Device for directly measuring the effects of roots and arbuscular mycorrhizal fungi on soil organic carbon dynamics

Abstract

The invention discloses a device for directly measuring the influence of roots and arbuscular mycorrhizal fungi on the dynamics of soil organic carbon, and relates to the technical field of soil ecology and microbial ecology experiments. The device comprises three separation tubes distributed at intervals in the circumferential direction and a filler supply assembly for supplying fillers to the separation tubes. The separation tubes are buried in the soil on one side of the roots and arbuscular mycorrhizal fungi to be measured. The separation tubes comprise: a bottom tube, which is buried in the soil; a top tube, which is fixedly connected to the top of the bottom tube, and at least one through groove is opened on the side of the top tube, and a ring is fixed on the inner wall of the top tube; a mesh tube, which is slidably fitted on the inner wall of the top tube and supported by the ring, and a mesh body is arranged on the side of the mesh tube, and the mesh body covers the through groove; a compactness adjustment tube, which is slidably fitted on the inner wall of the mesh tube and is used to cooperate with the bottom tube to receive the filler and adjust the compactness of the filler. The device can evaluate the influence of plant roots and arbuscular mycorrhizal fungi on the dynamics of soil organic carbon.

Description

Technical Field

[0001] The invention relates to the technical field of soil ecology and microbial ecology experiments, in particular to a device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon. Background Art

[0002] Most plant roots on land can form mutualistic symbiosis with arbuscular mycorrhizal fungi (AMF). Plant root residues, root and AMF exudates, and microbial residues are important sources of soil organic carbon (SOC). At the same time, AMF and their interactions with mycelial microorganisms play a key role in regulating the formation, transportation, and stabilization of SOC. In the context of climate change and human activities, the dynamic changes of SOC have an important impact on the global carbon cycle and climate change. Therefore, it is necessary to further clarify the mechanism of plant root-AMF symbiosis and mycelial microorganisms mediating the dynamics of SOC in order to better understand and manage soil carbon sequestration and respond to global climate change.

[0003] Therefore, it is necessary to provide a device for directly measuring the effects of roots and arbuscular mycorrhizal fungi on soil organic carbon dynamics to solve the above problems. Summary of the invention

[0004] In order to solve the above problems, the present invention provides the following technical solution: a device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon, comprising three separation tubes distributed at intervals in the circumferential direction and a filler supply assembly for supplying fillers to the separation tubes, wherein the separation tubes are buried in the soil on one side of the roots and arbuscular mycorrhizal fungi to be measured, and the separation tubes include:

[0005] a bottom pipe, which is buried in the soil;

[0006] A top pipe, which is fixedly connected to the top of the bottom pipe, and a side of the top pipe is provided with at least one through groove, an inner wall of the top pipe is fixed with a ring, and an upper surface of the ring is lower than the bottom of the through groove;

[0007] A net cylinder is slidably fitted on the inner wall of the top tube and supported by the ring. When the bottom of the net cylinder contacts the ring, the upper surface of the net cylinder is flush with the upper surface of the top tube. A net body is arranged on the side of the net cylinder, and the net body covers the through groove.

[0008] The compactness adjusting tube is slidably fitted on the inner wall of the mesh tube and is used to cooperate with the bottom tube to receive the filler and adjust the compactness of the filler. The side of the compactness adjusting tube has a plurality of evenly distributed side holes.

[0009] Preferably, the bottom of the top tube shrinks inwards and forms a shoulder for supporting the firmness adjustment tube;

[0010] A telescopic cylinder is fixed in the bottom tube, a base plate is fixed at the output end of the telescopic cylinder, a sealing plate is rotatably provided on the top of the base plate, and the sealing plate is sealingly and slidably connected with the compactness adjustment tube;

[0011] The top of the sealing disk is always in contact with the compactness adjustment tube.

[0012] Preferably, a plurality of spiral expansion tubes are embedded inside the compactness adjusting tube and are spaced apart along the axial direction of the compactness adjusting tube. Both ends of the spiral expansion tubes are closed. The plurality of spiral expansion tubes are connected to an air pipe, and the air pipe is connected to an external air control device.

[0013] Preferably, a plurality of axial expansion tubes are distributed inside the compactness adjusting tube, the axial expansion tubes extend axially along the compactness adjusting tube, and the plurality of axial expansion tubes together form a spiral shape, and both ends of the axial expansion tubes are closed and connected to the spiral expansion tube.

