 lbs/1000 ft2 = 4.1 lbs/1000 ft2
1.5
−4.5 0 −3−3
−2
−1
0
1
Soil Test AnnualPlant Uptake
FertilizerApplied
Remainingin Soil
K, lb
s pe
r 100
0 (ft
2 )
1.5
−4.5 4.1
1.1
−3
−2
−1
0
1
Soil Test AnnualPlant Uptake
FertilizerApplied
Remainingin Soil
K, lb
s pe
r 100
0 (ft
2 )
15
−1.1 0
140
5
10
15
Soil Test AnnualPlant Uptake
FertilizerApplied
Remainingin Soil
Ca,
lbs
per 1
000 (ft
2 )
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