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Analysis of soil nutrient content
2022-06-23 10:38:35   


overview


    Plant growth requires 17 elements which are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, copper, iron, manganese, zinc, molybdenum, boron, chlorine, silicon. Among them, carbon, hydrogen, and oxygen come from air and water, and the rest are from the soil. Therefore, the main and trace elements in the soil are particularly important for the growth of plants. A variety of analytical methods are usually used to analyze elemental contents, including combustion iodometric method to measure sulfur content, atomic absorption spectrophotometry used to analyze potassium, calcium, magnesium, copper, iron, manganese, zinc and other metal elements, Kjeldahl nitrogen analyzer to analyze nitrogen content in soil, and plasma emission spectrometry. These methods require digestions of soil sample into solutions, which are complicated in sample processing, complicated in instrument operation, and low in efficiency.

   Monochromatic excitation X-ray fluorescence spectrometer MERAK-SC,it's content analysis of major elements and trace elements such as sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, manganese, iron, and zinc in soil samples can be completed with the Monochromatic excitation energy dispersive X-ray fluorescence spectrometer MERAK-SC,which has the advantages of simple sample processing, fast analysis speed, high precision and low cost, and it is a powerful tool for the detection of nutrient elements in soil.

Technical principle
(1)
Monochromatic  excitation technology


MERAK-SC perfectly combines the monochromatic technology of the fully focused hyperboloid curved crystal with the secondary target. The characteristic X-rays of the target are monochromated by hyperboloid curved crystal and then diffracted and focused on a point of the sample, which greatly reduces the interference of the background of continuous scattered rays in the X-ray tube emission spectrum, improveing the element detection signal-to-noise ratio. MERAK-SC makes up for the lack of sensitivity of traditional energy dispersive X-ray fluorescence spectrometers to light elements. Monochromatic excitation X-ray fluorescence spectrometer realizes the detection and analysis of trace elements. (Invention patent: 201510970857.0).

(2)Fast Fundamental Parameter Method


Fundamental parameter method (FP) is a cutting-edge technology of XRF analysis. It establishes a basic parameter library and a series of mathematical models for the clear physical phenomena of X-ray fluorescence physics, and directly obtains the content of each element in the sample through a large number of calculations. The complexity and uncertainty of quantitative analysis due to XRF matrix effect, inter-element absorption enhancement effect, spectral line overlap interference, and various detector effects are resolved, and the quantitative analysis of sample elements in the absence of standard samples is realized. The Fundamental parameter method 2.0(FP2.0) developed by Beijing Ancoren Co., Ltd., not only uses the basic parameter library, but also establishes a series of mathematical models to improve the quantitative analysis level, which is in an international leading position in terms of sample adaptability, quantitative accuracy, and scalability.

Performance data
(1)Linearity
The linearity is established by the method of least squares using the calculated value of Fast FP and the certified value of 20 soil reference material. The correlation coefficient R² of each element (or oxide) is between 0.970 and 0.999.



 
(2)Repeatability
The repeatability results of soil standard sample GBW(E)070011 tested by MERAK-SC with FP2.0 are as follows:
                           Table 1: Repeatability test data for soil standard samples 


 Element
 
Al2O3
(%)
Na2O
(%)
MgO
(%)
CaO
(%)
Fe2O3
(%)
P
(mg/kg)
S
( mg/kg))
Ti
(%)
V
( mg/kg))
Cr
( mg/kg))
Mn
( mg/kg))
Ni
( mg/kg))
GBW(E)070011
Standard value
16.30 0.44 2.02 2.92 8.27 636 / 0.414 138 101 0.164 45.9
1 16.97 0.472 1.983 2.927 8.145 610.1 171.5 0.443 123.1 107.7 0.164 42.56
2 16.98 0.497 1.987 2.932 8.112 606.3 176.6 0.449 146.4 106.2 0.164 43.47
3 16.98 0.474 1.992 2.924 8.125 605.5 174.9 0.441 124.0 108.4 0.164 43.10
4 16.97 0.495 1.986 2.915 8.123 601.4 178.6 0.444 133.0 112.3 0.164 42.80
5 16.97 0.482 1.999 2.929 8.120 599.3 172.7 0.444 129.0 104.2 0.165 42.40
6 16.98 0.470 1.983 2.922 8.119 609.6 173.6 0.447 127.4 107.4 0.164 43.88
7 16.97 0.489 1.986 2.933 8.120 601.6 179.8 0.440 128.9 102.1 0.164 44.02
8 16.97 0.477 1.986 2.928 8.120 601.8 174.7 0.439 122.0 103.4 0.164 41.52
9 16.98 0.492 1.996 2.927 8.108 602.9 174.9 0.442 124.2 101.9 0.164 38.66
10 16.99 0.461 1.987 2.925 8.122 604.5 181.3 0.449 132.9 104.5 0.165 42.54
11 16.98 0.471 1.977 2.916 8.123 611.8 178.4 0.440 128.9 104.9 0.164 41.01
12 16.98 0.494 1.986 2.910 8.112 607.8 178.1 0.442 144.2 105.6 0.164 42.61
13 16.99 0.480 1.977 2.911 8.118 609.5 182.9 0.442 129.3 108.7 0.164 42.18
14 16.99 0.487 2.006 2.916 8.108 617.9 180.4 0.441 123.3 105.8 0.164 41.15
SD 0.008 0.011 0.008 0.0076 0.0092 5.0626 3.43 0.003 7.463 2.818 0.0004 1.3811
Avg 16.98 0.48 1.99 2.92 8.12 606.43 177.0 0.44 129.76 105.94 0.16 42.28

































