Comparison of the analytical method for exchangable cations in soil and humus layer of the ICP Forests Manual with the German methods

Transcription

1 Combined Meeting of the Working Group QA/QC in Meeting of the Expert panel Soil and Soil Solution Labs with EP s Foliar, Deposition an Soil/Soil Solution 30. March, Zagreb, Croatia 29. March, Zagreb, Croatia Comparison of the analytical method for exchangable cations in soil and humus layer of the ICP Forests Manual with the German methods (Nils König, Göttingen, Germany) (with data of the German countries Niedersachsen, Hessen, Bayern, Baden-Württemberg und Thüringen) NW-FVA Northwest German Forest Research Station

2 Combined Meeting of the Working Group QA/QC in Meeting of the Expert panel Soil and Soil Solution Labs with EP s Foliar, Deposition an Soil/Soil Solution 30. March, Zagreb, Croatia 29. March, Zagreb, Croatia Problem: During the Second German Soil Survey (BZE II) 2 different methods for the determination of the exchangable cations in soil and humus layer have been used: percolation with 1 M NH4Cl for soil samples and percolation with 0,1 M BaCl2 for humus layer samples. On level II plots in Germany the samples are analyzed with the German methods and the ICP Forests method (extraction with 0,1 M BaCl2; for soil and humus layer). In Germany it is planned to organize the third German Soil Survey (BZE III) between 2022 and It was decided to evaluate all available data from German laboratories, which have analysed soil and humus layer samples twice with the German and the ICP Forests methods. If the comparison of the methods show that the data are convertable from one to the other method, the ICP Forests method should be used during the third German Soil Survey. If not the German methods should be used again because of the comparability of the data over time. NW-FVA Northwest German Forest Research Station N. König: Comparison of the analytical method for exchangable cations in soil and humus layer of the ICP Forests Manual with the German methods

3 Used methods in Germany and the EU: 1. Soil: Germany: 1 M NH4Cl-percolation (Ake-D) EU: 0,1 M BaCl2-extraction (AK-EU) 2. Humus layer: Germany: 0,1 M BaCl2-percolation (AKH-D) EU: 0,1 M BaCl2-extraction (AK-EU) AKe-D AKH-D

4 1. Comparison: Ake-D with AK-EU (soil samples) 1730 data sets from Niedersachsen, Hessen, Sachsen-Anhalt, Bayern and Baden-Württemberg - the data have been evaluated for each lab/country and all together - conversion factors have been calculated for each element - with these factors the data of the Ake-D method have been converted to the AK-EU method - the mean variations for all parameters have been estimated

5 Bayern 0,89 Ca Ba-Wü 0,98 NW-FVA 0,88 all together 0,89

6 Bayern 1,04 Mg Ba-Wü 0,94 NW-FVA 0,92 all together 0,98

7 Bayern 0,81 K Ba-Wü 0,72 NW-FVA 0,79 all together 0,79

8 Bayern 0,31 Na Ba-Wü 0,95 NW-FVA 0,80 all together 0,60 0,86

9 Bayern 0,71 Ba-Wü 0,62 Al NW-FVA alle 0,61 0,64

10 Bayern 0,79 Ba-Wü 0,41 Fe NW-FVA alle 0,58 0,47

11 Bayern 0,78 Mn Ba-Wü 0,64 NW-FVA 0,66 all together 0,72

12 Bayern 0,38 H Ba-Wü 0,60 NW-FVA 0,44 all together 0,49

13 Ca conversion of Ake-D data to AK-EU 0,98

14 Mg 0,98

15 K 0,94

16 Na 1,02

17 Al 0,96

18 Fe 0,89

19 Mn 0,95

20 H 0,88

21 CEC 0,96

22 BS 1,00

23 Control of the variation within the methods a. Ake-D (850 samples, soil) Ca Mg K Na

24 Control of the variation within the methods a. Ake-D (soil) Al Fe Mn H

25 Control of the variation within the methods b. Ak-EU (200 samples, soil) Ca Mg K Na

26 Control of the variation within the methods b. Ak-EU (soil) Al Fe Mn conclusion: - the reproducibility of both methods is good. - the variation within each method is much lower than between both methods

27 conclusion: - For the base cations the correlations are very good; conversion factors can be determined. - For the acid cations, specially for Al, the correlations are not so good; conversion factors can be determined, but the variation is high after conversion. - The variations within the methods are low. - After the conversion of the data from the German Ake-D method to the ICP Forests AK-EU method with the different conversion factors it can be seen that for low CEC the deviation for single samples can be more than 100 %. - Therefore Germany decided not to change the CEC method for the third German Soil Survey. - ICP Forests is asked to accept the converted data (Ake-D to AK-EU) from the third German Soil Survey, if there will be no funding for double analysis of the samples from the 16 x 16 km grid of the EU Soil Survey.

28 2. Comparison AKH-D with AK-EU (humus layer) 440 data sets from Niedersachsen, Hessen, Sachsen-Anhalt, Bayern and Thüringen - the data have been evaluated all together - conversion factors have been calculated for each element - with these factors the data of the Ake-D method have been converted to the AK-EU method - the mean variations for all parameters have been estimated

29 Ca 0,83 Ca 0,99 <= all samples Mg 1,00 Mg 1,08 => without samples with high Ca content

30 K 1,05 Na 0,95

31 Al Fe 0,78 1,05 Mn 1,16 conclusion: - High variation between the two methods - Good comparability for all elements except Al (slope 0,78)

32 CEC 0,89 <= all samples CEC 1,00 => without samples with high Ca content BS 1,00

33 Control of the variation within the methods a. Ak-EU (humus layer, 155 samples) Ca 1,00 Mg 1,00 K 1,00 Na 1,00

34 Control of the variation within the methods a. Ak-EU (humus layer, 155 samples) Al Fe 1,00 1,00 Mn 1,00

35 Ca Control of the variation within the methods b. AKH-D (humus layer, 375 samples) 0,99 Mg 0,99 K 0,98 Na 0,92

36 Al Control of the variation within the methods b. AKH-D (humus layer, 375 samples) 0,95 Fe 0,94 Mn 0,98 conclusion: - the reproducibility is good for the EU method and bad for the German method. - the variation between both methods comes from the variation of the German method

37 importance of exchangable Al (different humus layers) Ol Of Oh

38 Conclusion: - the reproducibility of the German AKH-D method is not very good. - the comparability of the German AKH-D and the ICP Forests AK-EU method is good; only for Al a conversion factor is needed. - the reproducibility of the ICP Forests method is much better and the handling of the method is much easier and cheeper than for the German AKH-D method. Because mainly the base cations are of interest in the humus layer in Germany it was decided to use only the ICP Forests AK-EU method for the third German Soil Survey. - The German AKH-D data of the second German Soil Survey will be converted to the ICP Forests AK-EU method for comparing the results of the second and third German Soil Survey for CEC in humus layers.