Method and apparatus for determining nitrogen fertilizer diffusion in rice fields

Abstract

A method for measuring nitrogen fertilizer diffusion in a rice field, comprising: S10: preparing a soil sample; S20: placing the soil sample into a cavity of a container and flattening the soil sample, and burying nitrogen fertilizer in the soil sample during the process of placing the soil sample; S30: for each side edge of the cavity, injecting water into the cavity through a water injection port arranged within a range of 5 cm from a point on the side edge which is at the same height as an initial position of the nitrogen fertilizer; S40: allowing the soil sample to stand after the water injection; S50: freezing the soil sample after the standing; S60: cutting the frozen soil sample into a plurality of sample blocks; and S70: analyzing total nitrogen content of the sample blocks, and obtaining nitrogen fertilizer diffusion in the rice field according to the total nitrogen content of the sample blocks and positions of the sample blocks in the soil sample after the freezing. The method is suitable for measuring nitrogen fertilizer diffusion in a rice field. Furthermore, a device for measuring nitrogen fertilizer diffusion in a rice field for implementing the above method is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to a method and device for measuring nitrogen fertilizer diffusion in farmland, in particular to a method and device for measuring nitrogen fertilizer diffusion in paddy field. BACKGROUND

[0002] Nitrogen is one of the elements necessary for plant growth, and the nitrogen required for crop growth can be effectively supplemented by applying nitrogen fertilizer to farmland. Understanding the nitrogen fertilizer diffusion in farmland is conducive to precision fertilization, which can improve the utilization rate of nitrogen fertilizer. The existing method for measuring nitrogen fertilizer diffusion in farmland is mainly soil column method (Jiang Deai, Wang Yonghua, Tang Yida, Yang Jinsong, Zhang Hongye. Migration and accumulation of nitrogen compounds in soil and groundwater - dynamic study of nitrogen compounds in sewage entering soil [J]. Environmental Science, 1983 (03): 29-34. DOI: 10.13227 / j.hjkx.1983.03.008.). The soil column method uses simulated rainfall and irrigation, so it is suitable for dry land. In dry land, soil moisture is mainly affected by rainfall and irrigation, and the direction of soil water migration is mainly from top to bottom, and the nitrogen in the soil moves to the deep place. The paddy field in the south is plowed with a tractor under the condition of being filled with water, and the soil is soaked in water for a long time, and is broken and becomes a thin paste under the action of the tractor rotary tiller. After the nitrogen fertilizer is applied, the water in the soil is relatively stable, and the nitrogen fertilizer mainly migrates outward from the fertilization site by molecular diffusion. Therefore, the soil column method is not suitable for measuring the nitrogen fertilizer diffusion in the paddy field in the south. SUMMARY

[0003] The purpose of the present application is to provide a method for measuring nitrogen fertilizer diffusion in paddy field, which is suitable for measuring the nitrogen fertilizer diffusion in paddy field.

[0004] Another purpose of the present application is to provide a device for measuring nitrogen fertilizer diffusion in paddy field, which is conducive to conveniently measuring the nitrogen fertilizer diffusion in paddy field.

[0005] The present application provides a method for measuring nitrogen fertilizer diffusion in paddy field, which comprises:

[0006] S10: preparing a soil sample with the plough layer soil of the paddy field to be measured;

[0007] S20: taking a container, the container cavity is a prism with a rectangular bottom surface and is open on one side along the height direction to form an opening, the container does not leak after water is injected into the cavity, the container opening is placed upward, the soil sample is placed into the cavity and flattened, and the nitrogen fertilizer is buried in the soil sample at a set initial position during the process of placing the soil sample, the initial position corresponds to the midpoint of the bottom surface of the cavity along the height direction;

[0008] S30: for each side edge of the cavity, slowly inject water into the cavity through the water injection port arranged within a range of 5 cm from a point on the side edge which is at the same height as the initial position of the nitrogen fertilizer embedding, and keep the total water flow rate of the water injection port corresponding to each side edge constant at each moment during the water injection process, and stop the water injection when a water layer of 2-5 cm is formed on the surface of the soil sample;