 
(3)Accuracy
                                        Table 2: Accuracy comparison of soil standard samples
Element Al2O3
(%)
SiO2
(%)
Na2O
(%)
MgO
(%)
CaO
(%)
Fe2O3
(%)
P
(%)
Ti
(%)
Cr
( mg/kg )
Mn
(%)
Ni
( mg/kg )
S
(%)
C
l(%)
GBW(E)070005 13.93 61.34 1.51 1.88 2.99 6.36 0.070 0.455 89.90 0.118 60.80 / /
Test value 13.74 62.90 1.36 1.87 2.86 6.17 0.067 0.440 86.06 0.113 75.72 / /
GBW(E)070007 14.00 63.00 2.39 1.46 4.82 4.64 0.062 0.350 35.00 0.072 18.60 / /
Test value 13.62 62.23 2.21 1.44 4.72 4.44 0.062 0.352 45.11 0.071 20.43 / /
GBW(E)070008 14.32 60.57 1.48 2.32 3.58 6.95 0.047 0.412 84.30 0.210 333.0 / /
Test value 14.25 61.34 1.41 2.11 3.27 6.47 0.045 0.403 79.00 0.187 312.9 / /
GBW(E)070010 14.86 59.51 1.19 1.87 3.12 6.99 0.061 0.453 87.00 0.107 55.20 / /
Test value 15.14 60.25 1.02 1.87 3.16 6.87 0.057 0.460 84.77 0.106 47.30 / /
GSS-5 21.58 52.57 0.12 0.61 0.10 12.62 0.039 0.629 118.0 0.136 40.00 0.041 0.010
Test value 21.84 51.52 0.19 0.65 0.16 12.01 0.039 0.618 130.7 0.138 35.83 0.034 0.097
GSS-13 11.76 64.88 1.86 2.05 5.00 4.11 0.083 0.382 65.00 0.058 28.50 0.016 0.008
Test value 11.69 65.11 1.79 2.08 5.22 4.42 0.085 0.386 74.91 0.060 30.24 0.024 0.016
GSS-18 10.56 60.40 3.05 2.58 6.80 3.63 0.587 0.320 55.00 0.053 25.00 0.700 0.780
Test value 10.54 61.33 3.27 2.65 6.89 4.05 0.061 0.343 62.03 0.054 25.61 0.699 0.780
























 


Table 3: Comparison of sulfur content in actual soil samples by combustion method and HS XRF

Sample No 20N3100003 20N3100006 20N3100015 20N3100016 20N2620009 20N2620023 20N2620031 20N2620038 20N2620040 20N2620042 20N2620047
Combustion method test value 0.26% 0.88% 0.25% 0.66% 0.17% 0.16% 0.13% 0.12% 0.11% 0.18% 0.13%
HS XRF test value 0.27% 0.92% 0.27% 0.65% 0.17% 0.16% 0.12% 0.11% 0.12% 0.19% 0.13%
Relative deviation 1.31% 2.22% 3.29% -0.53% 1.46% 0 -1.59% -3.93% 2.18% 0.54% 0.39%


Sample handling


Features and advantages

   Stability


Stable analysis data can be obtained within 1 hour of startup, and it have excellent repeatability in continuous testing, day testing and long-term testing.


   
Accuracy

FP 2.0 eliminates the analysis error caused by the difference of sample matrix and spectral line interference through theoretical calculation, only a few standard (fixed value) samples are used to obtain accurate quantitative results.

   Low consumption


There is need to consume gas, liquid nitrogen refrigeration, vacuum, etc., to achieve long-term operation with low failure rate.


   fast

 The nutrient content analysis of a soil sample can be completed in as little as 60 seconds.

   Extend


Scalable analysis of Na-Zn element content in various samples.



Original statement:
This article is the original work of ancoren company except for the quotation. If it is forwarded and quoted, the source must be indicated, otherwise it may involve infringement. For more detailed technical information, please consult the staff of Ancoren.