A sampling device for adjustable aeration ammonia volatilization in wheat field

Abstract

The utility model provides a kind of adjustable ventilation ammonia volatilization sampling device of wheat field, belong to sampling device technical field, the adjustable ventilation ammonia volatilization sampling device of this wheat field includes: coaxial sleeve and axially opposite sliding outer ventilation chamber and inner ventilation chamber;Elastic clamping tongue is protruded in the inner ventilation chamber outer wall along radial, and a plurality of clamping slots are arranged on the outer ventilation chamber wall surface along axial interval;Positioning table is respectively fixed on the inner wall upper portion and lower portion of the inner ventilation chamber;Transparent rain cover is covered in the top of the outer ventilation chamber and inner ventilation chamber, and the outer edge of the rain cover extends downward to form apron;At least two telescopic rods can be axially telescopic, the telescopic rod includes first support rod and second support rod in sequence from top to bottom, and the upper end of the first support rod is detachably connected with the apron, solves the problem that existing fixed-height ventilation method device cannot be elongated in situ with the increase of wheat plant, leading to the problem that continuous trapping ammonia volatilization after topdressing, data interruption cannot be achieved in high stem stage.

Description

Technical Field

[0001] This utility model belongs to the field of sampling device technology, specifically, it relates to an adjustable ventilation ammonia volatilization sampling device for wheat fields. Background Technology

[0002] In dryland wheat systems, ammonia volatilization peaks often occur within a week after surface application of nitrogen fertilizer. Accurately capturing ammonia flux during this period is a prerequisite for assessing fertilizer efficiency loss and developing emission reduction strategies. The aeration method, due to its simple structure and lack of electricity, is widely used for in-situ field sampling: a cylindrical section is vertically pressed into the soil, with two layers of acid-soaked sponges suspended inside. Ammonia released from the soil rises naturally via convection and is captured by the lower sponge, while the upper sponge blocks external ammonia interference. The volatilization flux can be inverted by measuring the increase in acid concentration. However, with the development of cultivation patterns towards dense planting, tall stalks, and delayed nitrogen application, the traditional combination of "fixed-length cylinder + single-layer rainproof cover" has gradually revealed its disconnect from agronomic rhythms. First, the cylinder length is designed based on seedling height; after the jointing stage, the wheat top rapidly exceeds the cylinder opening, and continued sampling will truncate the plant and disrupt the canopy microenvironment, leading to data distortion. If a taller cylinder is used, the original sampling points need to be redone, disrupting the time series. Secondly, the cylindrical top cover is often a simple flat plate, which easily forms water flow along the wall during windy and rainy weather. The water film falls straight down the inner wall to the lower sponge, diluting the acid solution and drastically reducing its absorption capacity, thus systematically underestimating the volatility peak. Furthermore, the sponge is suspended only by friction against the cylinder wall; it easily slides down or even falls off after being touched by livestock in the field, swayed by strong winds, or soaked by rainwater, making sample representativeness impossible. In addition, the fixed-height support cannot extend synchronously with the increase in cylinder height, rendering the top rain-proof structure meaningless. Operators are often forced to perform "rescue" sampling during breaks in wind and rain, resulting in high labor intensity and poor data integrity. Utility Model Content

[0003] In view of this, the present invention provides an adjustable ventilation ammonia volatilization sampling device for wheat fields, which solves the problem that existing fixed-height ventilation devices cannot extend in situ as the wheat plants grow taller, resulting in the inability to continuously capture ammonia volatilization and data interruption during the tall stalk stage after topdressing.

[0004] This utility model is implemented as follows:

[0005] This utility model provides an adjustable aeration ammonia volatilization sampling device for wheat fields, comprising:

[0006] An outer ventilation chamber and an inner ventilation chamber are coaxially fitted and can slide relative to each other axially. Both the outer ventilation chamber and the inner ventilation chamber are cylindrical bodies with open ends.

[0007] An elastic latch protrudes radially from the outer wall of the inner ventilator and a plurality of slots are spaced axially on the outer ventilator wall. The elastic latch can engage with any slot to position the two ventilators at the required axial length.

[0008] Positioning platforms are respectively fixed to the upper and lower parts of the inner ventilation chamber wall, and the upper end surface of each positioning platform is used to horizontally support the absorbent sponge impregnated with acid.