[0014] Preferably, when the compactness adjusting tube is used in conjunction with the bottom tube to adjust the compactness of the filler, the expansion degrees of the axial expansion tube and the spiral expansion tube are first adjusted using external gas control equipment, and then the telescopic cylinder is used to compact the filler upward, and finally the gas in the axial expansion tube and the spiral expansion tube is extracted.

[0015] Preferably, the filler supply assembly comprises:

[0016] A supply cylinder, on the inner wall of which a vibrating screen is fixed, on which natural C3 soil and natural C4 soil are pre-placed, and the supply cylinder is also pre-placed with quartz sand, which is located below the vibrating screen;

[0017] The stirring rod comprises a shaft body and blades arranged on the shaft body, wherein the shaft body slides through the vibration screen and is driven by a motor.

[0018] Preferably, at least one driven wheel is rotatably disposed in the supply cylinder, and the upper surface of the driven wheel is an inclined surface;

[0019] A vibration rod is vertically slidably arranged in the supply cylinder, the lower surface of the vibration rod contacts the upper surface of the driven wheel, the upper surface of the vibration rod contacts the lower surface of the deflection frame, one end of the deflection frame is hinged to the supply cylinder, and the other end is connected to the vibration screen by a return spring.

[0020] Preferably, a transmission wheel is fixed on the shaft body, and the transmission wheel is transmission-connected to the driven wheel.

[0021] Preferably, the pore sizes of the three meshes are 0.45 μm, 25 μm and 1800 μm respectively.

[0022] Preferably, a top cover is further provided on the upper portion of the top pipe;

[0023] The length of the jacking pipe is 0.15m-0.50m.

[0024] Compared with the prior art, the present invention provides a device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon, which has the following beneficial effects:

[0025] This device can be used to evaluate the contribution of plant roots and arbuscular mycorrhizal fungi to soil organic carbon, and it is highly targeted. Through meshes with different apertures, the effects of roots, arbuscular mycorrhizal fungi and mycelial microorganisms on soil organic carbon can be accurately distinguished. The device has a simple structure, is easy to operate, and is easy to install and disassemble.

[0026] In the present invention, through the expansion and exhaust process of the spiral expansion tube and the axial expansion tube, in cooperation with the bottom tube, the compaction degree of the filler can be precisely adjusted, thereby meeting the compaction requirements under different experimental conditions, and helping to more accurately simulate the dynamic changes of soil organic carbon under different soil conditions, thereby improving the reliability and accuracy of the experimental results.

[0027] In the filler supply assembly of the present invention, the design of fixing the driving wheel on the shaft and connecting it to the driven wheel not only improves the mixing efficiency and uniformity of the filler, but also makes the structure of the entire device more compact and the operation more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the main structure of the device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon;

[0029] Figure 2 Schematic diagram of the three-dimensional structure of the separation tube in the device for directly measuring the effects of roots and arbuscular mycorrhizal fungi on the dynamics of soil organic carbon;

[0030] Figure 3 Exploded view of the separation tube in the device for directly measuring the effects of roots and arbuscular mycorrhizal fungi on soil organic carbon dynamics;

[0031] Figure 4 Schematic diagram of the cross-sectional structure of the separation tube in the device for directly measuring the effects of roots and arbuscular mycorrhizal fungi on the dynamics of soil organic carbon;

[0032] Figure 5 Schematic diagram of the three-dimensional structure of the compaction regulating tube in the device for directly measuring the effects of roots and arbuscular mycorrhizal fungi on the dynamics of soil organic carbon;

[0033] Figure 6 for Figure 1 The enlarged structural diagram at A in the middle;

[0034] Figure 7 for Figure 3 The enlarged structural diagram at B in the middle;

[0035] Figure 8 Schematic diagram of the implementation of the device for directly measuring the effects of roots and arbuscular mycorrhizal fungi on soil organic carbon dynamics;

[0036] Fig. 9 It is a bar graph of the remaining percentage of organic carbon in different separation tubes;

[0037] Fig.10 It is a bar graph of the percentage of newly formed soil organic carbon in different separation tubes;

