Simultaneous detection system and method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen

Abstract

The application provides a synchronous detection system and method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen, and relates to the technical field of soil component detection. The system comprises: a gas pump for blowing gas into a photolysis tank, blowing CO2 gas obtained by inorganic carbon acidolysis into a CO2 gas concentration detection module, and detecting a first CO2 gas concentration; a light source for emitting ultraviolet light or visible light to make organic carbon photolyze to generate CO2 gas after inorganic carbon acidolysis is completed; the gas pump blows the CO2 gas into the CO2 gas concentration detection module, detects a second CO2 gas concentration; and a computer obtains inorganic carbon content, organic carbon content, organic matter content, total carbon content and total nitrogen content based on a CO2 gas background concentration, the first CO2 gas concentration and the second CO2 gas concentration. The application can realize rapid and synchronous detection of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen in the field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil component detection, and particularly relates to a synchronous detection system and method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen. BACKGROUND

[0002] Soil carbon and nitrogen components (including organic matter, organic carbon, inorganic carbon, total carbon and total nitrogen) are key indicators for evaluating soil fertility, carbon storage and environmental quality. At present, the determination of these indicators mainly relies on laboratory analysis methods, such as dry combustion method (elemental analyzer), potassium dichromate oxidation method (Walkley-Black method), Kjeldahl nitrogen determination method, etc. Although these methods have high precision, they have the following limitations:

[0003] Inability to detect in situ in the field: Traditional methods rely on laboratory equipment (such as elemental analyzers, spectrometers, etc.), require sample transportation, pretreatment (grinding, drying, acidification, etc.), and take a long time (several hours to several days), making it difficult to meet the demand for rapid detection in the field.

[0004] Inability to detect multiple indicators simultaneously: Existing technologies usually require different methods to determine organic carbon, inorganic carbon and total nitrogen, such as: organic carbon usually adopts potassium dichromate oxidation method or elemental analysis method (which requires acid treatment to remove inorganic carbon); inorganic carbon adopts hydrochloric acid digestion-gasometric method or difference method; total nitrogen relies on Kjeldahl nitrogen determination method or elemental analyzer; resulting in complicated operation and limited data comparability between different methods.

[0005] Therefore, the existing technology is difficult to achieve in-situ, rapid and simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen in the field. SUMMARY

[0006] The present application provides a synchronous detection system and method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen, which solves the defect that it is difficult to detect the five indicators of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen in the field in-situ, rapidly and simultaneously in the prior art, and achieves the in-situ, rapid and simultaneous detection of the five indicators of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen in the field.

[0007] The present application provides a synchronous detection system for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen, comprising: a gas pump, a photolysis tank and a CO2 gas concentration detection module connected in sequence, the photolysis tank contains soil suspension mixed with acid solution of the soil to be detected, the photolysis tank is also provided with a light source, and the CO2 gas concentration detection module is in communication connection with a computer.

[0008] Before starting detection, the CO2 gas concentration detection module detects a CO2 gas background concentration in the environment;

[0009] When starting detection, the air pump blows air into the photolysis cell to blow the CO2 gas produced by inorganic carbon in the soil to be detected into the CO2 gas concentration detection module to detect a first CO2 gas concentration after inorganic carbon in the soil to be detected is carbonated;

[0010] After inorganic carbon in the soil to be detected is carbonated, the light source emits ultraviolet light or visible light to make the soil to be detected produce CO2 gas by photolysis of organic carbon; the air pump continues to blow air into the photolysis cell to blow the CO2 gas produced by photolysis of organic carbon in the soil to be detected into the CO2 gas concentration detection module to detect a second CO2 gas concentration after organic carbon in the soil to be detected is photolyzed;

[0011] The computer obtains the inorganic carbon content, organic carbon content, organic matter content, total carbon content and total nitrogen content in the soil to be detected based on the CO2 gas background concentration, the first CO2 gas concentration and the second CO2 gas concentration.

[0012] In some embodiments, the computer is specifically used for:

[0013] A first CO2 gas concentration difference value is obtained according to the first CO2 gas concentration and the CO2 gas background concentration; the inorganic carbon content in the soil to be detected is obtained according to the first CO2 gas concentration difference value and a first correction model of CO2 gas concentration and soil inorganic carbon;

[0014] A second CO2 gas concentration difference value is obtained according to the second CO2 gas concentration and the first CO2 gas concentration; the organic carbon content in the soil to be detected is obtained according to the second CO2 gas concentration difference value and a second correction model of CO2 gas concentration and soil organic carbon;

[0015] The organic matter content in the soil to be detected is obtained according to the organic carbon content in the soil to be detected and a correction coefficient between soil organic carbon and soil organic matter;

[0016] The total carbon content in the soil to be detected is obtained according to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected;

[0017] The total nitrogen content in the soil to be detected is obtained according to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, and a soil total nitrogen detection model; the soil total nitrogen detection model is a model taking soil inorganic carbon and soil organic carbon as input and taking soil total nitrogen as output.

[0018] In some embodiments, the acidic solution is a phosphate buffer solution.

[0019] In some embodiments, the solid-liquid ratio of the soil to be detected to the phosphate buffer solution is 1:80.

[0020] In some embodiments, the blowing time of the air pump is greater than or equal to 200 seconds when the inorganic carbon in the soil to be detected is decomposed.

[0021] In some embodiments, when the light source is used to emit ultraviolet light, an oxidant type photocatalyst or a semiconductor photocatalyst is added to the soil suspension.

[0022] In some embodiments, when the oxidant type photocatalyst is H2O2, the concentration of H2O2 is 500 mg / L.

[0023] In some embodiments, the catalytic reaction time of the ultraviolet light is 20 minutes.

[0024] In some embodiments, when the light source is used to emit visible light, a semiconductor photocatalyst is added to the soil suspension.

[0025] In some embodiments, the first correction model is wherein, represents the CO2 gas concentration, represents the soil inorganic carbon content.

[0026] In some embodiments, the second correction model is wherein, represents the CO2 gas concentration, represents the soil organic carbon content.

[0027] The present application also provides a soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection method based on the soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection system.

[0028] Based on the CO2 gas background concentration in the environment, the first CO2 gas concentration after inorganic carbon decomposition in the soil to be detected, and the second CO2 gas concentration after organic carbon photolysis in the soil to be detected, the inorganic carbon content, organic carbon content, organic matter content, total carbon content and total nitrogen content in the soil to be detected are obtained.