[0009] S40: place the soil sample after water injection under a preset temperature condition and a preset humidity condition for a preset duration;

[0010] S50: freeze the soil sample after the placement;

[0011] S60: cut the frozen soil sample into a plurality of sample blocks along three sets of equidistant cutting surfaces, each set of equidistant cutting surfaces includes a plurality of parallel cutting surfaces, the three sets of equidistant cutting surfaces are parallel to the three mutually non-parallel surfaces of the cavity, the surface spacing of the three sets of equidistant cutting surfaces is equal, and the initial position of the nitrogen fertilizer embedding in the soil sample corresponds to one of the sample blocks; and

[0012] S70: analyze the total nitrogen content of the sample block, and obtain the nitrogen fertilizer diffusion condition in the rice field according to the total nitrogen content of the sample block and the position of the sample block in the soil sample after freezing.

[0013] The method for determining the nitrogen fertilizer diffusion in the rice field has a water injection mode which is beneficial to reducing the influence of the water flow on the nitrogen fertilizer diffusion; the soil sample is frozen to effectively retain the nitrogen components in the soil sample during the sample processing; the frozen soil sample is cut into sample blocks before detection, which is beneficial to improving the accuracy of the detection result. The method for determining the nitrogen fertilizer diffusion in the rice field simulates the rice field environment and is suitable for determining the nitrogen fertilizer diffusion condition in the rice field.

[0014] In another illustrative embodiment of the method for determining the nitrogen fertilizer diffusion in the rice field, the step S10 specifically comprises: first air-drying the tillage layer soil of the rice field to be determined, then crushing the soil, and then passing the soil through a 2 mm sieve to obtain the soil sample.

[0015] In still another illustrative embodiment of the method for determining the nitrogen fertilizer diffusion in the rice field, the container includes a box body and a plastic film laid on the entire inner surface of the box body around the cavity. The step S60 further comprises: before cutting the frozen soil sample, the frozen soil sample is taken out of the box body by pulling the plastic film.

[0016] In still another illustrative embodiment of the method for determining the nitrogen fertilizer diffusion in the rice field, the length of the bottom surface of the cavity is 26±2 cm or 32±2 cm, the width of the bottom surface of the cavity is 16±2 cm, the height of the soil sample after being placed in the cavity is 20-30 cm, and the total duration of the water injection is 3-5 hours.

[0017] In another exemplary embodiment of the method for determining nitrogen fertilizer diffusion in a rice field, in step S30, water is injected into the cavity through four water injection tubes inserted into the cavity. The four water injection tubes are connected to a water storage tank. The water storage tank is placed such that water in the water storage tank is injected into the cavity through the water injection tubes under the action of gravity.

[0018] In another exemplary embodiment of the method for determining nitrogen fertilizer diffusion in a rice field, in step S70, the sample block corresponding to the initial position of the nitrogen fertilizer buried in the soil sample is defined as the first sample block. The ratio of the difference between the total nitrogen content of the Nth sample block and the N+1th sample block to the total nitrogen content of the Nth sample block is less than a predetermined value, and the diffusion range of the nitrogen fertilizer in the direction along which the Nth sample block is located is determined to be (Nmin-2) x L, where Nmin is the minimum value of N and L is the distance between the cutting planes. The predetermined value is, for example, 5%.

[0019] The present application also provides a device for determining nitrogen fertilizer diffusion in a rice field, which is used to determine nitrogen fertilizer diffusion in a rice field by the above method, and comprises an experimental box. The experimental box has a receiving cavity. The receiving cavity is in the shape of a rectangular prism with an open side in the height direction to form an opening. The experimental box has four water injection channels. Each water injection channel has a water inlet and a water outlet. The water inlet is used to connect to a water source, and the water outlet is arranged on the inner surface of the experimental box facing the receiving cavity. For each side edge of the receiving cavity, the water outlet of a water injection channel is arranged within a range of 5 cm from a point on the side edge at the same height as the initial position of the nitrogen fertilizer buried in the soil sample. The device for determining nitrogen fertilizer diffusion in a rice field is easy to operate.

