Do we really need large spectral libraries for the assessment of soil organic carbon at local scale?
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http://www.fao.org/globalsoilpartnership This presentation was made during the International Workshop "Soil Spectroscopy: the present and future of Soil Monitoring" that took place at FAO HQ Rome, Italy from 4-6 December 2013. This presentation was made by César Guerrero, Johanna Wetterlind, Bo Stenberg, Fernando T.Maestre, Raphael A. ViscarraRossel, Abdul M. Mouazen, BoyanKuang, RaúlZornoza & J.D. Ruiz-Sinoga, and it has the objective to present Do we really need large spectral libraries for the assessment of soil organic carbon at local scale. ©FAO: http://www.fao.org
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Do we really need large spectral libraries for the assessment of soil organic carbon at local scale?
- 1. Do we really need large spectral libraries for the assessment of soil organic carbon at local scale? 1 University Miguel Hernandez of Elche (Spain); 2 SLU (Sweden); 3 University Rey Juan Carlos (Spain); 4 CSIRO – Land & Water (Australia); 5 Cranfield University (UK); 6 University Polytechnic Cartagena (Spain); 7 University of Málaga (Spain). César Guerrero1, Johanna Wetterlind2, Bo Stenberg2, Fernando T. Maestre3, Raphael A. Viscarra Rossel4, Abdul M. Mouazen5, Boyan Kuang5, Raúl Zornoza6, J.D. Ruiz-Sinoga7
- 2. Introduction * Many times, we need to analyze a large number of samples collected at local scale (i.e., collected in a target site). * Options and approaches for local-scale assessment with NIR spectroscopy: i) LOCAL models (spectrum-specific model) • Models constructed with similar spectra • Expensive: a large library is needed for select enough similar spectra ii) Geographically local model (site-specific model) • Models constructed with similar samples (similar matrix) • Expensive approach: these models are only valid for the target site iii) Large-scale models (regional, national, continental…) • A large model is not a guarantee of accurate predictions (large variability) • Prone to include non-linear patterns: biased predictions • We can apply “spiking”
- 3. Introduction SOC NIR spectra Y X SOC NIR spectra Y X Kennard-Stone algorithm Spiked Calibration Spectral Library Target Site Prediction Set Calibration R2, RMSEP, bias, SEP, RPD Spectral Library Target Site Prediction Set ŷ R2, RMSEP, bias, SEP, RPD ŷ Spiking Subset PLS-R PLS-R Target site (unknown) Target site (unknown) SOC ? SOC ? Spiking - Useful approach when large-scale models (regional or national) are used at local scale (in a target site). - This approach ensures that model contains similar samples (to those to be predicted). - Implies analytical efforts: the spiking subset must be analyzed with the reference method. - The spiking subset should be small: small contribution on the model (especially if the calibration is big). PLS-RPLS-R Unspiked Spiking X X Spiking subset
- 4. Kennard-Stone algorithm Spiked Calibration with extra-weighting Spectral Library Target Site Prediction Set Copies Spiking Subset Spiking subset extra-weighted Spiking Subset Spiking Subset Spiking Subset Spiking Subset PLS-R
- 5. Spiking subset extra-weighted Spiking SOC NIR spectra Y X Copy Paste Paste Paste Paste copies Library samples Spiking subset cross-validation 0 2 4 6 8 10 0 2 4 6 8 10 Spiking cross-validation 0 2 4 6 8 10 0 2 4 6 8 10 Spiked Calibration with extra-weighting Spectral library Target Site Prediction Set Copies Kennard -Stone algorithm
- 6. 0 2 4 6 8 10 0 2 4 6 8 10 Spiking subset extra-weighted SOC NIR spectra Y X Copy Paste Paste Paste Paste copies Library samples Spiking subset cross-validation the calibration is forced to fit better the spiking subset Spiking cross-validation 0 2 4 6 8 10 0 2 4 6 8 10 Spiking + extra-weighting Spiked Calibration with extra-weighting Spectral library Target Site Prediction Set Copies Kennard -Stone algorithm
- 7. SOC NIR spectra Y X SOC NIR spectra Y X Target site (unknown) Target site (unknown) SOC ? SOC ? PLS-R PLS-R X X Spiking subset (n=8) SOC NIR spectra Y X Target site (unknown) SOC ? PLS-R X Spiking subset (n=8) Copies = Extra weight Unspiked calibration Spiked calibration Spiked calibration with Extra-weight Unspiked Calibration Spectral library Target Site Prediction Set Spiked Calibration Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting Spectral library Target Site Prediction Set Copies Calibration types
