mehlich 3 evaluation

Mehlich 3 EvaluationMehlich 3 Evaluation

Robert O. MillerALP Technical Director

Colorado State University

Fort Collins, CO

SERA-6 Meeting, Raleigh, NC, June 21, 2011SERA-6 Meeting, Raleigh, NC, June 21, 2011

Miller, 2011

ObservationsObservations

Miller, 2011

M3 Phosphorus observations across proficiency programs M3 Phosphorus observations across proficiency programs have shown consistent differences between ICP and SPEC P have shown consistent differences between ICP and SPEC P analysis methods on specific soils.analysis methods on specific soils.

Although a majority of soil testing labs utilize ICP for M3 P Although a majority of soil testing labs utilize ICP for M3 P analysis, many use nutrient calibration models based on SPEC analysis, many use nutrient calibration models based on SPEC analysis. analysis.

M3 SPEC – ICP differences have been report to be insignificant M3 SPEC – ICP differences have been report to be insignificant and a nonissue, however differences remain relevant.and a nonissue, however differences remain relevant.

M-3 Comparison M-3 Comparison

Miller, 2011

Proficiency program M-3 P comparisons SPEC vs ICPProficiency program M-3 P comparisons SPEC vs ICP

Correlative soils properties with M-3 P DifferencesCorrelative soils properties with M-3 P Differences

M-3 Solution Instrument Calibration, P and KM-3 Solution Instrument Calibration, P and K

M3 P Spec and ICP Comparisons

Miller, 2011

M3 P methods comparison of M3 P methods comparison of proficiency data proficiency data (NAPT) (NAPT) have have suggested method bias difference, suggested method bias difference, however the database lacks intra-however the database lacks intra-lab measurement error.lab measurement error.

M3 soil data from the M3 soil data from the ALPALP Program, Program, with intra-lab error , provides with intra-lab error , provides conclusive evidence P analysis conclusive evidence P analysis method differences, which are soil method differences, which are soil dependent.dependent.

Of 70 ALP soils, 32 indicate a Of 70 ALP soils, 32 indicate a statistical significant difference statistical significant difference between SPEC and ICP P values. between SPEC and ICP P values.

SRS-0702SRS-0702 * 38.338.3 1.21.2 39.739.7 2.8

SRS-0703 SRS-0703 **

20.720.7 1.21.2 40.440.4 2.6

SRS-0705SRS-0705 * 7.77.7 0.60.6 10.210.2 0.9

SRS-0715 SRS-0715 ** 20.620.6 1.21.2 45.545.5 3.2

SRS-0804 SRS-0804 ** 13.113.1 0.70.7 22.722.7 1.1

SRS-0901SRS-0901 * 102102 3.33.3 110110 4.1

SRS-0906 SRS-0906 ** 59.359.3 2.12.1 73.373.3 2.2

Soil IDSoil ID M3-P M3-P SpecSpec M3-P M3-P ICPICP

MeanMean StdevStdev MeanMean StdevStdev

M3 P methods significant different at the 0.05 level, three replications M3 P methods significant different at the 0.05 level, three replications multiple labsmultiple labs

Miller, 2011

Mehlich 3 P Spec vs ICPMehlich 3 P Spec vs ICP

1:1 line

70 Soils, Collected fromThirty States - ALP

ALP Data base 2006-2011ALP Data base 2006-2011

y = 1.15xy = 1.15xRR22 = 0.957 = 0.957

Mehlich 3 P Spec vs ICP Relative % DifferenceMehlich 3 P Spec vs ICP Relative % Difference

M3-P M3-P Range Range (ppm)(ppm)

0-100-10 10-2010-20 20-4020-40 40-6040-60 > 60> 60

% Diff.% Diff. 48.948.9 54.354.3 30.030.0 17.817.8 14.914.9

Miller, 2011

70 Soils, Collected from

Thirty States - ALP


Mehlich 3 P Spec vs ICPMehlich 3 P Spec vs ICPParse soil pH < 7.3 (0.01 M CaCl2), N = 50

1:1 line1:1 line

Miller, 2011


Mehlich 3 P Spec vs ICP Relative % DifferenceMehlich 3 P Spec vs ICP Relative % Difference

Miller, 2011

Reduced Data Set, pH < 7.3 (0.01 M CaCl2)