[0020] In another exemplary embodiment of the device for determining nitrogen fertilizer diffusion in a rice field, the experimental box comprises a bottom plate, four side plates, and a plurality of fasteners. The bottom plate is used to define the bottom surface of the receiving cavity. The four side plates are used to define the four side surfaces of the receiving cavity, respectively. Each side plate is hinged to the bottom plate. The hinge axis of each side plate is perpendicular to the height direction of the receiving cavity and parallel to the side surface of the receiving cavity defined by the side plate. The plurality of fasteners are used to fix the relative positions of the four side plates when the four side plates and the bottom plate enclose the receiving cavity.

[0021] In another exemplary embodiment of the device for determining nitrogen fertilizer diffusion in a rice field, the experimental box is provided with a raised pattern in the form of a square grid on the inner surface facing the receiving cavity. The longitudinal direction of the pattern is parallel to the height direction, and the transverse direction of the pattern is perpendicular to the height direction.

[0022] In another exemplary embodiment of the device for determining nitrogen fertilizer diffusion in a rice field, the device further comprises two laser lights. The two laser lights are arranged on the experimental box. The emitted light of the two laser lights can pass through the experimental box and enter the receiving cavity. The emitted light of the two laser lights is perpendicular to and intersects with two mutually perpendicular side surfaces of the receiving cavity, respectively. Attached Figure Description

[0023] The following figures are for illustrative purposes only and do not limit the scope of the invention.

[0024] Figure 1 This is a flowchart illustrating one embodiment of a method for measuring nitrogen fertilizer diffusion in paddy fields.

[0025] Figure 2 A schematic diagram illustrating a structural embodiment of an apparatus for measuring nitrogen fertilizer diffusion in paddy fields.

[0026] Figure 3 This is a schematic diagram illustrating the cutting location of a frozen soil sample.

[0027] Figure 4 This is a schematic diagram used to illustrate the determination of the diffusion range of nitrogen fertilizer.

[0028] Figure 5 This is a schematic diagram of another embodiment of a device for measuring nitrogen fertilizer diffusion in paddy fields.

[0029] Figure 6 for Figure 5 A partial cross-sectional view of the device shown.

[0030] Figure 7 for Figure 5 A schematic diagram of the device in its unfolded state.

[0031] Label Explanation

[0032] 10 containers

[0033] 11. Cavity

[0034] 13 Boxes

[0035] 14 Plastic film

[0036] 20 Water Injection Pipe

[0037] 30 Water Storage Tanks

[0038] 40 Experimental Box

[0039] 41 Receiving cavity

[0040] 43 Water Injection Channel

[0041] 431 water inlet

[0042] 432 Outlet

[0043] 44 Base Plate

[0044] 45 Side panels

[0045] 46 Ridges

[0046] 47 Hinge

[0047] 48 Fastener

[0048] 70 Laser light

[0049] 80 Frozen soil sample

[0050] 90 Sample block

[0051] H Height direction DETAILED DESCRIPTION

[0052] In order to make the technical features, objectives and effects of the application more clearly understood, the specific embodiments of the application will be described below with reference to the drawings, in which the same reference numerals represent the same or similar components having the same function.

[0053] In this document, "schematic" means "to serve as an example, instance, or illustration", and any illustration, embodiment described as "schematic" in this document should not be interpreted as a more preferred or more advantageous technical solution.

[0054] In this document, "rice field" refers to a paddy field in which rice is grown.

[0055] For the sake of simplicity, only the parts related to the application are shown in the drawings, which do not represent the actual structure of the product.

[0056] Figure 1 Flowchart of an exemplary embodiment of a method for determining nitrogen fertilizer diffusion in a rice field. As shown in FIG. 1, the method for determining nitrogen fertilizer diffusion in a rice field includes the following steps S10 to S70. Figure 1

[0057] S10: Prepare a soil sample from the plough layer soil of the rice field to be determined. Specifically, for example, the plough layer soil of the rice field to be determined is first air-dried, then crushed, and then passed through a 2 mm sieve to obtain the soil sample.

