Accuracy of measurement of ammonia volatilization in dryland by chamber method: field validation of simulation device and correction method

Abstract

The application discloses a kind of dry land ammonia volatilization box type method determination accuracy field verification simulation device, including circular sealing cover, the open end of cylindrical container and support grate, the circular sealing cover is matched with the open end of cylindrical container, the support grate diameter is matched with the inner diameter of cylindrical container, place in cylindrical container, a layer of quartz sand is placed on the support grate, and the cylindrical container is loaded with ammonium sulfate solution.It also discloses a correction method based on the above-mentioned dry land ammonia volatilization box type method determination accuracy field verification simulation device.Compared with the prior art, the application can more accurately simulate the actual situation of ammonia volatilization in dry land, and can be used with existing box-type device for measuring soil ammonia volatilization to further correct the error of existing box method for measuring ammonia volatilization in dry land. The determination result after correction can also better represent the ammonia volatilization in dry land under real natural environment.

Description

Technical Field

[0001] This invention relates to a field verification simulation device and calibration method for the accuracy of ammonia volatilization chamber method in dryland soil, belonging to the field of soil ammonia volatilization monitoring technology. Background Technology

[0002] Ammonia volatilization is a significant pathway for nitrogen fertilizer loss in farmland and a major source of ammonia in my country's atmosphere. The box sampling method is the primary method for determining ammonia volatilization in farmland. It calculates the ammonia volatilization rate by measuring the amount of ammonia volatilized from the soil within a covered area over a specific time period. It is simple to use, inexpensive, and allows for simultaneous measurements at multiple points, making it suitable for plot-based comparative experiments. However, the long-term or intermittent sealing of the sampling box alters the natural environment, leading to significant differences between the measured ammonia volatilization and the actual ammonia volatilization in the field. Secondly, ammonia is a chemically reactive gas and easily adheres to the inner wall of the sampling device, causing sampling errors. In plot-based comparative ammonia volatilization measurements, errors in the box sampling method can obscure differences in ammonia volatilization across different plots, severely affecting the scientific interpretation of the data. Without reliable error correction methods, it is also difficult to directly compare box sampling method data reported in different literature.

[0003] Currently, researchers often use ammonium bicarbonate solution for direct volatilization or ammonium sulfate solution with added weak alkali to prepare simulated ammonia volatilization sources to correct errors in the box method, achieving good results. However, while the simulated ammonia volatilization source prepared directly with ammonium-containing solution can effectively simulate the ammonia volatilization environment in paddy fields, it is difficult to represent the complex volatilization environment in dryland farmland. Because ammonia volatilization is significantly affected by meteorological factors, theoretically, ammonia volatilization in paddy fields is more susceptible to meteorological influences, while in dryland farmland, due to the barrier effect of soil particles, the degree of influence from meteorological factors is lower. Therefore, using simulated ammonia volatilization sources prepared directly with ammonium-containing solution to correct errors in the box method for measuring ammonia volatilization in dryland farmland will inevitably introduce some error. Summary of the Invention

[0004] To address the shortcomings of existing box-type method error correction devices and methods for determining ammonia volatilization in farmland, this invention provides a field verification simulation device and method for the accuracy of the box-type method for determining ammonia volatilization in dryland, which more accurately simulates the actual situation of ammonia volatilization in dryland farmland and precisely corrects the error of the box-type method for determining ammonia volatilization in dryland farmland.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A field verification simulation device for the accuracy determination of ammonia volatilization in dryland using a box-type method is characterized by comprising a circular sealing cap, a cylindrical container with one open end, and a supporting grate. The circular sealing cap matches the open end of the cylindrical container, and the diameter of the supporting grate matches the inner diameter of the cylindrical container. The supporting grate is placed inside the cylindrical container, and a layer of quartz sand is placed on the supporting grate. The cylindrical container contains an ammonium sulfate solution, which partially but not completely submerges the quartz sand. Regarding the liquid level of the ammonium sulfate solution: 1) If the ammonium sulfate solution completely submerges the quartz sand, the liquid level will inevitably be in direct contact with the external environment, which would cause the simulation device to lose its purpose of simulating the ammonia volatilization environment in dryland. 2) If the ammonium sulfate solution cannot contact the quartz sand, or if the solution is below the supporting grate, a water film may form on the mesh of the supporting grate due to surface tension, preventing the diffusion of volatilized ammonia gas from the lower layer of solution. Therefore, the ammonium sulfate solution needs to partially but not completely submerge the quartz sand.