50 Soils, pH < 7.3pH < 7.3


Mehlich 3 P Spec vs ICP Delta CorrelationMehlich 3 P Spec vs ICP Delta Correlation

PropertyProperty11 CorrelationCorrelation

pH pH spsp - 0.419- 0.419

pH (1:1)pH (1:1) - 0.414- 0.414

M3-K M3-K - 0.321- 0.321

SOM-WBSOM-WB + 0.122+ 0.122

Sand %Sand % + 0.446+ 0.446

Silt %Silt % - 0.481- 0.481

Clay %Clay % - 0.3220.322

Miller, 2011

11 Correlations, soil pH < 7.3, phosphorus Correlations, soil pH < 7.3, phosphorus methods removed.methods removed.

28 soils28 soils


Reduced Data Set, pH < 7.3 (0.01 M CaCl2)

Mehlich P ICP-Colorimetric Difference vs Soil pH

-10

-5

0

5

10

15

20

5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4

Soil pH

Meh

lich

P C

olo

r -

ICP

Dif

fere

nce

(p

pm

)

Eliason, Lamb and Rehm, 2001 460 Soils - MN

M3 P Spec and ICP Comparisons

Miller, 2011

Differences in M-3 between SPEC and ICP can be Differences in M-3 between SPEC and ICP can be described as described as NNon-on-ReReactive active PPhosphoroushosphorous (NRP).(NRP).

Large NRP differences primarily associated with M3 Large NRP differences primarily associated with M3 P levels less than 40 ppm.P levels less than 40 ppm.

High NRP is identified with soils with low pH, high High NRP is identified with soils with low pH, high sand content and low silt contents. Maybe sand content and low silt contents. Maybe associated with aluminum. associated with aluminum.

Soils with high NRP were collected from Soils with high NRP were collected from Oklahoma, Arkansas, Iowa, eastern Nebraska and Oklahoma, Arkansas, Iowa, eastern Nebraska and eastern Illinois. No-Till soils greater difference.eastern Illinois. No-Till soils greater difference.

Mehlich 3 Standard Solution EvaluationMehlich 3 Standard Solution Evaluation

IDID11 P P (ppm)(ppm) K K (ppm)(ppm)

Bottle #1Bottle #1 8.28.2 154154

Bottle #2Bottle #2 19.619.6 86.586.5

Bottle #3Bottle #3 41.641.6 55.255.2

Bottle #4Bottle #4 96.696.6 451451

Bottle #5Bottle #5 00 00

Bottle #6Bottle #6 ?? ??

Bottle #7Bottle #7 ?? ??

An evaluation of seven M3 An evaluation of seven M3 solutions was conducted in 2010 solutions was conducted in 2010 of 24 labs. Seven bottles were of 24 labs. Seven bottles were prepared, #1- #5 from reagent prepared, #1- #5 from reagent solution standards, #6 - #7 of soil solution standards, #6 - #7 of soil extracts.extracts.

Reagent standard solutions Reagent standard solutions balanced ionic strength.balanced ionic strength.

Laboratories analyzed for P, K, Ca, Laboratories analyzed for P, K, Ca, Mg, Na and Zn each in triplicate in Mg, Na and Zn each in triplicate in ALP Cycle 12.ALP Cycle 12.

Miller, 2011

11 Submitted ALP Program Cycle 12. Bottles Submitted ALP Program Cycle 12. Bottles #6 and #7 soil extracts of ALP of SRS-0802 #6 and #7 soil extracts of ALP of SRS-0802 and SRS-0715.and SRS-0715.

Mehlich 3 P Calibration EvaluationMehlich 3 P Calibration Evaluation

An evaluation of M3 3 solutions was conducted in ALP An evaluation of M3 3 solutions was conducted in ALP Cycle 12, 12 labs participating. Cycle 12, 12 labs participating.

ICP Labs 12, sorted by low standard

Miller, 2011

IDID11 P P (ppm)(ppm)

Bottle #1Bottle #1 8.28.2




Bottle #5Bottle #5 00

Lab Rank

1 2 3 4 5 6 7 8 9 10 11 12

M3

-P I

CP

mg/k

g

0

20

40

60

80

100

120

Bottle #1 Bottle #2Bottle #3Bottle #4

Lab #12 has P Lab #12 has P precision issue precision issue across standardsacross standards

Mehlich 3 K Calibration EvaluationMehlich 3 K Calibration EvaluationICP Labs, 16, sorted by mid range standard

An evaluation of M3 solutions was conducted in An evaluation of M3 solutions was conducted in ALP cycle 12, 16 labs participating. ALP cycle 12, 16 labs participating.