[0058] S20: As shown in FIG. 2, take a container 10, and the container cavity 11 of the container 10 is prismatic with a rectangular bottom surface and is open along one side (i.e., the upper side in FIG. 2) of the height direction H to form an opening. The length and width of the bottom surface of the container cavity 11 are, for example, equal to the row spacing and plant spacing of the rice planting, respectively, so as to simulate the smallest repeating unit of the rice field, analyze the complete nitrogen fertilizer diffusion of the rice field, and minimize the amount of soil used. The row spacing of the rice planting is, for example, 26±2 cm or 32±2 cm, and the plant spacing of the rice planting is, for example, 16±2 cm, but is not limited thereto. The depth of the container cavity 11 is, for example, 35 cm. Figure 2 Figure 2 ​​​

[0059] The container 10 does not leak after water is filled in the cavity 11. In the illustrative embodiment, the container 10 comprises a box 13 and a plastic film 14 laid on the entire inner surface of the box 13 around the cavity 11. The plastic film 14 can prevent water in the cavity 11 from leaking out. The plastic film 14 can extend 5-10 cm beyond the box 13, for example, where the height of the cavity 11 does not include the part of the plastic film 14 extending beyond the box 13. However, the embodiment is not limited to this, and in other illustrative embodiments, the plastic film 14 can not be provided if the box 13 itself can prevent water in the cavity 11 from leaking out.

[0060] The container 10 is placed with the opening upward, the soil sample is placed in the cavity 11 and leveled, and the nitrogen fertilizer is buried in the soil sample at a set initial position during the process of placing the soil sample, which corresponds to the midpoint of the bottom surface of the cavity 11 (i.e., the intersection of the diagonals of the rectangular bottom surface) in the height direction H. The initial position is 15 cm from the upper surface of the soil sample in the height direction H, for example, but the embodiment is not limited to this. The nitrogen fertilizer buried in the soil sample is 2.0-3.0 g, for example, which is pressed into a circular sheet with a diameter of 12-15 mm. Pressing the nitrogen fertilizer into a sheet can conveniently control the burial position of the nitrogen fertilizer.

[0061] S30: For each side edge of the cavity 11, slowly fill water into the cavity 11 through the water inlet provided within a range of not more than 5 cm from the point of the side edge at the same height as the initial position of the nitrogen fertilizer burial, and keep the total water flow rate of the water inlet corresponding to each side edge at each time constant during the water filling process. The water inlet corresponding to each side edge can be one or multiple. The water filling is stopped when a water layer of 2-5 cm is formed on the surface of the soil sample. Such a water filling method is conducive to reducing the influence of the water flow on the diffusion of the nitrogen fertilizer, and helps to improve the accuracy of the measurement.

[0062] In the illustrative embodiment, the length of the bottom surface of the cavity 11 is 26±2 cm or 32±2 cm, the width of the bottom surface of the cavity 11 is 16±2 cm, the height of the soil sample after being placed in the cavity 11 is 20-30 cm, and the total time of water filling is 3-5 hours. By controlling the speed of water filling, the influence of the water flow on the diffusion of the nitrogen fertilizer is reduced, which helps to improve the accuracy of the measurement.

[0063] Specifically, as Figure 2As shown, water is injected into the cavities 11, for example, by four water injection pipes 20 inserted into the cavities 11, each of the water injection pipes 20 corresponding to one side edge of the cavities 11. In the illustrative embodiment, the part of each of the water injection pipes 20 inserted into the cavities 11 is a hard pipe, and the upper part is a soft pipe, which is convenient for operation. The inner diameter of the hard pipe is, for example, 2±0.2 mm. The upper ends of the four water injection pipes 20 are connected to a water storage tank 30. The water storage tank 30 is placed so that the water in the water storage tank 30 can be injected into the cavities 11 through the water injection pipes 20 under the action of gravity. The water storage tank 30 is supported, for example, by a support (not shown in the figure). Figure 2 The four water injection pipes 20 need to be inserted into the cavities 11 before the soil sample is placed into the cavities 11, and the positions of the water injection pipes 20 are fixed under the action of the soil sample during the placement of the soil sample.