[0009] A transparent rain cover is installed on the top of the outer and inner ventilation chambers, and the outer edge of the rain cover extends downward to form a skirt, which surrounds the upper periphery of the two ventilation chambers.

[0010] At least two axially extendable telescopic rods, the telescopic rods including a first support rod and a second support rod from top to bottom, the upper end of the first support rod being detachably connected to the skirt, and the lower end of the second support rod being provided with a pointed conical guide head, the guide head being used to insert into the soil to vertically fix the rain cover and the two ventilation chambers.

[0011] The technical effects of the adjustable ventilation ammonia volatilization sampling device for wheat fields provided by this utility model are as follows: Through the three-dimensional combination of this utility model, the sampling channel can be extended immediately as the wheat plants grow taller after being inserted into the wheat field once. The rain cover and telescopic rod together form an integrated support of "umbrella rib-umbrella handle", which not only prevents rainwater from falling in but also avoids crosswinds from disturbing the airflow, ensuring that the ammonia volatilization capture space is always vertical, unobstructed and height adjustable. This solves the defects of traditional fixed-length PVC pipes that cannot be adapted to the increased plant height after topdressing, are prone to water ingress in rainy weather, and are easily blown off by the sponge, greatly improving the efficiency of field sampling and data continuity.

[0012] Based on the above technical solution, the adjustable aeration ammonia volatilization sampling device for wheat fields of this utility model can be further improved as follows:

[0013] The length of the fitting section between the outer ventilator and the inner ventilator is not less than two-thirds of the total length of the inner ventilator, so as to ensure coaxial stability throughout the telescopic process.

[0014] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the length of the fitting section is not less than two-thirds of the total length of the inner ventilation chamber, so that the inner and outer cylinders still retain sufficient overlapping guide sections at any extension position, forming a "long guide rail" effect, avoiding swaying with the wind or eccentric jamming, ensuring that the whole remains vertical and continuous after extension and contraction, reducing the airflow dead zone caused by tilting, improving the representativeness of ammonia capture, and at the same time reducing the risk of fatigue fracture of the tongue under bending moment, extending the reuse cycle in the field.

[0015] Furthermore, the elastic latch is a rubber stopper with a hemispherical free end. The diameter of the hemisphere is slightly larger than the width of the slot opening, so that elastic damping is generated after engagement.

[0016] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the hemispherical rubber stopper acts as an elastic latch, and its diameter is slightly larger than the opening of the slot. When it is inserted, it first deforms elastically and then rebounds to reset, forming a self-locking feel. The height can be adjusted with one hand without tools. The hemispherical surface contacts the arc surface of the slot, resulting in low friction but high release force. This prevents slippage and allows for pull-up unlocking, balancing convenient operation and reliable positioning, and is suitable for field work environments where gloves are worn.

[0017] Furthermore, the positioning platform includes a first positioning block and a second positioning block from top to bottom. The first positioning block is fixed on both sides of the top of the inner ventilation chamber, and the second positioning block is fixed on both sides of the bottom of the inner ventilation chamber. The positioning platform is equidistantly distributed along the circumference of the inner ventilation chamber. The radial width of the positioning platform is less than the thickness of the absorbent sponge, so that the absorbent sponge is radially limited while its upper surface is exposed to the airflow.

[0018] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the first and second positioning blocks are circumferentially equidistant and restrict the radial movement of the absorbent sponge, so that the two sponges are always parallel vertically and suspended in the inner ventilation chamber, avoiding ammonia loss caused by "short-circuit airflow" caused by the gaps in the cylinder wall; the thickness of the positioning block is less than the thickness of the sponge, ensuring that the top surface of the sponge is completely facing the airflow, and the bottom surface can also fully exchange gases with the soil volatile surface through the gaps, thereby improving the absorption efficiency per unit time and eliminating the test error caused by the skewness of the sponge.

[0019] Furthermore, the lower end face of the skirt of the rain cover is lower than the upper end face of the two ventilation chambers, forming a shielding gap to prevent lateral rainwater from entering the ventilation chamber.

