Modularized serial bidirectional plant planting device

Abstract

The invention discloses a modular serial bidirectional plant planting device. The two-way plant planting device comprises a plurality of two-way planting units connected in series, and each two-way planting unit comprises at least one two-way planting unit bottle body; openings are formed in the top and the bottom of the bottle body, and the diameter of the top opening is larger than that of the bottom opening; a fertilizing pipe with holes transversely penetrates through the middle upper part of the bottle body; a plurality of pressure compensation type drippers are arranged on the fertilizing pipe; the bottle body is sequentially provided with a planting layer substrate, a physical barrier layer, a water storage layer substrate and a supporting layer from top to bottom. According to the device, modular expansion, bidirectional planting (top leaf vegetables and bottom vines), quantitative and balanced fertilization and substrate hierarchical arrangement can be realized; the system is suitable for urban balconies, office walls, outdoor fences, kitchen gardens and other space scenes, and can also be used as a plant-substrate combined absorption platform for rural manure treatment, sewage ecological restoration and other occasions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of agriculture, horticulture, landscape ecological engineering and fertilization, and relates to a modularized and serially connected bidirectional plant planting device. BACKGROUND

[0002] The existing vertical greening system generally has problems of complex structure, uneven water distribution, crowded root system or low utilization efficiency, especially in narrow spaces such as family balconies and office walls, it is difficult to realize efficient utilization of three-dimensional space and automatic irrigation control.

[0003] In addition, the existing substrate material is mostly single structure, which cannot take into account the water retention, support and air permeability of plant growth, and the root support and overhanging growth of vine plants are not effectively optimized. SUMMARY

[0004] The purpose of the application is to provide a modularized and serially connected bidirectional plant planting device. The device can realize modularized expansion, bidirectional planting (top leafy plants and bottom vines), quantitative and balanced fertilization and hierarchical substrate setting. The system is suitable for space scenes such as urban balconies, office walls, outdoor fences and family gardens, and can also be used as a plant-substrate combined absorption platform for rural fecal pollution treatment and sewage ecological restoration.

[0005] The application provides a modularized and serially connected bidirectional plant planting device, which comprises a plurality of serially connected bidirectional planting units, each bidirectional planting unit comprising at least one bidirectional planting unit bottle body; the top and bottom of the bottle body are provided with openings, and the diameter of the top opening is greater than that of the bottom opening; a fertilizer pipe with holes is transversely arranged in the upper middle part of the bottle body, and a plurality of pressure-compensated drippers are arranged on the fertilizer pipe. The bottle body is sequentially provided with a planting layer substrate, a physical barrier layer, a water storage layer substrate and a support layer from top to bottom.

[0006] In the application, the pressure-compensated dripper is installed on the fertilizer pipe to ensure quantitative liquid discharge; the flow control of the pressure-compensated dripper is 1-2 L / h to ensure the uniformity of multi-unit fertilization.

[0007] In the above-mentioned modularized and serially connected bidirectional plant planting device, the planting layer substrate comprises the following components in volume or mass parts: coconut husk 40-70 parts, perlite 15-30 parts and vermiculite 20 parts; the planting layer substrate is used for plant growth and water storage and fertilizer retention.

[0008] In the above-mentioned modularized and serially connected bidirectional plant planting device, the water storage layer substrate comprises the following components in volume or mass parts: ceramic granules 40-60 parts, loofah 0-20 parts and rice husk charcoal 40-60 parts; the water storage layer enhances the water retention and slow-release performance.

[0009] The support layer comprises sponge and / or rock wool in the modular series connection bidirectional plant growing device. A reverse funnel-shaped barrier is arranged between the water storage layer substrate and the support layer to hold the substrate and keep water and fertilizer and allow the roots to grow through the bottle opening, thereby preventing the substrate of the water storage layer substrate 106 from leaking and increasing the water content of the layer. The support layer is mushroom-shaped with a large head and a small bottom, which can be clamped in the bottle opening to prevent it from falling off. The bottom of the bidirectional planting unit bottle is provided with a press-in slot (specifically three can be provided), and the press-in slot is arranged on the support layer to fix the support layer and prevent it from falling off. A slotted columnar sponge body is arranged in the press-in slot and can accommodate the roots of the vine plant after being clamped into the slot.

[0010] In the present application, the bottle body can be a plastic bottle body with the bottom cut off; the top of the bottle body is planted with leaf vegetables or landscape plants, and the bottom is planted with vine plants, which grow by hanging in the slot.