[0064] S40: The water-injected soil sample is left to stand under preset temperature conditions and preset humidity conditions for a preset time length. Specifically, for example, the water-injected soil sample is left to stand under temperature conditions of 25±2°C and humidity conditions of 60%-80% for 10-15 days, which are closer to the growth environment of rice. In other illustrative embodiments, the specific standing parameters can be adjusted as needed.

[0065] S50: The soil sample after standing is frozen. The specific method is, for example, placing the container 10 in an environment of -25±2°C for 2 days or pouring an appropriate amount of liquid nitrogen into the cavities 11.

[0066] S60: The frozen soil sample is cut into a plurality of sample blocks along three sets of equidistant cutting surfaces, each set of equidistant cutting surfaces including a plurality of parallel cutting surfaces, the three sets of equidistant cutting surfaces being parallel to the three mutually non-parallel faces of the cavities 11, and the face-to-face distances of the three sets of equidistant cutting surfaces being equal. The face-to-face distance of the equidistant cutting surfaces is, for example, 2 cm, but is not limited thereto. It can be understood that the shape of the cut sample block is a cube, and the edge length of the cube is equal to the face-to-face distance of the equidistant cutting surfaces. Figure 3 The cutting positions of the frozen soil sample are shown by dashed lines. The initial position of the nitrogen fertilizer buried in the soil sample corresponds to one of the sample blocks.

[0067] In the case where the container 10 is provided with the plastic film 14, the frozen soil sample can be taken out of the box 13 by pulling the plastic film 14 before cutting the frozen soil sample. The plastic film 14 can facilitate the taking out of the frozen soil sample from the box 13.

[0068] S70: The total nitrogen content of the sample blocks is analyzed, and the nitrogen fertilizer diffusion in the paddy field is obtained according to the total nitrogen content of the sample blocks and the positions of the sample blocks in the frozen soil sample. The method for analyzing the total nitrogen content of the sample blocks is, for example, “NY / T1121.24-2012 Soil Testing Part 24: Determination of Total Nitrogen in Soil Automatic Nitrogen Analyzer Method”. Specifically, see Figure 4For example, the sample block corresponding to the initial position of the nitrogen fertilizer buried in the soil sample is defined as the first sample block (S1) Figure 4 The numbers in the sample blocks represent the value of "X" in the "Xth sample block". If the difference between the total nitrogen content of the Nth sample block and the N+1th sample block, which is located outward from a face of the first sample block along the direction in which the face is oriented, and the total nitrogen content of the Nth sample block is less than a preset value (for example, 5%), the diffusion range of the nitrogen fertilizer along the direction in which the face is oriented is determined to be Nmin-2xL, where Nmin is the minimum value of N and L is the distance between the equidistant cutting faces. Thus, the diffusion ranges of the nitrogen fertilizer along the six directions can be obtained. Figure 4

[0069] The method for measuring the diffusion of nitrogen fertilizer in a rice field can inject water into the container through the water injection ports arranged within a range of 5 cm from the points on the side edges that are at the same height as the initial position of the nitrogen fertilizer buried in the soil sample. The total water flow rate of the water injection ports corresponding to each side edge at each time point is kept the same, so that the effects of the water flow from the four side edges on the diffusion of the nitrogen fertilizer can be offset, thereby reducing the influence of the water flow on the diffusion of the nitrogen fertilizer. In addition, the method for measuring the diffusion of nitrogen fertilizer in a rice field can effectively preserve the nitrogen components in the soil sample during the sample processing by freezing the soil sample. The soil sample is cut into sample blocks before detection, which can improve the accuracy of the detection results. The method for measuring the diffusion of nitrogen fertilizer in a rice field simulates the environment of a rice field and is suitable for measuring the diffusion of nitrogen fertilizer in a rice field.