[0020] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the lower end face of the skirt is lower than the upper end face of the ventilation chamber to form a shielding gap, which is equivalent to adding a "drooping eave" on the outside of the cylinder opening. Lateral rain is guided by the skirt to drip off the outer wall and cannot be swept into the cylinder laterally. At the same time, the drooping eave reduces the top vortex, so that the airflow enters the sampling channel smoothly. This not only protects the absorbent sponge from being diluted by rainwater, but also maintains the stability of the airflow path and ensures the comparability of continuous sampling data on rainy days.

[0021] Furthermore, the telescopic rod is a multi-section sleeve telescopic structure, with elastic protrusions and recesses between adjacent sections to maintain a self-locking position after stepless length adjustment.

[0022] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the multi-section sleeve telescopic rod has built-in elastic protrusions and recesses, which realizes instantaneous self-locking after stepless extension and contraction. When adjusting, it can be stopped immediately by simply pulling or pressing, without the need for screws or pins, thus avoiding the loss of small parts in the field; the self-locking structure ensures that the rain cover and ventilation chamber remain stable with triangular support after being raised synchronously, preventing the cover from tipping over due to the upward shift of the center of gravity, and ensuring that the sampling device is still subjected to vertical force during the tall crop period.

[0023] Furthermore, the pointed conical guide head is threaded to the lower end of the second support rod, and the maximum outer diameter of the guide head is larger than the outer diameter of the second support rod to increase the anchoring area with the soil.

[0024] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the pointed conical guide head is threadedly connected to the second support rod, which allows for quick disassembly and replacement of worn drill bits; the maximum outer diameter of the guide head is larger than the outer diameter of the rod, forming an inverted conical anchoring cavity after being inserted into the soil, which significantly increases the lateral pull-out resistance. In the event of strong winds or heavy rain, the telescopic rod is not easily pulled out or tilted, ensuring that the coaxiality of the rain cover and the ventilation chamber remains unchanged, maintaining the constant geometry of the sampling space, and reducing data jumps caused by device displacement.

[0025] Furthermore, the lower outer wall of the external ventilation chamber is provided with an annular foot pedal, which extends radially outward to apply downward pressure to press the external ventilation chamber into the soil.

[0026] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the annular foot pedal on the lower outer wall of the external ventilation chamber provides the operator with a "foot pedal" force point. On-site, only one foot is needed to press the external ventilation chamber vertically into the wheat field soil without additional tools, avoiding contamination or damage caused by pressing the cylinder opening by hand; the foot pedal also serves as a limiting flange to prevent the cylinder from sinking excessively and causing insufficient sampling height, ensuring that the initial height is consistent each time it is deployed, and improving the repeatability of the plot test.

[0027] Furthermore, the absorbent sponge is a circular sheet with a diameter smaller than the inner ventilation chamber diameter, and the two absorbent sponges are respectively placed on top of the first positioning block and the second positioning block.

[0028] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the diameter of the circular absorbent sponge is slightly smaller than the inner ventilation chamber diameter, so it can be easily placed in but is still radially constrained by the positioning block to avoid shaking or falling off; the two sponges are placed on the top surface of the first and second positioning blocks respectively, forming a classic double-layer structure in which the upper layer isolates environmental ammonia and the lower layer captures soil ammonia. When replacing, it can be directly pulled out, simplifying the sampling process, reducing the risk of cross-contamination, and ensuring that the laboratory analysis results only reflect the true volatilization amount of that layer.

[0029] Furthermore, the external ventilation chamber, the internal ventilation chamber, and the rain cover are all integrally molded from transparent PVC material to balance the requirements of lightweight, corrosion resistance, and visual observation.

[0030] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the external ventilation chamber, the internal ventilation chamber, and the rain cover are all made of transparent PVC in one piece, which makes the whole weight light and saves effort in field transportation and high-altitude extension operations; the transparent material makes it easy to observe the sponge's moisture status, the liquid droplet residue inside the cylinder, and the position of the wheat plant tip, realizing visual maintenance, timely detection of blockages or overflows, and on-site treatment; PVC is resistant to ammonia and acid and alkali corrosion, and can be repeatedly washed and reused for many years, reducing the cost of experimental consumables and taking into account both environmental protection and economic benefits.