[0029] In some embodiments, the inorganic carbon content, the organic carbon content, the organic matter content, the total carbon content and the total nitrogen content in the soil to be detected are obtained based on the CO2 gas background concentration in the environment, the first CO2 gas concentration after inorganic carbon in the soil to be detected is decomposed, the second CO2 gas concentration after organic carbon in the soil to be detected is decomposed, including:

[0030] According to the first CO2 gas concentration difference and a first correction model of CO2 gas concentration and soil inorganic carbon, the inorganic carbon content in the soil to be detected is obtained.

[0031] According to the second CO2 gas concentration difference and a second correction model of CO2 gas concentration and soil organic carbon, the organic carbon content in the soil to be detected is obtained.

[0032] According to the organic carbon content in the soil to be detected and a correction coefficient between soil organic carbon and soil organic matter, the organic matter content in the soil to be detected is obtained.

[0033] According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, the total carbon content in the soil to be detected is obtained.

[0034] According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, and a soil total nitrogen detection model, the total nitrogen content in the soil to be detected is obtained; the soil total nitrogen detection model is a model taking soil inorganic carbon and soil organic carbon as input and taking soil total nitrogen as output.

[0035] The synchronous detection system and method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the application can convert inorganic carbon in soil into CO2 gas through acidolysis technology, detect the CO2 gas concentration to detect the inorganic carbon content in soil, realize rapid and selective detection of inorganic carbon, convert organic carbon in soil into CO2 gas through ultraviolet light / visible light catalysis, detect the CO2 gas concentration to detect the organic carbon content in soil, realize rapid in-situ conversion of organic carbon, calculate the soil organic matter content according to the correction coefficient between soil organic matter and soil organic carbon, avoid complex chemical extraction, obtain soil total carbon according to soil inorganic carbon and soil organic carbon, and according to the strong correlation between soil total nitrogen and soil organic matter, the soil total nitrogen content is inversely calculated, so that the time-consuming steps of the traditional Kjeldahl method are saved. The system has the advantages of low cost, small size and portability, and can rapidly and synchronously detect five indexes of soil organic matter, soil inorganic carbon, soil organic carbon, soil total carbon and soil total nitrogen in the field. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0037] Figure 1 It is a structural schematic diagram of the soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection system provided by the present application.

[0038] Figure 2 It is a relationship diagram between CO2 gas, soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the present application.

[0039] Figure 3 It is a solid-liquid ratio optimization result diagram of soil and phosphate buffer provided by the present application.

[0040] Figure 4 It is an influence result diagram of blowing time when inorganic carbon is converted into CO2 gas under different concentrations provided by the present application.

[0041] Figure 5 It is a correction model result diagram between inorganic carbon concentration and CO2 gas concentration provided by the present application.

[0042] Figure 6 It is an H2O2 concentration optimization result diagram provided by the present application.

[0043] Figure 7 It is an optimization result diagram of ultraviolet light photocatalytic reaction time provided by the present application.

[0044] Figure 8 It is a correction model result diagram between organic carbon concentration and CO2 gas concentration generated by ultraviolet light catalysis provided by the present application.

[0045] Figure 9 It is a flowchart of the soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection method provided by the present application.

[0046] Figure 10 It is a flowchart of the soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection method provided by the present application.

[0047] Figure 11 It is a detection result diagram of soil inorganic carbon provided by the present application.

[0048] Figure 12A detection result diagram of soil organic carbon provided by the present application.

[0049] Figure 13 A detection result diagram of soil organic matter provided by the present application.

[0050] Figure 14 A detection result diagram of soil total carbon provided by the present application.

[0051] Figure 15 A detection result diagram of soil total nitrogen provided by the present application.

[0052] Reference signs:

[0053] 10: photolysis tank; 20: air pump; 30: CO2 gas concentration detection module;

[0054] 40: light source; 50: computer. DETAILED DESCRIPTION

[0055] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0056] Figure 1 A structure schematic diagram of a synchronous detection system of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the present application is shown in FIG. 1, and the synchronous detection system of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the present application comprises a photolysis tank 10, an air pump 20, a CO2 gas concentration detection module 30, a light source 40 and a computer 50. Figure 1 The air pump 20, the photolysis tank 10 and the CO2 gas concentration detection module 30 are sequentially and circularly connected by air ports, the photolysis tank 10 contains soil suspension mixed by soil to be detected and acidic solution, the photolysis tank 10 is further provided with the light source 40, and the CO2 gas concentration detection module 30 is in communication connection with the computer 50.

[0057] Before starting detection, the CO2 gas concentration detection module 30 detects the background concentration of CO2 gas in the environment;

[0058] When starting detection, the air pump 20 blows air into the photolysis tank 10, so as to blow the CO2 gas obtained by acidolysis of inorganic carbon in the soil to be detected into the CO2 gas concentration detection module 30, and detect the first CO2 gas concentration after acidolysis of the inorganic carbon in the soil to be detected;

[0059] ​

[0060] After the inorganic carbon in the soil to be detected is completely decomposed, the light source 40 emits ultraviolet light or visible light to make the organic carbon in the soil to be detected photolyze to generate CO2 gas; the air pump 20 continues to blow air into the photolysis tank 10 to blow the CO2 gas generated by the photolysis of the organic carbon in the soil to be detected into the CO2 gas concentration detection module to detect the second CO2 gas concentration after the photolysis of the organic carbon in the soil to be detected.

[0061] The computer 50 obtains the inorganic carbon content, the organic carbon content, the organic matter content, the total carbon content and the total nitrogen content in the soil to be detected based on the CO2 gas background concentration, the first CO2 gas concentration and the second CO2 gas concentration.

[0062] Specifically, before starting the detection, the CO2 gas concentration detection module 30 is used to detect the CO2 gas concentration in the environment, which is recorded as the CO2 gas background concentration The CO2 gas background concentration is transmitted to the computer 50 by the CO2 gas concentration detection module 30.

[0063] The photolysis tank 10 contains the soil suspension of the soil to be detected mixed with the acidic solution. The inorganic carbon-containing substances (such as carbonate and bicarbonate) in the soil react with H + to generate carbonic acid, which decomposes under acidic conditions to generate CO2 gas.