[0011] The thickness ratio of the planting layer substrate, the water storage layer substrate and the support layer in the modular series connection bidirectional plant growing device described above can be 1-3:3-10:1. Specifically, the thickness of the planting layer substrate can be 5cm-15cm; the thickness of the water storage layer substrate can be 15cm-50cm; and the thickness of the support layer can be 2cm-7cm.

[0012] The diameter of the physical barrier layer in the modular series connection bidirectional plant growing device described above is 1 / 3-4 / 5 of the diameter of the bottle body arranged thereon; the physical barrier layer prevents the substrate from sliding or water from rapidly infiltrating.

[0013] When each of the bidirectional planting unit comprises at least two bidirectional planting unit bottles, the bidirectional planting unit bottles are fixed in the modular fixing panel, which has a plurality of planting unit fixing openings with a diameter slightly larger than the diameter of the bidirectional planting unit bottle and smaller than the diameter of the fixing ring, for accommodating the bidirectional planting unit; the size and shape of the modular fixing panel can be designed according to requirements, and the position of the panel can be embedded in a certain structure according to actual conditions. The fertilizer pipes arranged through the bidirectional planting unit bottles are connected to the main fertilizer pipe through the fertilizer pipe joints to communicate with each other, i.e. the fertilizer pipe joints are used to connect the external fertilizer (irrigation) pipe and other planting units in series.

[0014] In the application, the main fertilization pipe is arranged, and different water sources or fertilizer sources are used according to the use purpose, such as water and fertilizer efficient resource utilization, the treated household liquid manure or sewage can be introduced into the system, since the fertilization pipe is buried in the middle of the substrate, the odor of manure or sewage can be isolated, and the breeding of mosquitoes and pests can be reduced. For example, the vertical greening and beautification of the balcony, office space and public area of the city family, the safe, odorless and colorless plant nutrient solution or clean water can be introduced to ensure the cleanliness and acceptance of the application in the family and office environment.

[0015] In the above-mentioned modularized and connected bidirectional plant growing device, a fixing ring is arranged on the outer wall of the bidirectional growing unit bottle body, and is used for fixing in the modularized fixing panel.

[0016] In the above-mentioned modularized and connected bidirectional plant growing device, a plurality of bidirectional growing unit bottles are connected with each other by vertical suspension.

[0017] In the above-mentioned modularized and connected bidirectional plant growing device, the two ends of the fertilization pipe arranged in the bidirectional growing unit bottle body are respectively provided with a hanging rope, and all the hanging ropes are fixed on a hanging frame, and the hanging frame is used for fixing the modularized and connected bidirectional plant growing device.

[0018] In the application, each bottle body can be transversely and longitudinally spliced through a quick plug connection pipe to realize modularized matrix arrangement. Figure 4 As shown in the drawing, the quick plug connection pipe is clamped in a circular port with a diameter less than or equal to the diameter of the bottle body from top to bottom, and a fixing ring is arranged on the outer wall of the bidirectional growing unit bottle body and is used for fixing in the modularized fixing panel.

[0019] The application has the following beneficial effects: 1. The same device realizes bidirectional plant growing of “upper leafy vegetables and lower climbing vines”, and greatly improves the unit space utilization rate; 2. The substrate design is scientific and meets the planting, water storage and supporting functions; 3. The pressure compensation dripper ensures the uniformity of fertilization, and is suitable for family or city green wall; 4. The physical barrier cooperates with the funnel type baffle cover to realize efficient use of water and fertilizer by plants and to prevent leakage.

[0020] 5. The modular splicing mode is flexible, and is convenient for expansion and installation; 6. The application can be combined with a renewable liquid fertilizer resource system to realize a green and low-carbon agricultural scheme; 7. It meets the balcony vegetable growing needs of ordinary farmers, and is suitable for the construction of vertical landscape in family, office and public space. 8. As a construction unit of substrate infiltration or constructed wetland system, it can efficiently absorb nitrogen and phosphorus resources in manure or reclaimed water, realize landscape greening and pollutant resourceization double functions. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a profile structure diagram of the device; Figure 2 is a top view of the device; Figure 3 is a bottom view of the device; Figure 4 is a connection diagram of the modular device based on panel fixation; Figure 5 is a series connection diagram of the modular device based on suspension.

[0022] Figure 6 is a fertilizer amount setting.

[0023] Figure 7 is the average air temperature of the test field.

[0024] Figure 8 is the sampling position of the device.

[0025] Figure 9 is the annual dynamic change of pH in each layer of the substrate with different fertilizer amounts.