- 8. Unspiked Spiking Spiking & Extra-weighting Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 9. Unspiked National set Spain n=1096 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 10. Unspiked National set Spain n=1096 Sweden n=125 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 11. Unspiked National set Spain n=1096 Valencia n=121 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 12. Unspiked National set Spain n=1096 Forest, Alicante n=130 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 13. Unspiked National set Spain n=1096 UK n=104 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 14. Unspiked National set Spain n=1096 Forest, Murcia n=156 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 15. Unspiked National set Spain n=1096 Gypsipherous n=95 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 16. Unspiked National set Spain n=1096 Almería (mica schists) n=60 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 17. Unspiked National set Spain n=1096 Cuenca n=55 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 18. Unspiked National set Spain n=1096 Palencia n=55 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 19. Unspiked National set Spain n=1096 Total n=901 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods R2, RMSEP, bias, SEP, RPIQ, RPD
- 20. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 21. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 22. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Sweden n=125
- 23. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Valencia n=121
- 24. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Forest, Alicante n=130
- 25. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods UK n=104
- 26. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Forest, Murcia n=156
- 27. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Gypsipherous n=95
- 28. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Almería (mica schists) n=60
- 29. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Cuenca n=55
- 30. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Palencia n=55
- 31. National set Spain n=1096 Total n=901 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods R2, RMSEP, bias, SEP, RPIQ, RPD
- 32. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 33. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 34. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Sweden n=125
- 35. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Valencia n=121
- 36. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Forest, Alicante n=130
- 37. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods UK n=104
- 38. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Forest, Murcia n=156
- 39. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Gypsipherous n=95
- 40. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Almería (mica schists) n=60
- 41. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Cuenca n=55
- 42. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods Palencia n=55
- 43. National set Spain n=1096 Total n=901 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods R2, RMSEP, bias, SEP, RPIQ, RPD
- 44. National set Spain n=1096 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 45. Predictions: national set (n=1096) 0.85 0.87 0.96 Unspiked Spiked Spiked EW 2.59 2.22 0.71 Unspiked Spiked Spiked EW 1.34 1.56 4.89 Unspiked Spiked Spiked EW 1.65 1.23 0.21 Unspiked Spiked Spiked EW R2 RMSEP (%SOC) |Bias| (%SOC) RPIQ Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901
- 46. Predictions: national set (n=1096) 0.85 0.87 0.96 Unspiked Spiked Spiked EW 2.59 2.22 0.71 Unspiked Spiked Spiked EW 1.34 1.56 4.89 Unspiked Spiked Spiked EW R2 RMSEP (%SOC) RPIQ Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Spiked Spiked & extra-weight Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked n=901 n=901 1.65 1.23 0.21 Unspiked Spiked Spiked EW |Bias| (%SOC)
- 47. Predictions: national set (n=1096) 0.85 0.87 0.96 Unspiked Spiked Spiked EW 2.59 2.22 0.71 Unspiked Spiked Spiked EW 1.34 1.56 4.89 Unspiked Spiked Spiked EW R2 RMSEP (%SOC) RPIQ Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 n=901 1.65 1.23 0.21 Unspiked Spiked Spiked EW |Bias| (%SOC)
- 48. Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 49. 33 % National set Spain n=362 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 50. 1.56 0.95 0.20 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Predictions: 33% national set (n=362) R2 RMSEP (%SOC) RPIQ 0.85 0.90 0.96 Unspiked Spiked Spiked EW 2.57 1.85 0.71 Unspiked Spiked Spiked EW 1.35 1.87 4.90 Unspiked Spiked Spiked EW Unspiked Spiked Spiked & extra-weight n=901 |Bias| (%SOC)
- 51. 1.56 0.95 0.20 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Predictions: 33% national set (n=362) R2 RMSEP (%SOC) RPIQ 0.85 0.90 0.96 Unspiked Spiked Spiked EW 2.57 1.85 0.71 Unspiked Spiked Spiked EW 1.35 1.87 4.90 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 |Bias| (%SOC)
- 52. Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Predictions: 33% national set (n=362) R2 RMSEP (%SOC) RPIQ 0.85 0.90 0.96 Unspiked Spiked Spiked EW 2.57 1.85 0.71 Unspiked Spiked Spiked EW 1.35 1.87 4.90 Unspiked Spiked Spiked EW 1.56 0.95 0.20 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 n=901 |Bias| (%SOC)