[0064] The photolysis tank 10, the air pump 20 and the CO2 gas concentration detection module 30 are connected in a closed loop through a hose, that is, the air outlet of the air pump 20 is connected with the air inlet of the photolysis tank 10, the air outlet of the photolysis tank 10 is connected with the air inlet of the CO2 gas concentration detection module 30, and the air outlet of the CO2 gas concentration detection module 30 is connected with the air inlet of the air pump 20 to form a closed loop air path. In some embodiments, a water vapor filter can be installed in the connecting pipe between the air outlet of the photolysis tank 10 and the air inlet of the CO2 gas concentration detection module 30 to prevent water vapor carried by the air blowing in the photolysis tank 10 from entering the air cavity of the CO2 gas concentration detection module 30.

[0065] When starting the detection, the air pump 20 is turned on to blow air into the photolysis tank 10, to blow the CO2 gas converted from the inorganic carbon out of the soil suspension, into the CO2 gas concentration detection module 30, and to make the CO2 gas concentration detection module 30 detect the CO2 gas concentration. After the CO2 gas comes out of the CO2 gas concentration detection module 30, it enters the air inlet of the air pump 20 through the hose, and then is blown into the soil suspension in the photolysis tank 10 through the air outlet of the air pump 20. The air pump 20 continuously works to blow the CO2 gas converted from the inorganic carbon in the soil back and forth until the detection result of the CO2 gas concentration detected by the CO2 gas concentration detection module 30 remains stable, and the CO2 gas concentration at this time is recorded as the first CO2 gas concentration after the inorganic carbon in the soil to be detected is carbonated . The CO2 gas concentration detection module 30 transmits the first CO2 gas concentration to the computer 50.

[0066] The inorganic carbon is decomposed to generate CO2 gas by adding acid, which can detect the inorganic carbon content in the soil and eliminate the interference of the inorganic carbon on the detection of the organic carbon in the soil.

[0067] In some embodiments, the air inlet of the photolysis tank 10 is close to the bottom of the photolysis tank 10, and the air outlet of the photolysis tank 10 is close to the top of the photolysis tank 10. Since the CO2 density is higher than that of air, the generated CO2 will naturally settle at the bottom of the photolysis tank 10. By taking air from the bottom, an upward air flow can be formed to directly push the high-concentration CO2 gas to the top, and then the CO2 gas enters the CO2 gas concentration detection module 30 through the air outlet at the top, thereby improving the detection accuracy of the CO2 gas concentration.

[0068] After the inorganic carbon in the soil to be detected is carbonated, the light source 40 is turned on to emit ultraviolet light or visible light. Under the irradiation of the light source 40, the organic matter in the soil will decompose, and the organic carbon in the soil will combine with oxygen atoms to generate CO2 gas. While the photolysis reaction is carried out, the air pump 20 continuously works to blow the CO2 gas generated in the photolysis tank 10 into the CO2 gas concentration detection module 30, so that the CO2 gas concentration detection module 30 detects the CO2 gas concentration. The light source 40 and the air pump 20 continuously work until the set time, and the CO2 gas concentration at this time is recorded as the second CO2 gas concentration after the organic carbon in the soil to be detected is photolyzed . The CO2 gas concentration detection module 30 transmits the second CO2 gas concentration to the computer 50.

[0069] It should be noted that the inorganic carbon content in the soil to be detected is detected first, which can eliminate the interference of the inorganic carbon on the detection of the organic carbon in the soil and ensure that all the CO2 generated in the ultraviolet light / visible light catalysis process is derived from the decomposition of organic matter.

[0070] In order to accurately detect the generated CO2 gas concentration, the CO2 gas concentration detection module 30 can adopt methods including but not limited to Tunable Diode Laser Absorption Spectroscopy (TDLAS) method, non-dispersive infrared spectroscopy method, fluorescence method, electrochemical method, etc. to detect the CO2 gas concentration.

[0071] Figure 2 is a relationship diagram between CO2 gas, soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the present application, as shown in Figure 2 The soil inorganic carbon (SIC) is decomposed into CO2 gas by adding acid, the soil organic carbon (SOC) is decomposed into CO2 gas by ultraviolet light / visible light catalysis, the soil organic carbon multiplied by a correction factor (1.724) obtains the soil organic matter (SOM), the soil organic matter has strong correlation with the soil total nitrogen (STN), and the soil total carbon (STC) includes the soil inorganic carbon and the soil organic carbon.

[0072] The computer 50 obtains the CO2 gas background concentration, the first CO2 gas concentration and the second CO2 gas concentration, the difference between the first CO2 gas concentration and the CO2 gas background concentration is the CO2 gas concentration generated by the decomposition of the soil inorganic carbon in the acid environment. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon.

[0073] The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon. The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of the soil organic carbon.

[0074] The computer 50 multiplies the soil organic carbon content in the soil to be detected by the correction factor (for example, 1.724) between the soil organic carbon and the soil organic matter to obtain the soil organic matter content in the soil to be detected. The computer 50 adds the soil inorganic carbon content in the soil to be detected and the soil organic carbon content in the soil to be detected to obtain the total carbon content in the soil to be detected.

[0075] The soil organic matter content has strong correlation with the soil total nitrogen content, and the computer 50 can obtain the total nitrogen content in the soil to be detected according to the soil organic matter content.

[0076] The synchronous detection system for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the application can convert inorganic carbon in the soil into CO2 gas through acidolysis technology, detect the inorganic carbon content in the soil by detecting the CO2 gas concentration, and realize rapid and selective detection of inorganic carbon; the synchronous detection system for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the application can convert organic carbon in the soil into CO2 gas through ultraviolet light / visible light catalysis, detect the organic carbon content in the soil by detecting the CO2 gas concentration, and realize rapid in-situ conversion of organic carbon; the synchronous detection system for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the application can calculate the soil organic matter content according to the correction coefficient of soil organic matter and soil organic carbon, and avoid complex chemical extraction; the synchronous detection system for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the application can obtain soil total carbon according to soil inorganic carbon and soil organic carbon, and obtain soil total nitrogen content by inversion according to the strong correlation between soil total nitrogen and soil organic matter, thereby saving the time-consuming steps of the traditional Kjeldahl method. The system has the advantages of low cost, small size and portability, and can rapidly and synchronously detect five indexes of soil organic matter, soil inorganic carbon, soil organic carbon, soil total carbon and soil total nitrogen in the field.

[0077] In some embodiments, the computer 50 is specifically configured to:

[0078] According to the first CO2 gas concentration and the CO2 gas background concentration, a first CO2 gas concentration difference value is obtained; according to the first CO2 gas concentration difference value and a first correction model of the CO2 gas concentration and soil inorganic carbon, the inorganic carbon content in the soil to be detected is obtained.