[0070] The method described above can use the device shown in Figure 2 or the device shown in Figure 5 . Figure 5 FIG. 1 shows the structure of another exemplary embodiment of the device for measuring the diffusion of nitrogen fertilizer in a rice field. As shown in Figure 5 , the device for measuring the diffusion of nitrogen fertilizer in a rice field includes an experimental box 40, which functions as the container 10 in Figure 2 and is used to hold the soil sample. The experimental box 40 has a receiving cavity 41, which functions as the container cavity 11 in Figure 2 and is used to hold the soil sample. The receiving cavity 41 is in the shape of a prism with a rectangular bottom surface and is open on one side along the height direction H (i.e., the upper side in Figure 5 ) to form an opening. The length and width of the bottom surface of the receiving cavity 41 are, for example, equal to the row spacing and the plant spacing of the rice planting, respectively. The row spacing of the rice planting is, for example, 26±2 cm or 32±2 cm, and the plant spacing of the rice planting is, for example, 16±2 cm, but is not limited thereto. The depth of the container cavity 11 is, for example, 35 cm. The experimental box 40 includes a bottom plate 44 and four side plates 45. The bottom plate 44 is used to define the bottom surface of the receiving cavity 41. The four side plates 45 are used to define the four side surfaces of the receiving cavity 41, respectively.

[0071] ​Figure 6 for Figure 5 A partial cross-sectional view of the apparatus shown. The experimental chamber 40 has four water injection channels 43 ( Figure 6 Only two of the water injection channels 43 are visible in the image. The four water injection channels 43 function as follows: Figure 2 The four water inlet pipes 20 are used to inject water into the receiving cavity 41. Each water inlet channel 43 has an inlet 431 and an outlet 432. The inlet 431 is used to connect to a water source, which is connected, for example, via a flexible hose. Figure 2 The water storage tank 30 is shown. A water outlet 432 is located on the inner surface of the experimental chamber 40 facing the receiving cavity 41. For each side edge of the receiving cavity 41, a water outlet 432 of a water injection channel 43 is provided within a range of no more than 5 cm from a point at the same height as the initial position of nitrogen fertilizer burial (shown by the dotted line in the figure). Four water injection channels 43 are provided on the side plate 45. When using the device of this illustrative embodiment, it is not necessary to use... Figure 2 The plastic film 14 shown in the experimental chamber 40 can prevent water in the containment cavity 41 from leaking out (here, "leakage" refers to water migrating out of the containment cavity through the opening and water injection channel).

[0072] This device, used to measure nitrogen fertilizer diffusion in paddy fields, can be used to implement... Figure 1 The method shown is for measuring nitrogen fertilizer diffusion in paddy fields and is easy to operate.

[0073] like Figure 5 As shown, in the schematic embodiment, each side plate 45 is hinged to the base plate 44 via a hinge 47. The hinge axis of each side plate 45 is perpendicular to the height direction H of the receiving cavity 41 and parallel to the side surface of the receiving cavity 41 it defines. Figure 7 The image shows the state of the four side panels 45 of the experimental chamber 40 after they have been opened. (Example) Figure 5 As shown, the experimental chamber 40 also includes several fasteners 48. These fasteners 48 are used to secure the relative positions of the four side plates 45 when the four side plates 45 and the bottom plate 44 form the receiving cavity 41. The fasteners 48 may be, for example, self-locking latches for ease of operation, but are not limited to this. When it is necessary to remove the frozen soil sample from the experimental chamber 40, the four side plates 45 of the experimental chamber 40 can be opened first. Figure 7 As shown in the image, the frozen soil sample is then removed, which facilitates the operation.

[0074] like Figure 5 to Figure 7As shown in the schematic embodiment, the experimental chamber 40 has raised textures 46 in the shape of a square grid on its inner surface facing the receiving cavity 41, wherein the side length of the square is, for example, equal to the inter-face spacing of the equidistant cutting surfaces. The longitudinal direction of the textures 46 is parallel to the height direction H, and the transverse direction of the textures 46 is perpendicular to the height direction H. This results in a grid-like groove on the surface of the frozen soil sample corresponding to the textures 46, facilitating accurate determination of the cutting position during the cutting of the frozen soil sample.