[0007] Preferably, the support grate includes a circular mesh tray, support legs, and a handle. The support legs are located below the circular mesh tray and are used to support the circular mesh tray inside the cylindrical container. The handle is located above the circular mesh tray.

[0008] Preferably, the circular mesh, support legs, and handle are made of a hard material that does not react with ammonia, sulfuric acid, sodium carbonate, or sodium bicarbonate, typically metal or hard plastic.

[0009] Preferably, the particle size of the quartz sand is 2-3 mm, the height of the support grate from the bottom of the cylindrical container is 4-6 cm, a 4-6 cm thick layer of quartz sand is laid on the support grate, and the 2-3 cm thick layer of quartz sand is submerged by ammonium sulfate solution.

[0010] This invention also discloses a calibration method for a field verification simulation device based on the above-mentioned dryland ammonia volatilization box method for accuracy determination, the steps of which include:

[0011] A. Assemble n of the above-mentioned field verification simulation devices for determining the accuracy of the dryland ammonia volatilization box method. The ammonium sulfate solution in each simulation device is of equal volume. Add the same amount of sodium bicarbonate solution to each simulation device. Immediately tighten the sealing cap to prevent ammonia gas from spreading and shake well to ensure that the two solutions are fully mixed.

[0012] B. Dig n holes in the farmland with a diameter slightly larger than the outer diameter of the circular container of the simulation device, and put the simulation device into each hole. Place a box sampling box outside n / 2 of the simulation devices, and place the other n / 2 in the natural environment. Open the lids of all the simulation devices and immediately measure the ammonia volatilization rate of the simulation devices using the box method.

[0013] C. Once the ammonia volatilization loss rate of the simulation device reaches 65-75% under natural conditions, sampling should be stopped immediately. For samples collected by the recovery box method, a certain amount of sulfuric acid solution should be added to each simulation device to stop ammonia volatilization. After tightening the sealing cap, shake well and bring back to the laboratory. The ammonium ion content in the box method samples and the solution in the simulation device should be determined by the indophenol blue colorimetric method or a flow analyzer.

[0014] D. The ratio of the ammonia volatilization rate determined by the box method to the actual ammonia volatilization rate of the simulation device in the sampling box is used to characterize the accuracy of the box method in determining ammonia volatilization in dry farmland. The ratio of the ammonia volatilization rate determined by the box method to the actual ammonia volatilization rate of the simulation device under natural conditions is used to characterize the reliability of the box method results in representing ammonia volatilization under real natural conditions.

[0015] When this invention is used for calibration of a specific chamber method, the chamber method formula is used to calculate the ammonia volatilization rate determined by the chamber method.

[0016] Preferably, n in step A is an even number between 4 and 10, the simulation device contains 70 to 140 mg N / L ammonium sulfate solution, the volume of ammonium sulfate solution added is based on submerging 2 to 3 cm of quartz sand, and then 1 to 20 mL of 0.5 to 1 mol / L sodium bicarbonate solution is added, and 0.5 to 1 mol / L sulfuric acid is added in step C.

[0017] Preferably, the method for determining the ammonia volatilization loss rate of the simulated device under natural conditions to reach 65-75% in step C is as follows: Before conducting the calibration method experiment, the ammonia volatilization loss rate is tested through a pre-experiment. That is, based on the already determined concentrations of ammonium sulfate solution and sodium bicarbonate solution, 24 ammonia volatilization simulation devices are selected, and eight sodium bicarbonate solution addition amounts are set at 2.5, 5, 7.5, 10, 12.5, 15, 17.5, and 20 mL. Three simulation devices are set up for each addition amount. All devices are placed under natural conditions for volatilization. At the end of volatilization, an equal volume and concentration of sulfuric acid solution are added to each device. The range of sodium bicarbonate solution addition amount required to achieve an ammonia volatilization loss rate of 65-75% is determined under the set ammonia volatilization time.