[0079] According to the second CO2 gas concentration and the first CO2 gas concentration, a second CO2 gas concentration difference value is obtained; according to the second CO2 gas concentration difference value and a second correction model of the CO2 gas concentration and soil organic carbon, the organic carbon content in the soil to be detected is obtained.

[0080] According to the organic carbon content in the soil to be detected and the correction coefficient between soil organic carbon and soil organic matter, the organic matter content in the soil to be detected is obtained.

[0081] According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, the total carbon content in the soil to be detected is obtained.

[0082] According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, and a soil total nitrogen detection model, the total nitrogen content in the soil to be detected is obtained; the soil total nitrogen detection model is a model taking soil inorganic carbon and soil organic carbon as input and taking soil total nitrogen as output.

[0083] Specifically, the first CO2 gas concentration and the CO2 gas background concentration The difference between the two values ​​represents the concentration of CO2 gas produced by the decomposition of inorganic carbon in the soil under acidic conditions, and is denoted as the first CO2 gas concentration difference. Computer 50 pre-constructs a first calibration model relating CO2 gas concentration and soil inorganic carbon. The first CO2 gas concentration difference is input into the first calibration model to obtain the inorganic carbon content in the soil to be tested.

[0084] Second CO2 gas concentration With the first CO2 gas concentration The difference between the two values ​​represents the concentration of CO2 gas produced by the photolysis of organic carbon in the soil, and is denoted as the second CO2 gas concentration difference. A second calibration model of CO2 gas concentration and soil organic carbon is pre-constructed by computer 50. The second CO2 gas concentration difference is input into the second calibration model to obtain the organic carbon content in the soil to be tested.

[0085] Computer 50 multiplies the organic carbon content in the soil to be tested by a correction factor (e.g., 1.724) between soil organic carbon and soil organic matter to obtain the organic matter content in the soil to be tested. Computer 50 then adds the inorganic carbon content and the organic carbon content in the soil to be tested to obtain the total carbon content in the soil to be tested.

[0086] Since the main component of total nitrogen in soil is organic nitrogen, soil organic matter content and soil total nitrogen content are strongly correlated. However, the correction factor between soil organic matter and soil total nitrogen is not fixed and is affected by soil type, unlike the correction factor between soil organic carbon and soil organic matter, which can be multiplied by a fixed factor.

[0087] Considering the strong correlation between soil organic matter content and total nitrogen content (i.e., a strong correlation between soil organic carbon and total nitrogen), while there is no correlation between soil inorganic carbon and total nitrogen, although soil inorganic carbon can reflect soil type information to some extent, a soil total nitrogen detection model is constructed using machine learning algorithms. This model uses soil inorganic carbon and soil organic carbon as inputs and soil total nitrogen as the output. Soil inorganic carbon is used to suppress interference caused by soil type differences, leading to more accurate detection of soil total nitrogen content. Machine learning algorithms include, but are not limited to, partial least squares, support vector machines, and random forest algorithms.

[0088] The simultaneous detection system for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon, and soil total nitrogen provided by this invention improves the detection accuracy of soil inorganic carbon through a first calibration model, improves the detection accuracy of soil organic carbon through a second calibration model, and further improves the detection accuracy of soil organic matter and soil total carbon. By constructing a soil total nitrogen detection model with soil inorganic carbon and soil organic carbon as inputs and soil total nitrogen as output, the accuracy of soil total nitrogen detection is improved.

[0089] The computer 50 inputs the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected into the soil total nitrogen detection model, to obtain the total nitrogen content in the soil to be detected.

[0090] The soil suspension obtained by mixing the soil to be detected with the acidic solution is described below.

[0091] In some embodiments, the acidic solution is a phosphate buffer solution.

[0092] Specifically, when the acidic solution is a phosphate buffer solution, the phosphate buffer solution stabilizes the pH of the soil suspension at 5.0, and can eliminate the influence of the pH difference between different types and different regions of soil samples on the CO2 generation efficiency.

[0093] In some embodiments, the solid-liquid ratio of the soil to be detected to the phosphate buffer solution is 1:80.

[0094] Specifically, unlike the homogeneous solution prepared by dissolving the soil sample with the dissolved organic matter, the soil sample is mixed with the phosphate buffer solution after being added to the soil sample, and the soil suspension is formed under the blowing condition. The soil suspension has poor light transmittance, which affects the propagation efficiency of ultraviolet light in the suspension, and further affects the efficiency of the photocatalytic decomposition of soil organic matter to generate CO2 gas, and finally affects the overall detection efficiency of soil organic carbon. The higher the amount of soil added, the greater the solid-liquid ratio of the soil to the phosphate buffer solution. Although the content of organic carbon in the suspension increases, the ultraviolet light catalytic reaction rate decreases, and the generation concentration of CO2 gas decreases.

[0095] The solid-liquid ratio of the soil to the phosphate buffer solution is optimized, Figure 3 is the optimization result graph of the solid-liquid ratio of the soil to the phosphate buffer solution provided by the present application, as shown in Figure 3 For the conversion of soil inorganic carbon, when the blowing time is fixed at 5 minutes, the generated CO2 gas concentration gradually increases as the solid-liquid ratio of the soil to the phosphate buffer solution increases from 1:160 to 1:20. This is because the increase in the amount of soil sample added increases the inorganic carbon content in the soil suspension. The conversion of inorganic carbon to CO2 only requires an acidic condition and does not require photocatalysis, so the concentration of CO2 gas released by acidolysis increases. However, for the conversion of soil organic carbon, as the solid-liquid ratio increases from 1:160 to 1:20, the generated CO2 gas concentration first increases and then decreases, and reaches a maximum value when the solid-liquid ratio is 1:80.

[0096] Therefore, the solid-liquid ratio of the soil to be detected to the phosphate buffer solution is set to 1:80. For example, the volume of the phosphate buffer solution is 40 mL, and therefore the optimal mass of the soil to be detected added is 0.5 g.

[0097] The detection principle of soil inorganic carbon is that the carbon-containing inorganic matter in the soil, such as carbonate and bicarbonate, is decomposed to CO2 under an acidic condition and in the presence of H+ The reaction occurs to generate carbonic acid, which will decompose into CO2 and H2O under acidic conditions, as shown in reactions 1-3. The inorganic carbon content in the soil can be detected according to the concentration of the generated CO2 gas. The specific details of the soil inorganic carbonolysis to generate CO2 gas are described in detail below.