[0031] Compared with existing technologies, the beneficial effects of this utility model of an adjustable ammonia volatilization sampling device for wheat fields are as follows: This utility model integrates sampling channels, rain-proof systems, and anchoring structures into a slip-on device that can be raised in one step as the wheat plants grow taller, based on the core features of nested double cylinders, elastic locking, and synchronous telescoping. This allows for complete sequential observation of the same micro-area from the seedling stage to maturity without the need for re-distribution of sampling points. The inner and outer ventilation chambers slide coaxially, and the elastic latch locks instantly in any slot. Operators can adjust the height with one hand on the field ridge, avoiding stepping into the plot, compacting the soil, or breaking the plants. After adjustment, the nested section still maintains sufficient overlap, the bending stiffness of the cylinder is not reduced, and it is not prone to a chain failure of "top shaking - sponge friction - acid splashing" under strong winds. The positioning platform forms a ring-shaped step inside the cylinder, radially enclosing the sponge and suspending its bottom surface above the cylinder bottom. Even if rainwater flows in along the wall, it will first fall on the outside of the step and then seep down along the cylinder wall, keeping the sponge in a "dry zone" and maintaining its absorption capacity. The thickness of the step is less than the thickness of the sponge, ensuring that airflow can still pass evenly through the surrounding gaps, preventing "airflow detours—absorption blind zones" caused by local pressure differences. A transparent rainproof cover completely encloses the cylinder opening with its skirt, forming a linked triangular support with the telescopic rod. As the rod lengthens, the cover rises synchronously, with the cover edge always lower than the cylinder opening, forming an eave. Lateral rain is guided outward, and the top vortex is weakened, maintaining a vertically stable airflow path inside the cylinder, preventing rainwater dilution and reducing wind-induced fluctuations. The pointed conical guide head is threaded to the rod and can be replaced individually after wear. The maximum diameter of the conical surface is larger than the rod diameter, forming an inverted conical anchoring cavity after insertion into the soil, significantly increasing pull-out resistance. Even with soil expansion and contraction caused by alternating heavy rain and sun exposure, the device maintains its original azimuth angle, ensuring comparability of time series at the same location. The entire structure is made of transparent PVC, allowing for visual inspection of sponge moisture and residual droplets in the field, enabling early detection of abnormalities and on-site replacement; it is lightweight, allowing one person to carry and deploy it at multiple points, significantly reducing labor intensity. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the extended front view structure of this utility model;

[0034] Figure 2 This is a schematic diagram of the contracted main view structure of this utility model;

[0035] Figure 3 This is a schematic diagram of the rubber stopper extending as described in this utility model;

[0036] Figure 4 This is a schematic diagram of the rubber stopper clamping mechanism of this utility model;

[0037] The attached diagram lists the components represented by each number as follows:

[0038] 1. Rain cover; 10. Rubber stopper; 2. First support rod; 3. Second support rod; 4. Inner vent chamber; 5. Outer vent chamber; 6. Absorbent sponge; 7. First positioning block; 8. Second positioning block; 9. Slot. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0040] like Figure 1 , Figure 2 The diagram shown is an example of an adjustable aeration ammonia volatilization sampling device for wheat fields provided by this utility model, comprising:

[0041] The outer ventilation chamber 5 and the inner ventilation chamber 4 are coaxially fitted and can slide relative to each other axially. Both the outer ventilation chamber 5 and the inner ventilation chamber 4 are cylindrical bodies with both ends open.

[0042] An elastic latch is radially protruding from the outer wall of the inner ventilator 4, and a plurality of slots 9 are axially spaced on the wall of the outer ventilator 5. The elastic latch can engage with any slot to position the two ventilators at the required axial length.

[0043] Positioning platforms are fixed to the upper and lower parts of the inner wall of the inner ventilation chamber 4 respectively. The upper end of each positioning platform is used to horizontally support the absorbent sponge 6 impregnated with acid.

[0044] A transparent rainproof cover 1 is installed on the top of the outer ventilation chamber 5 and the inner ventilation chamber 4. The outer edge of the rainproof cover 1 extends downward to form a skirt, which surrounds the upper periphery of the two ventilation chambers.

[0045] At least two axially extendable telescopic rods, which from top to bottom include a first support rod 2 and a second support rod 3. The upper end of the first support rod 2 is detachably connected to the skirt, and the lower end of the second support rod 3 is provided with a pointed conical guide head. The guide head is used to insert into the soil to vertically fix the rain cover 1 and the two ventilation chambers.