- 53. Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 54. Provincial set (Alicante) n=147 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 55. 2.88 0.11 0.04 Unspiked Spiked Spiked EW Predictions: provincial set (n=147) R2 RMSEP (%SOC) RPIQ 0.18 0.96 0.97 Unspiked Spiked Spiked EW 4.97 0.66 0.55 Unspiked Spiked Spiked EW 0.70 5.28 6.30 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 |Bias| (%SOC)
- 56. 2.88 0.11 0.04 Unspiked Spiked Spiked EW Predictions: provincial set (n=147) R2 RMSEP (%SOC) RPIQ 0.18 0.96 0.97 Unspiked Spiked Spiked EW 4.97 0.66 0.55 Unspiked Spiked Spiked EW 0.70 5.28 6.30 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 |Bias| (%SOC)
- 57. Predictions: provincial set (n=147) R2 RMSEP (%SOC) RPIQ 0.18 0.96 0.97 Unspiked Spiked Spiked EW 4.97 0.66 0.55 Unspiked Spiked Spiked EW 0.70 5.28 6.30 Unspiked Spiked Spiked EW 2.88 0.11 0.04 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 n=901 |Bias| (%SOC)
- 58. Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 59. Geograph. local set (Alicante) n=88 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 60. 1.80 0.06 0.01 Unspiked Spiked Spiked EW Predictions: Geographical local set (n=88) R2 RMSEP (%SOC) RPIQ 0.17 0.96 0.96 Unspiked Spiked Spiked EW 4.45 0.65 0.60 Unspiked Spiked Spiked EW 0.78 5.34 5.75 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 |Bias| (%SOC)
- 61. Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Predictions: Geographical local set (n=88) R2 RMSEP (%SOC) RPIQ 0.17 0.96 0.96 Unspiked Spiked Spiked EW 4.45 0.65 0.60 Unspiked Spiked Spiked EW 0.78 5.34 5.75 Unspiked Spiked Spiked EW 1.80 0.06 0.01 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 |Bias| (%SOC)
- 62. Predictions: Geographical local set (n=88) R2 RMSEP (%SOC) RPIQ 0.17 0.96 0.96 Unspiked Spiked Spiked EW 4.45 0.65 0.60 Unspiked Spiked Spiked EW 0.78 5.34 5.75 Unspiked Spiked Spiked EW 1.80 0.06 0.01 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 n=901 |Bias| (%SOC)
- 63. Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 64. 50% Provincial set n=73 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 65. 2.59 0.02 0.03 Unspiked Spiked Spiked EW Predictions: 50% provincial set (n=73) R2 RMSEP (%SOC) RPIQ 0.36 0.96 0.97 Unspiked Spiked Spiked EW 3.82 0.60 0.55 Unspiked Spiked Spiked EW 0.91 5.81 6.25 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 |Bias| (%SOC)
- 66. 2.59 0.02 0.03 Unspiked Spiked Spiked EW Predictions: 50% provincial set (n=73) R2 RMSEP (%SOC) RPIQ 0.36 0.96 0.97 Unspiked Spiked Spiked EW 3.82 0.60 0.55 Unspiked Spiked Spiked EW 0.91 5.81 6.25 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 |Bias| (%SOC)
- 67. Predictions: 50% provincial set (n=73) R2 RMSEP (%SOC) RPIQ 0.36 0.96 0.97 Unspiked Spiked Spiked EW 3.82 0.60 0.55 Unspiked Spiked Spiked EW 0.91 5.81 6.25 Unspiked Spiked Spiked EW 2.59 0.02 0.03 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 n=901 |Bias| (%SOC)
- 68. Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 69. Geograph. local set #2 (Guadalajara) n=40 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 70. 6.59 0.04 0.01 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 40 80 120 Predictions: Geographical local set #2 (n=40) R2 RMSEP (%SOC) RPIQ 0.00 0.95 0.96 Unspiked Spiked Spiked EW 19.92 0.70 0.66 Unspiked Spiked Spiked EW 0.17 4.94 5.28 Unspiked Spiked Spiked EW Unspiked Spiked Spiked & extra-weight n=901 |Bias| (%SOC)
- 71. 6.59 0.04 0.01 Unspiked Spiked Spiked EW Predictions: Geographical local set #2 (n=40) R2 RMSEP (%SOC) RPIQ 0.00 0.95 0.96 Unspiked Spiked Spiked EW 19.92 0.70 0.66 Unspiked Spiked Spiked EW 0.17 4.94 5.28 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 40 80 120 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 |Bias| (%SOC)
- 72. Predictions: Geographical local set #2 (n=40) R2 RMSEP (%SOC) RPIQ 0.00 0.95 0.96 Unspiked Spiked Spiked EW 19.92 0.70 0.66 Unspiked Spiked Spiked EW 0.17 4.94 5.28 Unspiked Spiked Spiked EW 6.59 0.04 0.01 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 40 80 120 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 n=901 |Bias| (%SOC)
- 73. Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 74. 25% Provincial set n=36 Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 75. 4.02 0.09 0.01 Unspiked Spiked Spiked EW Predictions: 25% provincial set (n=36) R2 RMSEP (%SOC) RPIQ 0.03 0.96 0.97 Unspiked Spiked Spiked EW 8.02 0.61 0.55 Unspiked Spiked Spiked EW 0.43 5.70 6.34 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 10 30 45 Unspiked Spiked Spiked & extra-weight n=901 |Bias| (%SOC)
- 76. 4.02 0.09 0.01 Unspiked Spiked Spiked EW Predictions: 25% provincial set (n=36) R2 RMSEP (%SOC) RPIQ 0.03 0.96 0.97 Unspiked Spiked Spiked EW 8.02 0.61 0.55 Unspiked Spiked Spiked EW 0.43 5.70 6.34 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 10 30 45 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 |Bias| (%SOC)