[0026] Figure 10 is the annual dynamic change of soil electrical conductivity / soil salt accumulation (EC 1:5 ) in each layer of the substrate with different fertilizer amounts Figure 11 is the annual dynamic change of TOC content in each layer of the substrate with different fertilizer amounts.

[0027] Figure 12 is the annual dynamic change of Kjeldahl nitrogen content in each layer of the substrate with different fertilizer amounts.

[0028] Figure 13 is the annual dynamic change of nitrite nitrogen content in each layer of the substrate with different fertilizer amounts.

[0029] Figure 14 is the annual dynamic change of nitrate nitrogen content in each layer of the substrate with different fertilizer amounts.

[0030] Figure 15 is the annual dynamic change of ammonia nitrogen content in each layer of the substrate with different fertilizer amounts.

[0031] Figure 16 is the change of urease activity in different fertilizer amount treatments.

[0032] Figure 17 is the change of sucrose activity in different fertilizer amount treatments.

[0033] Figure 18 Changes of cellulase activity for different fertilization treatments.

[0034] Figure 19 Changes of protein content in vegetable leaves for different fertilization treatments.

[0035] Figure 20 Changes of glucan content in vegetable leaves for different fertilization treatments.

[0036] Figure 21 Changes of nitrate content in vegetable leaves for different fertilization treatments.

[0037] Figure 22 Ammonia and nitrogen oxide emissions for different fertilization treatments and fertilization methods.

[0038] Figure 23 Substance flow of regenerated liquid fertilizer in the atmosphere-plant-substrate for different fertilization treatments.

[0039] The various marks in the drawings are as follows: 100 bidirectional planting unit bottle; 101 planting layer substrate; 102 hanging ring or hanging port for overall fixing and hanging of the bottle; 103 fertilization (irrigation) pipe with holes; 104 fixing ring; 105 physical barrier layer; 106 water storage layer substrate; 107 support layer (rock wool); 108 plug-in slot (three); 109 slotted columnar sponge body; 110 shield cover; 111 fertilization pipe joint; 112 pressure-compensating dripper; 113 top-planted leaf vegetables or landscape plants; 114 bottom-planted vine plants; 115 modularized fixing panel; 116 fertilization (irrigation) pipe; 117 four-way joint; 118 planting unit fixing port; 119 hanging rope; 120 hanging rack. DETAILED DESCRIPTION

[0040] The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0041] The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0042] The present application provides a modularized bidirectional plant planting device (as shown in Figures 1-3 The present application provides a modularized bidirectional plant planting device (as shown in The bottle body is sequentially provided from top to bottom with a planting layer substrate 101, a physical barrier layer 105, a water storage layer substrate 106, and a support layer 107; The planting layer substrate 101 has a thickness of 5 cm to 15 cm, specifically 7 cm, and is mixed and filled with 40% to 70% coconut husk (specifically 60%) + 15% to 30% perlite (specifically 20%) + 15% to 30% vermiculite (specifically 20%) in terms of volume or mass ratio, taking into account plant growth and water storage and fertilizer retention; The water storage layer substrate 106 has a thickness of 15 cm to 50 cm (the maximum thickness is determined according to the height of the planting unit bottle), and is selected to be 35 cm. The mass ratio of the components of the water storage layer substrate is as follows: 40% to 60% ceramic (specifically 45%) + 0% to 20% loofah (specifically 10%) + 40% to 60% rice husk charcoal (specifically 45%) to enhance water retention and slow-release performance; The lower support layer 107 is filled with 2 cm to 7 cm thick (specifically 5 cm) rock wool or high-density sponge, which holds the substrate and allows the roots to grow through the bottle opening.

[0043] Further, a hard PVC fertilization pipe 103 is installed in the middle of each bottle body, with a depth of 5 cm to 20 cm (specifically 7 cm), and pressure-compensating drippers 112 are arranged equidistantly (3 cm to 10 cm, specifically 5 cm) to ensure uniformity of multi-unit fertilization; Further, a circular physical barrier layer 105 is horizontally arranged at the junction of the upper substrate and the middle substrate, with a diameter of 1 / 3 to 4 / 5 of the diameter of the bottle body, specifically 2 / 3.