[0018] The ammonia volatilization loss rate is set at 65-75% for the following reasons: 1) If the ammonia volatilization loss rate is too low, although the ammonia volatilization rate is fast, the difference in ammonia volatilization between the two environments cannot be accurately assessed. 2) As the ammonia volatilization loss rate increases, the ammonia volatilization rate gradually decreases due to the decrease in the concentration of the substrate (ammonium ions) for ammonia volatilization. If the ammonia volatilization loss rate is too high (e.g., 90%), the following situations may occur: the ammonia volatilization loss rate in the natural environment will approach 90% much earlier, but the ammonia volatilization rate in the box apparatus will be lower and will slowly reach 90%; when the ammonia volatilization rate in the natural environment reaches 70%, the loss rate in the box apparatus may only reach 35%, but when it reaches 90% in the natural environment, it may also reach 80% in the box apparatus. This is because the ammonia volatilization rate is slower in the natural environment, causing the difference in ammonia volatilization in the box apparatus to gradually narrow. Both excessively low and excessively high loss rates will cause the correction method of this invention to underestimate the difference between the ammonia volatilization rate determined by the box method and the ammonia volatilization in the natural environment. Therefore, by setting the ammonia volatilization loss rate to 65-75%, the accuracy of error correction using the correction method of this invention will be higher.

[0019] Preferably, the formula for calculating the ammonia volatilization rate Q in step D is as follows: Where C 始 C 终 V represents the concentration of ammonium sulfate solution in the simulation apparatus at the beginning and end of ammonia volatilization. 始 V 终 Let A be the volume of ammonium sulfate solution in the simulation device at the start and end of ammonia volatilization, A be the horizontal cross-sectional area of ​​the circular container in the simulation device, and t be the duration of ammonia volatilization in the simulation device. This formula is used to calculate both the actual ammonia volatilization rate in the sampling chamber and the actual ammonia volatilization rate in the simulation device under natural conditions.

[0020] The beneficial effects of this invention are:

[0021] Compared with existing technologies, this invention can more accurately simulate the actual situation of ammonia volatilization in dry farmland. It can be used in conjunction with existing box-type devices for measuring soil ammonia volatilization to further correct the errors of existing box-type methods for measuring ammonia volatilization in dry farmland. The corrected measurement results are more representative of ammonia volatilization in dry farmland under real natural conditions. Attached Figure Description

[0022] Figure 1 A schematic diagram of the ammonia volatilization simulation device for dryland in this invention is shown, without the addition of quartz sand and ammonium sulfate solution;

[0023] Figure 1 In the middle: 1 is a round, sealed plastic cap, 2 is a round plastic container, and 5 is a stainless steel support grate.

[0024] Figure 2A schematic diagram of the dryland ammonia volatilization simulation device of the present invention;

[0025] Figure 2 In the middle: 1 is a round sealed plastic cap, 2 is a round plastic container, 3 is quartz sand (dryland environment simulation layer), 4 is a mixed layer of quartz sand and ammonium sulfate solution (ammonia volatilization layer), 5 is a stainless steel support grate, 6 is ammonium sulfate solution (ammonia volatilization supply layer), 7 is a stainless steel handle, 8 is a stainless steel mesh tray, and 9 is a stainless steel support foot.

[0026] Figure 3 Schematic diagram of the field application of the present invention and the control device;

[0027] Figure 3 In the diagram: 10 is a dryland ammonia volatilization simulation device under natural conditions; 20 is a dryland ammonia volatilization simulation device of the present invention installed in an ammonia volatilization sampling box; 30 is a control ammonia volatilization simulation device under natural conditions; 40 is a control ammonia volatilization simulation device installed in an ammonia volatilization sampling box; 50 is an ammonia volatilization sampling box; and 60 is farmland soil.

[0028] Figure 4 Field application effects of this invention patent and control method;

[0029] Figure 4 In the diagram: a represents the recovery rate of the two box method tests conducted by the present invention patent and the control method; b represents the reliability of the results of the two box method tests conducted by the present invention patent and the control method in representing the true value of volatilization under natural conditions. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1:

[0032] 1. Experimental Design

[0033] This embodiment of the experiment was conducted in farmland within the Fengqiu National Field Scientific Observation and Research Station for Farmland Ecosystems, Chinese Academy of Sciences. This embodiment uses a traditional calibration method as a comparison to evaluate the effectiveness of two different methods for creating simulated volatile sources.

[0034] 1) Fabrication of the dryland ammonia volatilization simulation device of the present invention

[0035] First, nine circular containers 2, each 12cm in diameter and 11cm in inner wall height, and nine matching lids 1 are made. Simultaneously, nine sets of stainless steel support grates 5, each 10.5cm in total height, are fabricated. The cylindrical support legs 9 of each grate are 5cm high, the cylindrical handles 7 are 5.4cm high, and the stainless steel mesh trays 8 have 1mm mesh openings and an 11.9mm diameter. The stainless steel support grates are then placed into the circular containers, as shown below. Figure 1 As shown, place approximately 5 cm thick, 2-3 mm diameter quartz sand on each grate (wash and dry the quartz sand with distilled water before use). Number each ammonia volatilization simulation device in dryland areas and weigh each device (M1) using a 1 / 40 balance. Add 733 g of 140 mg N / L ammonium sulfate solution to each device by weighing. Figure 2 As shown, add 10 mL of 1 mol / L sodium bicarbonate solution, immediately tighten the sealed cap and shake well.