[0038] In the figure: 1. bottom tube; 2. top tube; 3. mesh tube; 4. compactness adjustment tube; 5. top cover; 6. filler supply assembly; 11. telescopic cylinder; 12. base plate; 13. sealing plate; 21. through groove; 22. ring; 23. shoulder; 31. mesh body; 41. axial expansion tube; 42. spiral expansion tube; 43. air pipe; 61. supply tube; 62. vibrating screen; 63. stirring rod; 64. transmission wheel; 65. driven wheel; 66. vibrating rod; 67. deflection frame; 68. reset spring. DETAILED DESCRIPTION

[0039] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned description of the drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, which is merely a way of distinguishing the objects of the same attributes when describing them in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0040] Example: Please refer to Figure 1-Figure 10 In an embodiment of the present invention, a device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon is provided, comprising three separation tubes spaced apart in the circumferential direction and a filler supply assembly 6 for supplying fillers to the separation tubes, wherein the separation tubes are buried in the soil on one side of the roots and arbuscular mycorrhizal fungi to be measured, and the separation tubes include:

[0041] A bottom pipe 1, which is buried in the soil;

[0042] A top pipe 2, which is fixedly connected to the top of the bottom pipe 1, and at least one through groove 21 is opened on the side of the top pipe 2, and a ring 22 is fixed on the inner wall of the top pipe 2, and the upper surface of the ring 22 is lower than the bottom of the through groove 21;

[0043] The net tube 3 is slidably fitted on the inner wall of the top tube 2 and supported by the ring 22. When the bottom of the net tube 3 contacts the ring 22, the upper surface of the net tube 3 is flush with the upper surface of the top tube 2. The side of the net tube 3 is provided with a net body 31, and the net body 31 covers the through groove 21.

[0044] The compactness adjusting tube 4 is slidably fitted to the inner wall of the mesh tube 3 and is used to cooperate with the bottom tube 1 to receive the filler and adjust the compactness of the filler. The side of the compactness adjusting tube 4 has a plurality of evenly distributed side holes.

[0045] The pore sizes of the three meshes 31 are 0.45 μm, 25 μm, and 1800 μm, respectively.

[0046] Among them, the formation of new organic carbon and the decomposition of old organic carbon can be calculated by the isotope mixing model; at the same time, the mesh 31 with a pore size of 0.45 μm can isolate the plant roots and the mycelium of arbuscular mycorrhizal fungi, but allow solutes to pass through, the mesh 31 with a pore size of 25 μm can isolate the plant roots but allow mycelium, microorganisms and solutes to pass through, and the mesh 31 with a pore size of 1800 μm allows plant roots, mycelium, microorganisms and solutes to pass through. Therefore, by comparing the organic carbon dynamics in meshes 31 with different pore sizes, the effects of roots and arbuscular mycorrhizal fungi and mycelial microorganisms on the dynamics of soil organic carbon can be evaluated.

[0047] Therefore, the implementation includes the following steps:

[0048] S1. The three separation tubes are buried in the soil on one side of the roots and arbuscular mycorrhizal fungi to be measured; ensuring that the pore size of the mesh body 31 of each separation tube 3 is 0.45 μm, 25 μm, and 1800 μm, respectively, to meet different separation requirements;

[0049] S2. Use the filler supply assembly 6 to inject filler into the compaction adjustment tube 4. The compaction adjustment tube 4 cooperates with the bottom tube 1 to receive the filler and adjust the compaction of the filler to simulate specific soil compaction conditions.

[0050] S3. Calculate the formation of new organic carbon and the decomposition of old organic carbon through isotope mixing models;

[0051] S4. Compare the dynamic changes of soil organic carbon in different separation tubes and evaluate the effects of root and arbuscular mycorrhizal fungi and hyphae microorganisms on soil organic carbon dynamics.

[0052] Specifically, refer to Fig. 9 and Fig.10 , Fig. 9 The bar graph shows the remaining percentage of organic carbon in different separation tubes. The results show that the growth of arbuscular mycorrhizal fungi promotes the decomposition of organic carbon, while root growth has no significant effect on the decomposition of organic carbon.

[0053] Fig.10 The bar graph shows the percentage of newly formed soil organic carbon in different separation tubes. The results show that the carbon derived from roots is significantly greater than the carbon derived from mycorrhizal fungi.

[0054] The soil type is black loess and loess soil developed on loess parent material, which is equivalent to ordinary calcareous soil (FAO classification system), with a total soil carbon content of 40.2 g kg -1 , total nitrogen is 4.0 g kg -1 , and the soil pH is around 8.0.