[0098] (Reaction formula 1)

[0099] (Reaction formula 2)

[0100] (Reaction formula 3)

[0101] In some embodiments, the blowing time of the air pump 20 is greater than or equal to 200 seconds when the inorganic carbon in the soil to be detected is decomposed.

[0102] Specifically, the acid addition reaction time will affect the amount of CO2 gas generated, and in turn affect the detection results of soil inorganic carbon. In order to facilitate the release of generated CO2 gas from the solution, blowing is performed to the solution during detection. TDLAS is applied to detect the concentration of CO2 gas, sodium carbonate is used as the inorganic carbon source, and the inorganic carbon concentration is configured to be 1-200 mg / L. The blowing time (i.e., the acid decomposition reaction time) is optimized.

[0103] Figure 4 is the influence result graph of the blowing time when the inorganic carbon is converted to CO2 gas under different concentrations provided by the present application, and the optimization result is shown in Figure 4 As the blowing time increases, the concentration of the generated CO2 gas rapidly increases within 0-200 seconds, and the CO2 gas concentration is basically unchanged within 200-600 seconds; and for different concentrations of inorganic carbon of 1-200 mg / L, the change trend with the blowing time is basically the same, indicating that when the blowing time is 200 seconds, the reaction has reached an equilibrium state.

[0104] Therefore, in order to ensure that the reaction proceeds sufficiently, the blowing time of the air pump 20 is set to be greater than or equal to 200 seconds, for example, the blowing time is set to be 300 seconds, i.e., 5 minutes.

[0105] In some embodiments, the first correction model is wherein, represents the concentration of CO2 gas, represents the inorganic carbon content of the soil.

[0106] Specifically, the concentration of the generated CO2 gas when blowing for 5 minutes is recorded, and then the background CO2 gas concentration in the environment is deducted to obtain the CO2 gas concentration converted from inorganic carbon, which is the CO2 gas concentration generated by the decomposition of soil inorganic carbon in an acidic environment.

[0107] Linear fitting was performed on the inorganic carbon concentration and CO2 gas concentration. Figure 5 This is a graph showing the results of the calibration model between inorganic carbon concentration and CO2 gas concentration provided by this invention, as shown in the figure. Figure 5 As shown, the first correction model obtained is ,in, Indicates CO2 gas concentration. This indicates the inorganic carbon content of the soil. Within the inorganic carbon concentration range of 1–200 mg / L, the concentration of generated CO2 gas shows a good linear relationship with the inorganic carbon concentration. =0.9992), indicating that the concentration of inorganic carbon in the solution can be detected based on the concentration of CO2 gas generated by acid decomposition, laying the foundation for the detection of inorganic carbon in soil.

[0108] The principle behind detecting soil organic carbon is as follows: Ultraviolet / visible light photocatalysis is used to decompose soil organic matter, converting the organic carbon components into CO2 gas. The concentration of the generated CO2 gas is then used to detect the soil organic carbon content. Regardless of the specific photocatalytic technology used, the aim is to efficiently decompose carbon-containing organic matter in soil suspensions into CO2 gas; the concentration of CO2 gas is then used to detect the organic carbon content in the soil.

[0109] In some embodiments, when the light source 40 is used to emit visible light, a semiconductor photocatalyst is added to the soil suspension.

[0110] Specifically, for visible light catalysis, the emission wavelength of the light source 40 is within the visible light range. Visible light itself cannot decompose organic matter, so semiconductor photocatalysts such as titanium dioxide and zinc oxide, as well as graphene-doped titanium dioxide and zinc oxide-doped metal-organic framework materials, need to be added to the soil suspension. Under visible light irradiation, semiconductor photocatalysts can generate photogenerated holes and photogenerated electrons. Holes have strong oxidizing properties, which directly decompose organic matter on the one hand, and convert water molecules into hydroxyl radicals on the other hand, thereby decomposing organic matter. Under the combined action, carbon-containing organic matter in the soil suspension is efficiently converted into CO2 gas.

[0111] The following section uses ultraviolet photocatalysis technology as an example to detail the specifics of CO2 gas production from the photolysis of soil organic carbon.

[0112] In some embodiments, when the light source 40 is used to emit ultraviolet light, an oxidant-type photocatalyst or a semiconductor photocatalyst is added to the soil suspension.

[0113] Specifically, for ultraviolet light catalysis, the emission wavelength of the light source 40 can be 185 nm, 254 nm, etc. ultraviolet light. In order to improve the decomposition rate of soil organic matter, improve the detection efficiency of soil organic carbon, add oxidant type photolysis catalyst such as H2O2 and persulfate to the soil suspension, generate active substances with strong oxidation such as hydroxyl radicals and persulfate radicals, and improve the decomposition rate of organic matter and the generation rate of CO2 gas.

[0114] Alternatively, semiconductor photocatalysts such as titanium dioxide and zinc oxide, and semiconductor photocatalysts such as graphene-doped titanium dioxide and zinc oxide-doped metal organic framework materials are added to the soil suspension; the semiconductor photocatalyst can generate photo-generated holes and photo-generated electrons under the irradiation of ultraviolet light, and the holes have strong oxidation performance, which can directly decompose organic matter on the one hand, and convert water molecules into hydroxyl radicals, and then decompose organic matter; under the joint action, the carbon-containing organic matter in the soil suspension is efficiently converted into CO2 gas.

[0115] In some embodiments, when the oxidant type photolysis catalyst is H2O2, the concentration of H2O2 is 500 mg / L.

[0116] Specifically, under the condition of ultraviolet light irradiation, H2O molecules will be converted into H2O2, and then hydroxyl radicals will be generated ). have strong oxidation performance and can decompose organic matter to convert carbon, hydrogen and oxygen elements in organic matter into CO2, H2O and other substances, and organic carbon is mainly converted into CO2 gas, as shown in reactions 4-6.

[0117] (Reaction formula 4)

[0118] (Reaction formula 5)

[0119] (Reaction formula 6)

[0120] Directly adding H2O2 to the soil suspension can be directly converted into accelerate the conversion of organic carbon to CO2, shorten the reaction time, and improve the detection efficiency of soil organic carbon. Therefore, H2O2 is introduced in the ultraviolet light catalysis process, and the concentration of H2O2 is optimized, Figure 6 is the H2O2 concentration optimization result figure provided by the present application, as shown in Figure 6As shown, in the optimization process, the concentration of dissolved organic matter is fixed at 200 mg / L, and the photocatalytic reaction time is controlled at 10 minutes and 15 minutes. The results show that, with the increase of H2O2 concentration, the CO2 generation concentration first increases rapidly and then decreases slowly; when the H2O2 concentration is 500 mg / L, the CO2 generation concentration is the highest, so the H2O2 concentration is selected as 500 mg / L.