[0036] 2) Construction of a control ammonia volatilization simulation device

[0037] First, prepare nine circular containers, each 12 cm in diameter and 11 cm in inner wall height, along with nine matching lids. Number each ammonia volatilization simulation device and weigh each device (m1) using a 1 / 40 balance. Add 1100 g of 140 mg N / L ammonium sulfate solution and 15 mL of 1 mol / L sodium bicarbonate solution to each device by gravimetric analysis. Immediately tighten the lid and shake well.

[0038] 3) Field trials

[0039] Eighteen holes, each 10 cm deep and approximately 12.5–13 cm in diameter, were dug in the farmland. Six of these holes were each fitted with a static box-type sampling box 50 (see “Wang Chaohui et al. In-situ determination of soil ammonia volatilization in a winter wheat / summer maize rotation system in northern China. Acta Ecologica Sinica, 2002, Vol. 22, No. 3: 359-365”), and six of these holes were fitted with a vacuum box-type sampling box 50 (see “Ni Kang et al. Study on soil wheat quaternary ammonia volatilization loss and its influencing factors in a long-term fixed-location experiment of organic and inorganic fertilizers. Journal of Agricultural Environmental Science, 2009, Vol. 28, No. 12: 2614-2622”). The remaining six holes were left in the natural environment. All pits were divided into two groups, each group containing three pits each: one in a natural environment, one inside a static box sampling box, and one inside a vacuum box sampling box. One group placed a dryland ammonia volatilization simulation device 10 or 20 in each pit, while the other group placed a control ammonia volatilization simulation device 30 or 40 in each pit. Figure 3 As shown, open the covers of all devices and immediately collect volatile ammonia gas using the static box method and the vacuum box method respectively.

[0040] After 12 hours of continuous volatilization, ammonia samples were collected using the static chamber method and the vacuum chamber method. Simultaneously, 10 mL of 1 mol / L sulfuric acid solution was added to each dryland ammonia volatilization simulation device, and 15 mL of 1 mol / L sulfuric acid solution was added to each control ammonia volatilization simulation device. The sealing caps were then immediately tightened and the mixture was shaken well. All simulation devices were brought back to the laboratory, and the weights of each dryland ammonia volatilization simulation device (M2) and the control ammonia volatilization simulation device (m2) were weighed using a 1 / 4-pipe balance. The ammonium sulfate solution (NH4) in all devices was determined using the indophenol blue colorimetric method. + -N content, and the collection of NH4 by static box method and vacuum box method. + -N content.

[0041] 4) Ammonia volatilization calculation

[0042] The formula for calculating the ammonia volatilization rate Q in the ammonia volatilization simulation device in dryland is as follows: Where C 始 C 终 V represents the concentration of ammonium sulfate solution in the simulation apparatus at the beginning and end of ammonia volatilization. 始 V 终 Let V be the volume of ammonium sulfate solution in the simulation apparatus at the beginning and end of ammonia volatilization, A be the horizontal cross-sectional area of ​​the circular container in the simulation apparatus, and t be the duration of ammonia volatilization in the simulation apparatus. Here, the density of the ammonium sulfate solution is assumed to be 1 g / mL, then V... 始 =733mL, V 终 = (M2-M1)mL.

[0043] The formula for calculating the ammonia volatilization rate q in the ammonia volatilization simulation device is as follows: Where c 始 c 终 v represents the concentration of ammonium sulfate solution in the simulation apparatus at the beginning and end of ammonia volatilization. 始 v 终 Let v be the volume of ammonium sulfate solution in the simulation apparatus at the beginning and end of ammonia volatilization, 'a' be the horizontal cross-sectional area of ​​the circular container in the simulation apparatus, and 't' be the duration of ammonia volatilization in the simulation apparatus. Here, the density of the ammonium sulfate solution is assumed to be 1 g / mL. 始 =1100mL, v 终 = (m2-m1)mL.