[0055] use 13 The C natural abundance method is used to evaluate the decomposition rate of soil organic matter. It is known that the vegetation in this area is all C3 plants. The leaves of the C4 plant Panicum virgatum were dried and cut into pieces (about 1 cm in length) as litter markers (Residue). To measure the organic carbon decomposition rate with the participation of roots and arbuscular mycorrhizal fungal hyphae, as well as without roots (but with arbuscular mycorrhizal fungal hyphae). In each test plot, a separation tube that does not allow roots or hyphae to enter and only allows some free-living microorganisms and ions to enter (hereinafter referred to as the control tube), a separation tube that allows hyphae to enter but not roots (hereinafter referred to as the hypha tube), and a separation tube that allows plant roots and hyphae to enter at the same time (hereinafter referred to as the root growth tube) are installed. These three separation tubes are covered with nylon membranes with pore sizes of 0.45μm, 25μm, and 1800μm, respectively. In addition, the material and specifications of the control tube are the same as those of the hypha tube and the root growth tube. The 0-10 cm soil collected from the plot was sieved (2 mm pore size) and mixed, and then mixed with yellow sand at a sand-to-soil ratio of 5:1. 200 g of the evenly mixed sand-soil mixture and 2.0 g of shredded switchgrass leaves were filled into the three separation tubes mentioned above. Construction of the C4 plant-C3 soil system (δ 13 C values ​​were approximately -13‰ and -24‰, respectively). In the experimental plot, a control tube, a mycelium tube and a root growth tube were randomly buried at a distance of at least 0.5 m from the edge, with the distance between the two tubes being at least 0.5 m.

[0056] use 13 The natural abundance method of C is used to evaluate the formation of organic carbon from roots and arbuscular mycorrhizal fungi. We put 200.0 g of soil from a corn field planted with C4 crops into the three types of separation tubes mentioned above. 13The C value was -14‰. The C3 plant was successfully constructed (root δ 13 C is -28‰)-C4 soil system and installed it into the soil of the field sample plot.

[0057] One year later, we retrieved the three types of separation tubes from the field plots. Using stable isotope techniques to determine the soil in the growth tubes 13 C abundance, and an isotope mixing model was used to calculate the decomposition rate of organic matter and the contribution of arbuscular mycorrhizal fungi and roots to SOC.

[0058] That is to say, the device is specially designed to measure the contribution of roots and arbuscular mycorrhizal fungi to soil organic carbon, and is highly targeted. Through the mesh 31 with different apertures, the influence of roots, arbuscular mycorrhizal fungi and mycelial microorganisms on soil organic carbon can be accurately distinguished. The device has a simple structure, convenient operation, and is easy to install and disassemble. The design of the filler supply component 6 and the compaction adjustment tube 4 makes the filler supply and compaction adjustment process more convenient.

[0059] In this embodiment, the bottom of the top tube 2 shrinks inwards and forms a clamping shoulder 23 for supporting the tightness adjustment tube 4;

[0060] A telescopic cylinder 11 is fixed in the bottom pipe 1, a base plate 12 is fixed at the output end of the telescopic cylinder 11, a sealing plate 13 is rotatably provided on the top of the base plate 12, and the sealing plate 13 is sealingly and slidably connected to the compactness adjustment tube 4;

[0061] The top of the sealing disk 13 is always in contact with the compactness adjusting tube 4 .

[0062] That is to say, the position of the output end of the telescopic cylinder 11 is defined so that the lowest position of the upper surface of the sealing disk 13 should be higher than or flush with the lower surface of the compaction adjustment tube 4, thereby preventing the filler from entering the bottom tube 1, wherein the telescopic cylinder 11 can be used to compact the filler upward.

[0063] Furthermore, a plurality of spiral expansion tubes 42 are embedded inside the compactness adjustment tube 4 and are distributed at intervals along the axial direction of the compactness adjustment tube 4. Both ends of the spiral expansion tubes 42 are closed. The plurality of spiral expansion tubes 42 are connected to an air pipe 43, and the air pipe 43 is connected to an external air control device.

[0064] In addition, a plurality of axial expansion tubes 41 are distributed inside the compactness adjustment tube 4. The axial expansion tubes 41 extend along the axial direction of the compactness adjustment tube 4, and the plurality of axial expansion tubes 41 together form a spiral shape. Both ends of the axial expansion tubes 41 are closed and connected to the spiral expansion tube 42.