[0121] In some embodiments, the catalytic reaction time of ultraviolet light is 20 minutes.

[0122] Specifically, the catalytic reaction time of ultraviolet light affects the degree of decomposition of soil organic matter. If the time is too short, the soil organic matter may not be completely decomposed, and if the time is too long, the detection efficiency of soil organic matter will be reduced.

[0123] Therefore, Figure 7 is the optimization result graph of the photocatalytic reaction time of ultraviolet light provided by the present application. As Figure 7 shown, within 5-20 minutes, with the increase of reaction time, the CO2 generation concentration increases rapidly, and when the reaction time exceeds 20 minutes, the CO2 generation concentration remains basically unchanged, indicating that the decomposition of organic matter can be basically completed in 20 minutes of ultraviolet light catalysis. Therefore, the ultraviolet light catalytic reaction time is selected as 20 minutes for soil organic carbon detection.

[0124] In some embodiments, the second correction model is wherein, CO2 gas concentration is represented by C, and soil organic carbon content is represented by S.

[0125] Specifically, under the best photocatalytic conditions, different concentrations of dissolved organic matter are configured for ultraviolet light catalysis, the generated CO2 gas concentration is detected, and a correction model of organic carbon concentration and CO2 gas concentration is established.

[0126] Figure 8 is the correction model result graph between the organic carbon concentration and the CO2 gas concentration generated by ultraviolet light catalysis provided by the present application, as Figure 8 shown, the obtained second correction model is wherein, CO2 gas concentration is represented by C, and soil organic carbon content is represented by S. When the organic carbon concentration is in the range of 10-150 mg / L, the organic carbon concentration and the generated CO2 gas concentration have a good linear relationship ( =0.9938). The above results show that it is feasible to detect the generated CO2 gas concentration by ultraviolet light catalytic decomposition of organic matter, and then detect the organic carbon.

[0127] Figure 9is one of the process schematic diagrams of the soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection method provided by the present application, as shown in Figure 9 The present application provides a soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection method based on the soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen synchronous detection system described above, applied in the computer 50, which comprises the following steps:

[0128] Step 910, based on the CO2 gas background concentration in the environment, the first CO2 gas concentration after inorganic carbon acidolysis in the soil to be detected, the second CO2 gas concentration after organic carbon photolysis in the soil to be detected, the inorganic carbon content, the organic carbon content, the organic matter content, the total carbon content and the total nitrogen content in the soil to be detected are obtained.

[0129] Specifically, the computer 50 obtains the CO2 gas background concentration in the environment from the CO2 gas concentration detection module 30 , the first CO2 gas concentration after inorganic carbon acidolysis in the soil to be detected , and the second CO2 gas concentration after organic carbon photolysis in the soil to be detected .

[0130] The difference between the first CO2 gas concentration and the CO2 gas background concentration is the CO2 gas concentration produced by the decomposition of soil inorganic carbon in an acidic environment. The computer 50 obtains the inorganic carbon content in the soil to be detected according to the first CO2 gas concentration and the CO2 gas background concentration .

[0131] The difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration produced by the photolysis of organic carbon in the soil. The computer 50 obtains the organic carbon content in the soil to be detected according to the second CO2 gas concentration and the first CO2 gas concentration .

[0132] The computer 50 multiplies the organic carbon content in the soil to be detected by the correction coefficient (for example, 1.724) between soil organic carbon and soil organic matter to obtain the organic matter content in the soil to be detected. The computer 50 adds the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected to obtain the total carbon content in the soil to be detected.

[0133] The soil organic matter content and the soil total nitrogen content have strong correlation, and the computer 50 can obtain the total nitrogen content in the soil to be detected according to the soil organic matter content.

[0134] The application provides a synchronous detection method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen, which realizes rapid and selective detection of inorganic carbon by detecting the soil inorganic carbon content through the CO2 gas concentration after acidolysis of the soil inorganic carbon, realizes rapid on-site conversion of organic carbon by detecting the soil organic carbon content through the CO2 gas concentration after ultraviolet light / visible light catalysis of the soil organic carbon, calculates the soil organic matter content according to the correction coefficient of the soil organic matter and the soil organic carbon, avoids complex chemical extraction, obtains the soil total carbon according to the soil inorganic carbon and the soil organic carbon, and inverses the soil total nitrogen content according to the strong correlation between the soil total nitrogen and the soil organic matter, thereby saving the time-consuming steps of the traditional Kjeldahl method, and realizing rapid and synchronous detection of the soil organic matter, the soil inorganic carbon, the soil organic carbon, the soil total carbon and the soil total nitrogen in the field.

[0135] Figure 10 is a second flowchart of the synchronous detection method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the application, as shown in Figure 10 based on the CO2 gas background concentration in the environment, the first CO2 gas concentration after acidolysis of the inorganic carbon in the soil to be detected, the second CO2 gas concentration after photolysis of the organic carbon in the soil to be detected, the inorganic carbon content, the organic carbon content, the organic matter content, the total carbon content and the total nitrogen content in the soil to be detected are obtained, including the following steps:

[0136] In step 1010, the first CO2 gas concentration difference value is obtained according to the first CO2 gas concentration and the CO2 gas background concentration; and the inorganic carbon content in the soil to be detected is obtained according to the first CO2 gas concentration difference value and a first correction model of the CO2 gas concentration and the soil inorganic carbon.

[0137] Specifically, the difference value between the first CO2 gas concentration and the CO2 gas background concentration is the CO2 gas concentration produced by the decomposition of the soil inorganic carbon in the acidic environment, which is recorded as the first CO2 gas concentration difference value. The computer 50 pre-constructs the first correction model of the CO2 gas concentration and the soil inorganic carbon, and the first correction model is wherein, represents the CO2 gas concentration, and the soil inorganic carbon content. The computer 50 inputs the first CO2 gas concentration difference value into the first correction model to obtain the inorganic carbon content in the soil to be detected.

[0138] Step 1020, obtaining a second CO2 gas concentration difference value according to the second CO2 gas concentration and the first CO2 gas concentration; and obtaining the organic carbon content in the soil to be detected according to the second CO2 gas concentration difference value and a second correction model of CO2 gas concentration and soil organic carbon.