Miller, 2011

IDID11 K K (ppm)(ppm)






1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

K M

-3 m

g/k

g

0

50

100

150

200

400500600

Bottle #1Bottle #2Bottle #3Bottle #4

Lab Rank Labs #15 and #16 Labs #15 and #16 have high bias issues, have high bias issues, all standardsall standards

Mehlich 3 Phosphorus Calibration EvaluationMehlich 3 Phosphorus Calibration Evaluation

Miller, 2011


A performance report for M3 A performance report for M3 analyses was provided to each analyses was provided to each ALP participating laboratory.ALP participating laboratory.

U6288AU6288A 1.041.04 -0.02-0.02 0.99950.9995

U6304AU6304A 0.9560.956 -0.26-0.26 0.99910.9991

U6322AU6322A 0.9130.913 -0.10-0.10 0.99970.9997

U6333AU6333A 0.8100.810 0.170.17 0.99990.9999

U6336AU6336A 1.041.04 1.81.8 0.99680.9968

U6356AU6356A 0.9670.967 0.210.21 0.99980.9998

U6718AU6718A 1.121.12 1.41.4 0.99990.9999

U6791AU6791A 1.081.08 0.570.57 0.99980.9998

U9814AU9814A 0.9680.968 0.180.18 0.99980.9998

U6816AU6816A 1.051.05 -0.04-0.04 0.99990.9999

Lab IDLab ID SlopeSlope InterceptIntercept RR22

Mehlich 3 ICP Phosphorus EvaluationMehlich 3 ICP Phosphorus EvaluationCalibration Evaluation – 5 standards

Miller, 2011


Ten of twelve reporting labs. Highlighted values indicate deviation from known calibration standards.

IDID11 M3 P M3 P SPECSPEC (ppm)(ppm)

M3 P M3 P ICPICP (ppm)(ppm)

MeanMean StdStd MeanMean StdStd

Bottle #6Bottle #6 12.612.6 1.01.0 18.3 18.3 ** 1.01.0

Bottle #7Bottle #7 19.019.0 0.60.6 51.6 51.6 ** 1.81.8

Mehlich 3 Phosphorus EvaluationMehlich 3 Phosphorus Evaluation Soil extract comparisonSoil extract comparison

Miller, 2011

11 Bottles #6 and #7 soil extracts of ALP soil SRS-0802 and SRS-0715. Bottles #6 and #7 soil extracts of ALP soil SRS-0802 and SRS-0715. Mean values significant different at the 0.05 level based on twelve labs, Mean values significant different at the 0.05 level based on twelve labs, triplicate.triplicate.


SummarySummary

Miller, 2011

NRP associated with soils with low pH, high sand NRP associated with soils with low pH, high sand content and low silt contents. Location specific. content and low silt contents. Location specific. Impact on recommendations and P index tool (PLAT).Impact on recommendations and P index tool (PLAT).

Evaluation of M3 P calibration standards show that 4 Evaluation of M3 P calibration standards show that 4 of 12 of labs have P calibrations that deviate greater of 12 of labs have P calibrations that deviate greater than 5% from the known calibration slope. than 5% from the known calibration slope.

M3 K show that 5 of 16 labs show K calibration M3 K show that 5 of 16 labs show K calibration deviations greater than 5% from the known deviations greater than 5% from the known calibration slope.calibration slope.

Future workFuture work

Miller, 2011

ALP will include Mehlich 1 elemental standard ALP will include Mehlich 1 elemental standard calibration solutions for Cycle 16, for P, K, Ca, Mg, Mn, calibration solutions for Cycle 16, for P, K, Ca, Mg, Mn, and Zn. Solutions to be analyzed in triplicate for the and Zn. Solutions to be analyzed in triplicate for the evaluation of bias and precision.evaluation of bias and precision.

Thank youThank youfor your timefor your timeand attentionand attention

mehlich 3 evaluation

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