- 77. Predictions: 25% provincial set (n=36) R2 RMSEP (%SOC) RPIQ 0.03 0.96 0.97 Unspiked Spiked Spiked EW 8.02 0.61 0.55 Unspiked Spiked Spiked EW 0.43 5.70 6.34 Unspiked Spiked Spiked EW 4.02 0.09 0.01 Unspiked Spiked Spiked EW Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 10 30 45 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Measured SOC (%) 0 5 10 15 20 PredictedSOC(%) 0 5 10 15 20 Unspiked Spiked Spiked & extra-weight n=901 n=901 n=901 |Bias| (%SOC)
- 78. Unspiked Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiking Spiking & Extra-weighting Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Material & methods
- 79. 0.960.950.960.960.96 0.900.87 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.970.960.970.960.970.960.96 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.030.00 0.36 0.170.18 0.850.85 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 Determination coefficient (R2) Unspiked Spiked Spiked & extra-weight + Spectral library size - + Spectral library size - + Spectral library size - Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies
- 80. SEP (%SOC) + Spectral library size - + Spectral library size - + Spectral library size - 6.94 18.81 2.82 4.074.06 2.042.00 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.600.700.600.650.65 1.601.85 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.550.660.550.600.550.680.68 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Unspiked Spiked Spiked & extra-weight
- 81. |Bias| (%SOC) + Spectral library size - + Spectral library size - + Spectral library size - 4.02 6.59 2.59 1.80 2.88 1.561.65 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.090.040.020.060.11 0.95 1.23 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.010.010.030.010.040.200.21 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Unspiked Spiked Spiked & extra-weight
- 82. RMSEP (%SOC) + Spectral library size - + Spectral library size - + Spectral library size - 8.02 19.92 3.824.454.97 2.572.59 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.610.700.600.650.66 1.852.22 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 0.550.660.550.600.550.710.71 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Unspiked Spiked Spiked & extra-weight
- 83. RPD + Spectral library size - + Spectral library size - + Spectral library size - 0.39 0.16 0.830.710.63 1.231.22 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 5.20 4.50 5.30 4.874.81 1.70 1.42 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 5.79 4.81 5.70 5.24 5.75 4.474.46 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Unspiked Spiked Spiked & extra-weight
- 84. RPIQ + Spectral library size - + Spectral library size - + Spectral library size - 0.43 0.17 0.910.780.70 1.351.34 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 5.70 4.94 5.81 5.345.28 1.87 1.56 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 6.34 5.28 6.25 5.75 6.30 4.904.89 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Unspiked Spiked Spiked & extra-weight
- 85. RPIQ + Spectral library size - + Spectral library size - + Spectral library size - 0.43 0.17 0.910.780.70 1.351.34 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 5.70 4.94 5.81 5.345.28 1.87 1.56 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 6.34 5.28 6.25 5.75 6.30 4.904.89 Size36 Size40 Size73 Size88 Size147 Size362 Size1096 Unspiked Calibration (UC) Spectral library Target Site Prediction Set Spiked Calibration (SC) Spectral library Target Site Prediction Set Spiked Calibration with extra-weighting (SC+EW) Spectral library Target Site Prediction Set Copies Unspiked Spiked Spiked & extra-weight
- 86. Conclusions and recommendations • When a large-sized calibration is spiked, the spiking subset should be extra-weighted. Otherwise, the impact of the spiking subset will be low (especially if the spiking subset is small). • For local scale assessment, we don’t need the development of large spectral libraries: once spiked, the small-sized performed even better than the large-sized calibrations. • Do not focus your analytical efforts exclusively in the development of large-sized libraries and large-sized models. Split your analytical efforts in: • the development of small spectral libraries (a few regional samples) • the analysis of the spiking subsets • This approach (spiking + extra-weight) gives accurate results and small analytical efforts are needed (new users attracted, more soils would be studied, more benefits for soil management)
- 87. Thank you very much for your attention!! Criticisms welcomed!! Acknowledgements This work is part of the research project (Ref. CGL2011-27001) “Estimación de carbono orgánico en suelos mediante espectroscopía de infrarrojo cercano (NIR): estrategias para el desarrollo de modelos con aplicabilidad a escala nacional” financed by the Spanish “Ministerio de Economía y Competitividad” (Plan Nacional I+D+i)
- 88. R2 |bias| RMSEP SEP RPD RPIQ