[0044] The ratio of the ammonia volatilization rate determined by the vacuum chamber method to the actual ammonia volatilization rate in the simulated device within the vacuum chamber sampling chamber indicates the accuracy (recovery rate) of the vacuum chamber method. Similarly, the ratio of the ammonia volatilization rate determined by the static chamber method to the actual ammonia volatilization rate in the simulated device within the static chamber sampling chamber indicates the accuracy (recovery rate) of the static chamber method. Likewise, the ratio of the ammonia volatilization rate determined by the vacuum chamber method to the ammonia volatilization rate in a simulated device under natural conditions indicates the reliability of the vacuum chamber method's results in representing the true value of ammonia volatilization under natural conditions, and the ratio of the static chamber method's results in representing the true value of ammonia volatilization under natural conditions indicates the reliability of the static chamber method's results in representing the true value of ammonia volatilization under natural conditions.

[0045] 2. Test Results

[0046] like Figure 4 As shown in Figure a, the dryland ammonia volatilization simulation device and application method described in this invention were used to test two commonly used box-type methods in China. The results showed that the accuracy of the vacuum chamber method was 81%, and the accuracy of the static box-type method was 91%. However, when a control simulation device and method were used, the results showed that the accuracy of the vacuum chamber method and the static box-type method were 91% and 99%, respectively. The accuracy of the box-type method tested was significantly higher than that of this invention. Therefore, it is evident that using traditional simulation devices significantly overestimates the accuracy of the box-type method in determining ammonia volatilization in dryland farmland. Consequently, correcting the ammonia volatilization rate measured by the box-type method significantly overestimates ammonia volatilization losses. Compared to ammonia volatilization under natural conditions, the test results of this invention show that the vacuum chamber method significantly underestimates ammonia volatilization losses in dryland farmland, while the control simulation device shows that the results of the vacuum chamber method are less different from those in the natural environment. In other words, the control method overestimates the reliability of the vacuum chamber method's results in representing ammonia volatilization in dryland farmland under natural conditions. Figure 4 b). The ratio of the static box method test results from this invention patent and the control simulation device to those from ammonia volatilization in the natural environment is very small, meaning that the results of the two methods for testing the static box method are basically consistent in representing the reliability of ammonia volatilization in dry farmland under natural conditions. Figure 4 b).

[0047] In summary, compared with traditional ammonia volatilization simulation devices and application methods, this invention can more accurately simulate the actual situation of ammonia volatilization in dry farmland, more precisely correct the error of the box method for measuring ammonia volatilization in dry farmland, and the corrected measurement results can better represent ammonia volatilization in dry farmland under real natural conditions, proving the advanced nature and effectiveness of this invention patent.

Claims

1. A field verification simulation device for the accuracy determination of ammonia volatilization chamber method in dryland areas, characterized in that: The device includes a circular sealing cap, a cylindrical container with one open end, and a support grate. The circular sealing cap matches the open end of the cylindrical container, and the diameter of the support grate matches the inner diameter of the cylindrical container. The support grate is placed inside the cylindrical container, and a layer of quartz sand is placed on the support grate. The cylindrical container is filled with an ammonium sulfate solution, which partially but not completely submerges the quartz sand. The calibration method for the field verification simulation device for the accuracy determination of ammonia volatilization chamber method in dryland is as follows: A. Assemble n field verification simulation devices for the accuracy determination of ammonia volatilization box method in dry land. The ammonium sulfate solution in each simulation device is of equal volume. Add the same amount of sodium bicarbonate solution to each simulation device. Immediately tighten the sealing cap to prevent ammonia gas from spreading and shake well to mix the two solutions thoroughly. B. Dig n holes in the farmland with a diameter slightly larger than the outer diameter of the circular container of the simulation device, and put the simulation device into each hole. Place a box sampling box outside n / 2 of the simulation devices, and place the other n / 2 in the natural environment. Open the lids of all the simulation devices and immediately measure the ammonia volatilization rate of the simulation devices using the box method. C. Once the ammonia volatilization loss rate of the simulation device reaches 65-75% under natural conditions, sampling should be stopped immediately. For the recovered box-type sample, a certain amount of sulfuric acid solution should be added to each simulation device, the sealed cap should be tightened, and the sample should be shaken well and brought back to the laboratory. The ammonium ion content in the box-type sample and the solution in the simulation device should be determined by the indophenol blue colorimetric method or a flow analyzer. D. The ratio of the ammonia volatilization rate determined by the box method to the actual ammonia volatilization rate of the simulation device in the sampling box is used to characterize the accuracy of the box method in determining ammonia volatilization in dry farmland. The ratio of the ammonia volatilization rate determined by the box method to the actual ammonia volatilization rate of the simulation device under natural conditions is used to characterize the reliability of the box method results in representing ammonia volatilization under real natural conditions.