[0065] Therefore, when the compactness adjusting tube 4 is used in conjunction with the bottom tube 1 to adjust the compactness of the filler, the expansion degrees of the axial expansion tube 41 and the spiral expansion tube 42 are first adjusted using an external gas control device, and then the telescopic cylinder 11 is used to compact the filler upward, and finally the gas in the axial expansion tube 41 and the spiral expansion tube 42 is extracted.

[0066] It should be noted that the mutual cooperation of the axial expansion tube 41 and the spiral expansion tube 42 can limit the packing in the axial and radial directions, and adjust the gaps between the packings. During implementation, the expansion and exhaust process of the spiral expansion tube 42 and the axial expansion tube 41 can achieve precise adjustment of the packing compactness. Specifically, first use an external gas control device to adjust the expansion degree of the axial expansion tube 41 and the spiral expansion tube 42, then use the telescopic cylinder 11 to compact the packing upward, and finally extract the gas in the axial expansion tube 41 and the spiral expansion tube 42. Among them, the expansion degree of the expansion tube (axial expansion tube 41, spiral expansion tube 42) can be precisely controlled by an external gas control device to meet the compactness requirements under different experimental conditions.

[0067] Precise adjustment of compaction can help to more accurately simulate the dynamic changes of soil organic carbon under different soil conditions, thereby improving the reliability and accuracy of experimental results.

[0068] In this embodiment, the filler supply assembly 6 includes:

[0069] A supply cylinder 61, on the inner wall of which a vibrating screen 62 is fixed, on which natural C3 soil and natural C4 soil are pre-placed, and quartz sand is also pre-placed in the supply cylinder 61, and the quartz sand is located below the vibrating screen 62;

[0070] The stirring rod 63 includes a shaft and blades arranged on the shaft. The shaft slides through the vibration screen 62 and is driven by a motor.

[0071] In addition, at least one driven wheel 65 is rotatably disposed in the supply cylinder 61, and the upper surface of the driven wheel 65 is an inclined surface;

[0072] A vibration rod 66 is vertically slidably arranged in the supply cylinder 61, the lower surface of the vibration rod 66 contacts the upper surface of the driven wheel 65, the upper surface of the vibration rod 66 contacts the lower surface of the deflection frame 67, one end of the deflection frame 67 is hinged to the supply cylinder 61, and the other end is connected to the vibration screen 62 by a return spring 68.

[0073] Of course, the filler supply assembly 6 also has a moving function, and the supply cylinder 61 has a function of controlling the discharge of materials, which will not be described in detail here.

[0074] Natural C3 soil and natural C4 soil are pre-placed on the vibrating screen 62 of the supply cylinder 61 to ensure that the two soils are evenly distributed. Quartz sand is pre-placed below the vibrating screen 62 as a supplementary component of the filler to adjust the physical properties of the filler.

[0075] During implementation, the motor is started to drive the shaft of the stirring rod 63 to rotate, and the blades on the shaft stir the soil and quartz sand falling from the vibrating screen 62. The driven wheel 65 in the supply cylinder 61 rotates, and its inclined surface contacts the lower surface of the vibrating rod 66, generating a vibration effect. The vibration of the vibrating rod 66 is transmitted to the vibrating screen 62 through the deflection frame 67, further promoting the screening efficiency.

[0076] That is, the filler is a mixture of sieved soil from long-term plantations of C3 plants (eg, wheat and soybeans) or C4 plants (eg, corn and switchgrass) and quartz sand.

[0077] Furthermore, a transmission wheel 64 is fixed on the shaft body, and the transmission wheel 64 is connected to the driven wheel 65 in transmission.

[0078] The synchronous operation of the stirring rod 63 and the vibrating rod 66 is achieved through the transmission connection between the driving wheel 64 and the driven wheel 65. This synchronous operation not only improves the mixing efficiency, but also makes the mixing of soil and quartz sand more uniform. In addition, the transmission design of the driving wheel 64 and the driven wheel 65 makes the structure of the entire filler supply assembly 6 more compact.

[0079] In this embodiment, a top cover 5 is further provided on the upper portion of the top pipe 2;

[0080] The length of the jacking pipe 2 is 0.15m-0.50m.

[0081] A top cover 5 is installed on the top of the top pipe 2 and its sealing is ensured to be good. During installation, the air pipe 43 passes through the top cover 5 .