[0139] Specifically, the difference between the second CO2 gas concentration and the first CO2 gas concentration is the CO2 gas concentration generated by the photolysis of organic carbon in the soil, denoted as the second CO2 gas concentration difference value. The computer 50 pre-constructs a second correction model of CO2 gas concentration and soil organic carbon, and the second correction model is wherein, represents the CO2 gas concentration, and the soil organic carbon content. The computer 50 inputs the second CO2 gas concentration difference value into the second correction model to obtain the organic carbon content in the soil to be detected.

[0140] Step 1030, obtaining the organic matter content in the soil to be detected according to the organic carbon content in the soil to be detected and a correction coefficient between soil organic carbon and soil organic matter.

[0141] Specifically, the computer 50 multiplies the organic carbon content in the soil to be detected by the correction coefficient (for example, 1.724) between soil organic carbon and soil organic matter to obtain the organic matter content in the soil to be detected.

[0142] Step 1040, obtaining the total carbon content in the soil to be detected according to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected.

[0143] Specifically, the computer 50 adds the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected to obtain the total carbon content in the soil to be detected.

[0144] Step 1050, obtaining the total nitrogen content in the soil to be detected according to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, and a soil total nitrogen detection model; the soil total nitrogen detection model is a model taking soil inorganic carbon and soil organic carbon as input and taking soil total nitrogen as output.

[0145] Specifically, since the main component of total nitrogen in the soil is organic nitrogen, the soil organic matter content and the soil total nitrogen content have strong correlation. However, the correction coefficient between soil organic matter and soil total nitrogen is not fixed and will be affected by the soil type, and cannot be multiplied by a fixed correction coefficient like the correction coefficient between soil organic carbon and soil organic matter.

[0146] Considering that soil organic carbon has a strong correlation with soil total nitrogen, soil inorganic carbon has no correlation with soil total nitrogen, but soil inorganic carbon can reflect soil type information to a certain extent, therefore, a soil total nitrogen detection model is constructed by taking soil inorganic carbon and soil organic carbon as inputs and soil total nitrogen as output by means of a machine learning algorithm. Soil inorganic carbon is used to suppress the interference caused by soil type difference, so that the soil total nitrogen content can be detected more accurately. The machine learning algorithm includes but is not limited to partial least squares, support vector machine, random forest and the like.

[0147] The computer 50 inputs the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected into the soil total nitrogen detection model to obtain the total nitrogen content in the soil to be detected.

[0148] The synchronous detection method for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen provided by the application improves the detection accuracy of soil inorganic carbon by the first correction model, improves the detection accuracy of soil organic carbon by the second correction model, and further improves the detection accuracy of soil organic matter and soil total carbon, and the soil total nitrogen detection model is constructed by taking soil inorganic carbon and soil organic carbon as inputs and soil total nitrogen as output, so that the accuracy of soil total nitrogen detection is improved.

[0149] The following takes the computer 50 as a smart phone APP, the light source 40 as an ultraviolet photolysis lamp, and the CO2 gas concentration detection module 30 as TDLAS as an example for description. The specific detection steps are as follows:

[0150] (1) Collect farmland soil samples, dry the soil samples on a hot plate for 3 minutes, and weigh 0.5 g of dry soil samples by an electronic scale.

[0151] (2) Operate the smart phone APP to control the TDLAS and air pump 20 modules to work, detect the CO2 gas concentration in the environment, and record it as ; after the data is stable, stop the detection.

[0152] (3) Put the soil into the photolysis tank 10, add 40 mL of phosphate buffer and H2O2 with a concentration of 500 mg / L, then insert the ultraviolet photolysis lamp into the photolysis tank 10, and screw on the cover to seal.

[0153] (4) Operate the smart phone APP to control the air pump 20 module to work, blow air into the solution, and blow out the CO2 generated by the inorganic carbon acidolysis from the solution; after blowing air for 5 minutes, control the TDLAS to work to detect the CO2 gas concentration, record it as ; then control the TDLAS to stop detection.

[0154] (5) Operate the smartphone APP, turn on the ultraviolet photolysis lamp, start to decompose soil organic matter, and convert soil organic carbon into CO2. During the photolysis reaction process, the air pump 20 is always working to make the generated CO2 gas circulate. After 20 minutes of photolysis reaction, the TDLAS module is turned on to detect the CO2 gas concentration at this time, which is recorded as . Then, the smartphone APP is operated to control the air pump 20, photolysis lamp, and TDLAS to stop working.

[0155] (6) After this step, the lower computer hardware stops working, and the model operation function is completed on the smartphone APP. The difference is calculated. C 二氧化碳-无机碳 The difference is substituted into the first correction model to calculate the soil inorganic carbon content.

[0156] (7) The difference is calculated. C 二氧化碳-有机碳 The difference is substituted into the second correction model to calculate the soil organic carbon content.

[0157] (8) The soil organic carbon content is multiplied by 1.724 to obtain the soil organic matter content.

[0158] (9) The soil inorganic carbon content and the soil organic carbon content are input into the trained machine learning model to calculate the soil total nitrogen content.

[0159] (10) After detection, the soil suspension in the photolysis tank 10 is poured into the waste liquid tank for recovery, and the photolysis tank 10 is cleaned with deionized water, waiting for the next sample detection.

[0160] The following is an experiment using the system and method provided by the present application.

[0161] Two types of soil samples, brown soil in Beijing and black soil in northeast China, were collected for experimental verification. The detection results of the standard method were used as reference values. The detection accuracy of the method proposed in the present application was analyzed by plotting a scatter plot between the detection values and the reference values, calculating the and the root mean square error (RMSE) between the detection values and the reference values. The detection results of soil inorganic carbon (SIC), soil organic carbon (SOC), soil organic matter (SOM), soil total carbon (STC), and soil total nitrogen (STN) are shown in Figures 11-15 .

[0162] For soil inorganic carbon (SIC), Figure 11 is the detection result graph of soil inorganic carbon provided by the present application, and the detection result is shown in Figure 11 . After mixing the Beijing soil and the northeast soil (25 samples), the detection 0.8699, and the RMSE is 1.54 g / kg.

[0163] For soil organic carbon (SOC), Figure 12 is the detection result figure of soil organic carbon provided by the present application, and the detection result is as shown in the figure. Figure 12 The detection result of the mixed soil of Beijing and northeast soil (25 samples) is 0.8744, and the RMSE is 3.03 g / kg.