2. The field verification simulation device for the accuracy determination of ammonia volatilization chamber method in dryland areas according to claim 1, characterized in that: The support grate includes a circular mesh tray, support legs, and a handle. The support legs are located below the circular mesh tray and are used to support the circular mesh tray inside the cylindrical container. The handle is located above the circular mesh tray.

3. The field verification simulation device for the accuracy determination of ammonia volatilization chamber method in dryland areas according to claim 2, characterized in that: The circular mesh, support legs, and handle are made of metal or rigid plastic.

4. The field verification simulation device for the accuracy determination of ammonia volatilization chamber method in dryland areas according to claim 1, characterized in that: The quartz sand has a particle size of 2-3 mm, the support grate is 4-6 cm high from the bottom of the cylindrical container, a 4-6 cm thick layer of quartz sand is laid on the support grate, and the ammonium sulfate solution submerges the 2-3 cm thick layer of quartz sand.

5. A calibration method for a field verification simulation device for the accuracy determination of ammonia volatilization chamber method in dryland, based on any one of claims 1-4, characterized in that... The steps include: A. Assemble n field verification simulation devices for determining the accuracy of the dryland ammonia volatilization box method as described in any of claims 1-4. The ammonium sulfate solution in each simulation device is of equal volume. Add the same amount of sodium bicarbonate solution to each simulation device. Immediately tighten the sealing cap to prevent ammonia gas from diffusing. Shake well to mix the two solutions thoroughly. B. Dig n holes in the farmland with a diameter slightly larger than the outer diameter of the circular container of the simulation device, and put the simulation device into each hole. Place a box sampling box outside n / 2 of the simulation devices, and place the other n / 2 in the natural environment. Open the lids of all the simulation devices and immediately measure the ammonia volatilization rate of the simulation devices using the box method. C. Once the ammonia volatilization loss rate of the simulation device reaches 65-75% under natural conditions, sampling should be stopped immediately. For the recovered box-type sample, a certain amount of sulfuric acid solution should be added to each simulation device, the sealed cap should be tightened, and the sample should be shaken well and brought back to the laboratory. The ammonium ion content in the box-type sample and the solution in the simulation device should be determined by the indophenol blue colorimetric method or a flow analyzer. D. The ratio of the ammonia volatilization rate determined by the box method to the actual ammonia volatilization rate of the simulation device in the sampling box is used to characterize the accuracy of the box method in determining ammonia volatilization in dry farmland. The ratio of the ammonia volatilization rate determined by the box method to the actual ammonia volatilization rate of the simulation device under natural conditions is used to characterize the reliability of the box method results in representing ammonia volatilization under real natural conditions.

6. The correction method according to claim 5, characterized in that: In step A, n is an even number between 4 and 10. The simulation device contains 70-140 mg N / L ammonium sulfate solution. The volume of ammonium sulfate solution added is sufficient to submerge 2-3 cm of quartz sand. Then, 1-20 mL of 0.5-1 mol / L sodium bicarbonate solution is added. In step C, 0.5-1 mol / L sulfuric acid is added.

7. The correction method according to claim 5, characterized in that: The method for determining the ammonia volatilization loss rate of the simulated device under natural conditions to reach 65-75% in step C is as follows: Before conducting the calibration method experiment, the ammonia volatilization loss rate is tested through a pre-experiment. That is, based on the already determined concentrations of ammonium sulfate solution and sodium bicarbonate solution, 24 ammonia volatilization simulation devices are selected, and eight sodium bicarbonate solution addition amounts are set at 2.5, 5, 7.5, 10, 12.5, 15, 17.5, and 20 mL. Three simulation devices are set up for each addition amount. All devices are placed under natural conditions for volatilization. At the end of volatilization, an equal volume and concentration of sulfuric acid solution are added to each device. Under the set ammonia volatilization time, the range of sodium bicarbonate solution addition amounts required to achieve an ammonia volatilization loss rate of 65-75% is determined.

8. The correction method according to claim 5, characterized in that: The ammonia volatilization rate of the simulation device in step D Q The calculation formula is C 始 C 终 V represents the concentration of ammonium sulfate solution in the simulation apparatus at the beginning and end of ammonia volatilization. 始 V 终 Let A be the volume of ammonium sulfate solution in the simulation device at the beginning and end of ammonia volatilization, A be the horizontal cross-sectional area of ​​the circular container in the simulation device, and t be the duration of ammonia volatilization in the simulation device.

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