[0082] According to the experimental requirements, the length of the top pipe 2 is adjusted within the range of 0.15m-0.50m.

[0083] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon, characterized in that: The invention comprises three separation tubes which are spaced apart in the circumferential direction and a filler supply assembly (6) for supplying filler to the separation tubes, wherein the separation tubes are buried in the soil on one side of the roots and arbuscular mycorrhizal fungi to be measured, and the separation tubes comprise: a bottom tube (1) which is buried in the soil; a top tube (2) which is fixedly connected to the top of the bottom tube (1), and at least one through groove (21) is formed on the side of the top tube (2), and a ring (22) is fixed on the inner wall of the top tube (2); and a net tube (3) which is slidably fitted on the top tube (2). ) and is supported by the ring member (22); a mesh body (31) is arranged on the side of the mesh cylinder (3), and the mesh body (31) covers the through groove (21); a compactness adjustment tube (4) is slidably fitted on the inner wall of the mesh cylinder (3) and is used to cooperate with the bottom tube (1) to receive the filler and adjust the compactness of the filler; the side of the compactness adjustment tube (4) has a plurality of evenly distributed side holes; the pore sizes of the mesh bodies (31) in the three separation tubes are 0.45 μm, 25 μm, and 1800 μm, respectively; Embedded inside the compactness adjustment tube (4) are a plurality of spiral expansion tubes (42) spaced apart along the axial direction of the compactness adjustment tube (4), both ends of the spiral expansion tube (42) are closed, the plurality of spiral expansion tubes (42) are connected to an air pipe (43), and the air pipe (43) is connected to an external air control device; A plurality of axial expansion tubes (41) are distributed inside the compactness adjustment tube (4), the axial expansion tubes (41) extending along the axial direction of the compactness adjustment tube (4), and the plurality of axial expansion tubes (41) together form a spiral shape, and both ends of the axial expansion tubes (41) are closed and communicate with the spiral expansion tube (42).

2. The device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon according to claim 1, characterized in that: The bottom of the top tube (2) is contracted inwardly and forms a shoulder (23) for supporting the compactness adjustment tube (4); a telescopic cylinder (11) is fixed in the bottom tube (1); a base plate (12) is fixed to the output end of the telescopic cylinder (11); a sealing plate (13) is rotatably provided on the top of the base plate (12); the sealing plate (13) is sealingly and slidably connected to the compactness adjustment tube (4); the top of the sealing plate (13) is always in contact with the compactness adjustment tube (4).

3. The device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon according to claim 2, characterized in that: When the compactness adjustment tube (4) is used in conjunction with the bottom tube (1) to adjust the compactness of the filler, the expansion degrees of the axial expansion tube (41) and the spiral expansion tube (42) are first adjusted using an external gas control device, and then the telescopic cylinder (11) is used to compact the filler upwards, and finally the gas in the axial expansion tube (41) and the spiral expansion tube (42) is extracted.

4. The device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon according to claim 1, characterized in that: The filler supply assembly (6) comprises: a supply cylinder (61) having a vibrating screen (62) fixed on its inner wall, natural C3 soil and natural C4 soil pre-placed on the vibrating screen (62), and quartz sand pre-placed in the supply cylinder (61), the quartz sand being located below the vibrating screen (62); and a stirring rod (63) comprising a shaft and blades arranged on the shaft, the shaft sliding through the vibrating screen (62) and being driven by a motor.

5. The device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon according to claim 4, characterized in that: At least one driven wheel (65) is rotatably arranged in the supply cylinder (61), and the upper surface of the driven wheel (65) is an inclined surface; a vibration rod (66) is vertically slidably arranged in the supply cylinder (61), the lower surface of the vibration rod (66) contacts the upper surface of the driven wheel (65), and the upper surface of the vibration rod (66) contacts the lower surface of a deflection frame (67); one end of the deflection frame (67) is hinged to the supply cylinder (61), and the other end is connected to the vibration screen (62) by a return spring (68).

6. The device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon according to claim 5, characterized in that: A transmission wheel (64) is also fixed on the shaft body, and the transmission wheel (64) is transmission-connected to the driven wheel (65).

7. The device for directly measuring the dynamic effects of roots and arbuscular mycorrhizal fungi on soil organic carbon according to claim 1, characterized in that: A top cover (5) is also provided on the upper part of the top pipe (2); the length of the top pipe (2) is 0.15m-0.50m.

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