[0046] In the above technical solution, the length of the fitting section between the external ventilation chamber 5 and the internal ventilation chamber 4 is not less than two-thirds of the total length of the internal ventilation chamber 4, so as to ensure coaxial stability throughout the telescopic process.

[0047] like Figure 3 , Figure 4As shown, further, in the above technical solution, the elastic latch is a rubber plug 10, the free end of which is hemispherical, and the diameter of the hemisphere is slightly larger than the opening width of the slot 9, so that elastic damping is generated after engagement.

[0048] Furthermore, in the above technical solution, the positioning platform includes a first positioning block 7 and a second positioning block 8 from top to bottom. The first positioning block 7 is fixed on both sides of the top of the inner ventilation chamber 4, and the second positioning block 8 is fixed on both sides of the bottom of the inner ventilation chamber 4. The positioning platform is equidistantly distributed along the circumference of the inner ventilation chamber 4. The radial width of the positioning platform is less than the thickness of the absorbent sponge 6, so that the absorbent sponge 6 is radially limited while its upper surface is exposed to the airflow.

[0049] Furthermore, in the above technical solution, the lower end face of the skirt of the rain cover 1 is lower than the upper end face of the two ventilation chambers, forming a shielding gap to prevent lateral rainwater from entering the ventilation chamber.

[0050] Furthermore, in the above technical solution, the telescopic rod is a multi-section sleeve telescopic structure, with elastic protrusions and recesses between adjacent sections to maintain a self-locking position after stepless length adjustment.

[0051] Furthermore, in the above technical solution, the pointed conical guide head is threadedly connected to the lower end of the second support rod, and the maximum outer diameter of the guide head is larger than the outer diameter of the second support rod, so as to increase the anchoring area with the soil.

[0052] Furthermore, in the above technical solution, the lower outer wall of the external ventilation chamber 5 is provided with an annular foot pedal, which extends radially outward to apply downward pressure to press the external ventilation chamber 5 into the soil.

[0053] Furthermore, in the above technical solution, the absorbent sponge 6 is a circular sheet with a diameter smaller than the inner diameter of the inner ventilation chamber 4, and the two absorbent sponges 6 are respectively placed on top of the first positioning block 7 and the second positioning block 8.

[0054] Furthermore, in the above technical solution, the external ventilation chamber 5, the internal ventilation chamber 4, and the rain cover 1 are all integrally molded from transparent PVC material to take into account the requirements of lightweight, corrosion resistance, and visual observation.

[0055] First Embodiment: This embodiment employs a double-latch and double-slot synchronous locking structure, suitable for the winter wheat-summer maize double-cropping area of ​​the Huang-Huai-Hai Plain. Both the outer and inner ventilation chambers are made of transparent PVC cylinders with a wall thickness of 2mm. Two cylindrical rubber plugs are symmetrically bonded to the outer wall of the inner ventilation chamber as elastic latches. Two sets of rectangular slots, three in each set, are punched at corresponding positions on the outer ventilation chamber, with an axial spacing of 40mm. During installation, the outer ventilation chamber is first vertically stepped into the center of the wheat ridge, leaving a predetermined height above the soil surface. Then, a circular sponge soaked in glycerol phosphate is placed in the inner ventilation chamber, supported by two annular positioning platforms, forming an absorption layer and an isolation layer. Next, the inner ventilation chamber is inserted into the outer ventilation chamber, gently pressed, and rotated 30°. The two rubber plugs simultaneously engage with their corresponding slots, achieving synchronous locking at two points and preventing tilting caused by unilateral force. The outer diameter of the rainproof cover's skirt is slightly larger than the outer diameter of the outer ventilator. Two three-section stainless steel telescopic rods are heat-fused to the center of the cover's top, with triangular guide heads at the rod ends that are directly inserted into the undisturbed soil between rows, forming a 120° triangular support. In this scenario, the daily increase in plant height after winter wheat turns green can reach 3cm. Researchers only need to lift the inner ventilator and telescopic rod simultaneously with one hand on the field ridge to complete the height adjustment within 30 seconds. No re-sampling is required throughout the entire jointing to heading stage, allowing for continuous acquisition of ammonia volatilization flux sequences. During rainy days, the rainproof cover's eaves will guide raindrops away from the nozzle, keeping the sponge intact and preventing it from falling off, meeting the region's requirement for "high-frequency sampling one week after topdressing."