[0075] like Figure 5 As shown in the schematic embodiment, the device also includes two laser lights 70. The two laser lights 70 are disposed on the outside of the experimental chamber 40. The emitted light beams of the two laser lights 70 can pass through the experimental chamber 40 and enter the receiving cavity 41. The experimental chamber 40 is made, for example, of a material that allows laser light to pass through. The emitted light beams of the two laser lights 70 are perpendicular to two mutually perpendicular sides of the receiving cavity 41 and intersect. In use, the emitted light beams of the two laser lights 70 can be aligned to the initial position of the nitrogen fertilizer burial in the soil sample. This allows for accurate positioning of the nitrogen fertilizer during the burial process, improving accuracy.

[0076] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0077] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent implementation schemes or modifications made without departing from the spirit of the present invention, such as combinations, divisions or repetitions of features, should be included within the scope of protection of the present invention.

Claims

1. A method for determining nitrogen fertilizer diffusion in paddy fields, characterized in that, An apparatus for measuring nitrogen fertilizer diffusion in paddy fields is used, the apparatus comprising: An experimental box (40) has a receiving cavity (41) which is a prism with a rectangular bottom and is open on one side along the height direction H to form an opening. The experimental box (40) has four water injection channels (43), each of the water injection channels (43) having a water inlet (431) and a water outlet (432). The water inlet (431) is used to connect to a water source, and the water outlet (432) is opened on the inner surface of the experimental box (40) facing the receiving cavity (41). For each side edge of the receiving cavity (41), a water outlet (432) of the water injection channel (43) is provided within a range of no more than 5 cm from the point at the same height as the initial position of nitrogen fertilizer burial on the side edge. The method includes: S10: Prepare soil samples using the topsoil layer of the paddy field to be tested; S20: Take one of the devices, which does not leak after water is injected into the receiving cavity. Place the opening of the device upward, put the soil sample into the receiving cavity and flatten it. During the process of putting the soil sample in, bury nitrogen fertilizer in the soil sample at a set initial position. The initial position corresponds to the midpoint of the bottom surface of the receiving cavity along the height direction. S30: For each side edge of the receiving cavity, water is injected into the receiving cavity through the water outlet. During the water injection process, the total water flow rate of the water outlet corresponding to each side edge is the same at each time. Water injection is stopped when a water layer of 2 cm to 5 cm is formed on the surface of the soil sample. S40: Allow the water-injected soil sample to stand for a preset time under preset temperature and humidity conditions; S50: Freeze the soil sample after it has been left to stand; S60: The frozen soil sample is cut into several sample blocks along three sets of equidistant cutting surfaces. Each set of equidistant cutting surfaces includes several parallel cutting surfaces. The three sets of equidistant cutting surfaces are parallel to three non-parallel surfaces of the receiving cavity, and the distance between the three sets of equidistant cutting surfaces is equal. The initial position of the nitrogen fertilizer buried in the soil sample corresponds to one of the sample blocks; and S70: Analyze the total nitrogen content of the sample block and obtain the nitrogen fertilizer diffusion in the paddy field based on the total nitrogen content of the sample block and the location of the sample block in the frozen soil sample.

2. The method for determining nitrogen fertilizer diffusion in paddy fields as described in claim 1, wherein, Step S10 specifically involves: first air-drying the topsoil of the paddy field to be tested, then crushing it, and finally passing it through a 2 mm sieve to obtain a soil sample.

3. The method for determining nitrogen fertilizer diffusion in paddy fields as described in claim 1, wherein, The length of the bottom surface of the receiving cavity is 26±2 cm or 32±2 cm, the width of the bottom surface of the receiving cavity is 16±2 cm, the height of the soil sample after being placed in the receiving cavity is 20 cm to 30 cm, and the total water injection time is 3 hours to 5 hours.

4. The method for determining nitrogen fertilizer diffusion in paddy fields as described in claim 1, wherein, In step S70, the sample block corresponding to the initial position of the nitrogen fertilizer buried in the soil sample is defined as the first sample block. The ratio of the difference in total nitrogen content between the Nth and N+1th sample blocks outward from one face of the first sample block along the direction of that face to the total nitrogen content of the Nth sample block is less than a preset value. The diffusion range of the nitrogen fertilizer along the direction of that face is determined to be (Nmin-2)×L, where Nmin is the minimum value of N and L is the inter-face distance of the equidistant cutting surfaces.

Images