[0164] For soil organic matter (SOM), Figure 13 is the detection result figure of soil organic matter provided by the present application, and the detection result is as shown in the figure. Figure 13 Since SOM = SOC x 1.724, the detection result is equal to that of SOC, and the RMSE value is 1.724 times that of SOC. The detection RMSE of the mixed soil of Beijing and northeast soil (25 samples) is 5.22 g / kg.

[0165] For soil total carbon (STC), Figure 14 is the detection result figure of soil total carbon provided by the present application, and the detection result is as shown in the figure. Figure 14 The detection result of the mixed soil of Beijing and northeast soil (25 samples) is 0.9112, and the RMSE is 3.00 g / kg.

[0166] For soil total nitrogen (STN), Figure 15 is the detection result figure of soil total nitrogen provided by the present application, and the detection result is as shown in the figure. Figure 15 The detection result of the mixed soil of Beijing and northeast soil (25 samples) is 0.8542, and the RMSE is 0.295 g / kg.

[0167] In summary, the system and method provided by the present application have the detection values of SIC, SOC, SOM, STC and STN of the mixed soil samples of Beijing and northeast soil all higher than 0.8, which indicates that the method has high detection accuracy. Moreover, the developed system has the advantage of portability, and the time consumption is 25 minutes per sample. The system can be used for fast and synchronous detection of soil inorganic carbon, organic carbon, organic matter, total carbon and total nitrogen in the field.

[0168] ​​​​​It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A synchronous detection system for soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen, characterized in that, The application relates to a soil carbon and nitrogen detection device. The device comprises a gas pump, a photolysis tank and a CO2 gas concentration detection module which are sequentially connected in circulation, the photolysis tank contains soil suspension prepared by mixing soil to be detected and an acidic solution, the photolysis tank is provided with a light source, and the CO2 gas concentration detection module is in communication connection with a computer. Before detection, the CO2 gas concentration detection module detects the background concentration of CO2 gas in the environment. When the detection starts, the gas pump blows gas into the photolysis tank to blow the CO2 gas generated by the inorganic carbon in the soil to be detected into the CO2 gas concentration detection module, and the first CO2 gas concentration after the inorganic carbon in the soil to be detected is carbonated is detected. After the inorganic carbon in the soil to be detected is carbonated, the light source emits ultraviolet light or visible light to make the soil to be detected generate CO2 gas by organic carbon photolysis; the gas pump continues to blow gas into the photolysis tank to blow the CO2 gas generated by the organic carbon in the soil to be detected into the CO2 gas concentration detection module, and the second CO2 gas concentration after the organic carbon in the soil to be detected is photolyzed is detected. The computer is specifically used for: According to the first CO2 gas concentration difference and a first correction model of CO2 gas concentration and soil inorganic carbon, the inorganic carbon content in the soil to be detected is obtained. According to the second CO2 gas concentration difference and a second correction model of CO2 gas concentration and soil organic carbon, the organic carbon content in the soil to be detected is obtained. According to the organic carbon content in the soil to be detected and a correction coefficient between soil organic carbon and soil organic matter, the organic matter content in the soil to be detected is obtained. According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, the total carbon content in the soil to be detected is obtained. According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, and a soil total nitrogen detection model, the total nitrogen content in the soil to be detected is obtained; the soil total nitrogen detection model is a model taking soil inorganic carbon and soil organic carbon as input and taking soil total nitrogen as output. 2.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 1, wherein, The acidic solution is a phosphate buffer solution. 3.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 2, wherein, The solid-liquid ratio of the soil to be detected and the phosphate buffer solution is 1:

80. 4.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 1, wherein, When the inorganic carbon in the soil to be detected is carbonated, the blowing time of the gas pump is greater than or equal to 200 seconds. 5.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 1, wherein, When the light source is used to emit ultraviolet light, an oxidant type photolysis catalyst or a semiconductor photocatalyst is added into the soil suspension. 6.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 5, wherein, When the oxidant type photolysis catalyst is H2O2, the concentration of H2O2 is 500 mg / L.

7. The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 5, wherein, The catalytic reaction time of the ultraviolet light is 20 minutes. 8.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 1, wherein, When the light source is used to emit visible light, a semiconductor photocatalyst is added into the soil suspension. 9.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 1, wherein, The first correction model is wherein, represents the CO2 gas concentration, represents the soil inorganic carbon content. 10.The system for simultaneous determination of soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to claim 1, wherein, The second correction model is wherein, denotes the CO2 gas concentration, denotes the soil organic carbon content.

11. A method for simultaneously detecting soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen based on the system for simultaneously detecting soil inorganic carbon, soil organic carbon, soil organic matter, soil total carbon and soil total nitrogen according to any one of claims 1-10, characterized in that, The application relates to a soil carbon and nitrogen detection device. Based on the CO2 gas background concentration in the environment, the first CO2 gas concentration after inorganic carbon in the soil to be detected is decomposed, the second CO2 gas concentration after organic carbon in the soil to be detected is photolyzed, the inorganic carbon content, the organic carbon content, the organic matter content, the total carbon content and the total nitrogen content in the soil to be detected are obtained; The inorganic carbon content, the organic carbon content, the organic matter content, the total carbon content and the total nitrogen content in the soil to be detected are obtained based on the CO2 gas background concentration in the environment, the first CO2 gas concentration after inorganic carbon in the soil to be detected is decomposed, and the second CO2 gas concentration after organic carbon in the soil to be detected is photolyzed, including: According to the first CO2 gas concentration and the CO2 gas background concentration, a first CO2 gas concentration difference value is obtained; according to the first CO2 gas concentration difference value and a first correction model of CO2 gas concentration and soil inorganic carbon, the inorganic carbon content in the soil to be detected is obtained; According to the second CO2 gas concentration and the first CO2 gas concentration, a second CO2 gas concentration difference value is obtained; according to the second CO2 gas concentration difference value and a second correction model of CO2 gas concentration and soil organic carbon, the organic carbon content in the soil to be detected is obtained; According to the organic carbon content in the soil to be detected and a correction coefficient between soil organic carbon and soil organic matter, the organic matter content in the soil to be detected is obtained; According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, the total carbon content in the soil to be detected is obtained; According to the inorganic carbon content in the soil to be detected and the organic carbon content in the soil to be detected, and a soil total nitrogen detection model, the total nitrogen content in the soil to be detected is obtained; the soil total nitrogen detection model is a model taking soil inorganic carbon and soil organic carbon as input and taking soil total nitrogen as output.

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