[0056] Second embodiment: This embodiment adopts a lightweight structure with a single latch and stepped groove, suitable for small-scale experimental fields in the rice-wheat rotation area of ​​the middle and lower reaches of the Yangtze River. The outer ventilation chamber is still a transparent PVC cylinder, but the wall thickness is reduced to 1.5mm to reduce weight; the outer wall of the inner ventilation chamber is equipped with only a trapezoidal rubber stopper as an elastic latch, and a stepped continuous groove is punched in the outer ventilation chamber, with the groove width gradually narrowing from top to bottom, forming a damping effect that becomes tighter as you go up. The positioning platform is replaced with four independent fan-shaped protrusions, which are equidistantly bonded to the inner wall of the inner ventilation chamber. The thickness of the protrusions is 2mm less than the thickness of the sponge, so that the airflow can still pass evenly through the surrounding slits. There is only one eccentrically arranged carbon fiber telescopic rod under the skirt of the rain cover. The rod is hinged to the edge of the cover by a quick clamp and can be folded 90° around the hinge point for easy carrying; the guide head is a four-sided pyramid shape, which is conducive to insertion into rice stubble fields with high water content. In this scenario, wheat seedlings are often intercropped with overwintering rapeseed, resulting in narrow rows. The single-stem design reduces the space occupied by planting, allowing researchers to operate sideways. The stepped slots provide a "stepless fine-tuning" feel, enabling precise setting of the tube opening height for each point in plots with uneven plant heights, avoiding leaf pruning or seedling smothering. The entire device is about 30% lighter, allowing female researchers to carry ten sets with one hand. All adjustments are made within the positioning range of the elastic tongue and slots described in the claims, without introducing additional fasteners, fully meeting the sampling requirements of "lightweight, flexible, and low-disturbance" in rice-wheat rotation fields.

[0057] Specifically, the principle of this invention is as follows: the device follows a hierarchical principle of axial sliding sealing, radial elastic locking, and vertical linkage rain protection, changing the traditional fixed boundary to a variable boundary, allowing the sampling space to dynamically extend as the crop grows taller, while maintaining a constant airflow direction, absorption area, and rain protection coverage. The inner and outer ventilation chambers adopt a clearance fit, forming an annular thin slit between the cylinder walls, which allows axial sliding while blocking lateral airflow interference, ensuring that there is only a unidirectional flow from bottom to top in the cylinder before and after height adjustment; the elastic latch uses the elastic deformation of the material itself to store and release energy, and the hemispherical end generates an instantaneous "click" feedback when it crosses the edge of the slot. After locking, the root of the latch is under tension and the shoulder of the slot is under pressure, forming a self-tightening friction pair. The external load must first overcome this frictional force to trigger relative displacement, thus achieving stepless height adjustment and instantaneous self-locking without tools. The positioning platform is integrally bonded to the cylinder wall and is equidistantly distributed circumferentially, providing at least three points of constraint for the sponge, ensuring its center of gravity always falls on the cylinder axis. The top surface of the step is higher than the potential water accumulation surface, using surface tension differences to block water flow to the outside of the step. The bottom surface of the sponge maintains a constant distance from the soil evaporation surface through the inner edge of the step, and this distance does not change with height adjustment, thus ensuring a constant absorption path length. The rain cover and telescopic rod form a parallel mechanism; the cover rises synchronously when the rod extends, and the two maintain a constant relative position with the cylinder opening plane as a reference. The downward angle of the cover edge is greater than the maximum drift angle of rainwater, so raindrops from any direction are guided to the lower end of the skirt after contacting the cover wall and drip down along the outer wall, preventing them from entering the cylinder opening. The cover is transparent, allowing operators to visually confirm from a distance whether the cylinder opening is blocked by wheat plants or whether the sponge has shifted, reducing the frequency of opening the cover and minimizing human disturbance. The pointed guide head adopts a triangular cone surface. When inserted, the soil is radially pushed out by the cone surface. When pulled out, the cone surface forms an inverted wedge-shaped resistance. Its resistance torque is opposite to the wind load torque, thus keeping the cylinder vertical. The rod body is a multi-section sleeve. Adjacent sections form an interference fit through elastic protrusions and recesses. The meshing surface is a ball-and-socket match, which can withstand axial pressure and lateral shear, ensuring no swaying gap after frequent expansion and contraction.

Claims

1. A wheat field adjustable aeration ammonia volatilization sampling device, characterized in that, include: An outer ventilation chamber and an inner ventilation chamber are coaxially fitted and can slide relative to each other axially. Both the outer ventilation chamber and the inner ventilation chamber are cylindrical bodies with open ends. An elastic latch protrudes radially from the outer wall of the inner ventilator and a plurality of slots are spaced axially on the outer ventilator wall. The elastic latch can engage with any slot to position the two ventilators at the required axial length. Positioning platforms are respectively fixed to the upper and lower parts of the inner ventilation chamber wall, and the upper end surface of each positioning platform is used to horizontally support the absorbent sponge impregnated with acid. A transparent rain cover is installed on the top of the outer and inner ventilation chambers, and the outer edge of the rain cover extends downward to form a skirt, which surrounds the upper periphery of the two ventilation chambers. At least two axially extendable telescopic rods, the telescopic rods including a first support rod and a second support rod from top to bottom, the upper end of the first support rod being detachably connected to the skirt, and the lower end of the second support rod being provided with a pointed conical guide head, the guide head being used to insert into the soil to vertically fix the rain cover and the two ventilation chambers.

2. The adjustable aeration ammonia volatilization sampling device for wheat fields according to claim 1, characterized in that, The length of the fitting section between the outer vent and the inner vent is not less than two-thirds of the total length of the inner vent, to ensure coaxial stability throughout the telescopic process.

3. The adjustable aeration ammonia volatilization sampling device for wheat fields according to claim 2, characterized in that, The elastic latch is a rubber stopper with a hemispherical free end. The diameter of the hemisphere is slightly larger than the width of the slot opening, so that elastic damping is generated after engagement.

4. The adjustable aeration ammonia volatilization sampling device for wheat fields according to claim 3, characterized in that, The positioning platform includes a first positioning block and a second positioning block from top to bottom. The first positioning block is fixed on both sides of the top of the inner ventilation chamber, and the second positioning block is fixed on both sides of the bottom of the inner ventilation chamber. The positioning platforms are evenly distributed along the circumference of the inner ventilation chamber. The radial width of the positioning platform is less than the thickness of the absorbent sponge, so that the absorbent sponge is radially limited while its upper surface is exposed to the airflow.

5. The adjustable aeration ammonia volatilization sampling device for wheat fields according to claim 4, characterized in that, The lower end of the skirt of the rain cover is lower than the upper end of the two ventilation chambers, forming a shielding gap to prevent lateral rainwater from entering the ventilation chamber.

6. The adjustable aeration ammonia volatilization sampling device for wheat fields according to claim 5, characterized in that, The telescopic rod is a multi-section sleeve telescopic structure, with elastic protrusions and recesses between adjacent sections to maintain a self-locking position after stepless length adjustment.

7. The adjustable aeration ammonia volatilization sampling device for wheat fields according to claim 6, characterized in that, The pointed conical guide head is threaded to the lower end of the second support rod, and the maximum outer diameter of the guide head is larger than the outer diameter of the second support rod to increase the anchoring area with the soil.

8. The adjustable aeration ammonia volatilization sampling device for wheat fields according to claim 7, characterized in that, The lower outer wall of the external ventilation chamber is provided with an annular foot pedal, which extends radially outward to apply downward pressure to press the external ventilation chamber into the soil.

9. A wheat field adjustable aeration ammonia volatilization sampling device according to claim 8, characterized in that, The absorbent sponge is a circular sheet with a diameter smaller than the inner ventilation chamber diameter. The two absorbent sponges are placed on top of the first positioning block and the second positioning block, respectively.

10. A wheat field adjustable ammonia volatilization sampling device according to claim 9, characterized in that, The external ventilation chamber, internal ventilation chamber, and rain cover are all integrally molded from transparent PVC material to balance the requirements of lightweight, corrosion resistance, and visual observation.

Images