[0044] Further, there are currently two ways to hang or fix the device, namely modular connection based on a fixed panel, and the device has strong expandability. Specifically, one is as shown in Figure 4 When each bidirectional planting unit includes at least two bidirectional planting unit bottles, the bidirectional planting unit bottles are fixed by a modular fixed panel, which has a plurality of planting unit fixing openings with a diameter slightly larger than the diameter of the bidirectional planting unit bottle and smaller than the diameter of the fixing ring, for arranging the bidirectional planting unit. The modular fixed panel must be made of hard material and is not easy to deform. Its size and shape can be designed according to needs, and the position of the panel can be embedded in a certain structure according to actual conditions. The fertilization pipes arranged through the bidirectional planting unit bottles are connected to the main fertilization pipe through a fertilization pipe joint to communicate with each other, i.e., the fertilization pipe joint is used to connect the external fertilization (irrigation) pipeline and series connect other planting units; The other is as shown in Figure 5As shown, based on the suspended modular series, multiple two-way planting units are connected with each other by vertical suspension; two ends of the fertilizer pipe penetratingly arranged in the bottle body of each two-way planting unit are respectively provided with a suspension rope, and all the suspension ropes are fixed on a suspension frame for fixing the modular series two-way plant planting device.

[0045] Embodiment The present study takes the device as a carrier to carry out planting test for the purpose of absorbing and utilizing the generated fecal pollution in rural courtyards, and explores the comprehensive effect on crop growth, substrate nutrient accumulation and environmental impact.

[0046] The fermentation raw material used in the test is taken from the third grid of a three-grid anaerobic digester in a test base in Jiangsu. The three-grid anaerobic digester collects sanitary sewage wastewater from a micro-water toilet flushing system and a kitchen waste crusher, wherein the toilet flushing water volume is ≤1.5 L / time, and the sum of the hydraulic retention time of the first two grids of the three-grid anaerobic digester is not less than 30 days. The properties of the regenerated liquid fertilizer are as shown in Table 1.

[0047] Table 1 Properties of regenerated liquid fertilizer

[0048] According to the water and fertilizer requirements and growth requirements of crops, local plants with short growth period, large water requirement and easy growth are selected, and edible and commercially valuable varieties are preferred. Since the nitrogen demand of vegetable crops is large, small Chinese cabbage is selected as the top planting leaf vegetable or landscape plant 113, and cucumber is selected as the bottom planting vine plant 114. The vegetables are uniformly sown by dibbling method, the cucumber seedling root system is placed in the slotted columnar sponge body 109, and the whole is inserted into the 108 insertion slot. The particle size of all the substrates is 1-3 cm.

[0049] Based on the guide fertilization amount of 280 kg·N / ha / a nitrogen, the total amount of nitrogen after conversion should not exceed 28 g / m 2 . The total nitrogen concentration of the regenerated liquid fertilizer is about 1.07 g / L, and the corresponding fertilization volume is 80 mL. In order to improve water and fertilizer utilization efficiency and reduce environmental risk, fertilization + compensatory irrigation is set to run alternately every day for 14 months, which is divided into four stages, and 0-12 times of fertilization amount is set before and after. For example Figure 6 , stage I is from January to April, and the fertilization amount is set to 0, 150, 300, 375, 450 mL. Stage II is from April to July, during which planting, fertilization and monitoring are stopped. Stage III is from July to October, during which the fertilization amount is increased to 0, 300, 600, 900, 1500 mL. Stage IV is from October to February of the next year, and the fertilization amount is increased again to 0, 1500, 2100, 2700, 3600 mL.

[0050] For example Figure 7The average temperature of the test field showed that planting stages I, III, and IV basically covered the average temperature distribution of the test field. Therefore, only the previous stage (stage III) was selected for planting experiments in stages II and III. Average temperature: stage III > stage I > stage IV.

[0051] The first batch of sowing experiments was conducted in December 2022, and matrix and vegetable samples were collected in January, February, March, April, July, August, October, December 2023, and February 2024. After removing plant residues, the matrix was mixed and divided into two parts. One part of the matrix sample was air-dried and passed through a 1 mm sieve, and the other part was stored at -20 ℃ for determination of matrix chemical properties and matrix enzyme activity; plant fresh samples were collected (sampling locations as shown in Figure 8 The sugar content, protein content, nitrate nitrogen, and nitrite nitrogen of the leaves were determined.

[0052] 1. Effect of fertilizer application rate on matrix physicochemical properties As shown in Figure 9 , the fertilizer application rate had a significant effect on the change in matrix pH, especially in the surface layer. With the increase in fertilizer application rate, the pH of the matrix showed a downward trend as a whole, which was particularly evident in stages III and IV. Under high fertilizer application rate (3600 kg·N / ha / a), the pH of the surface layer of the matrix gradually decreased from 8.2 at the beginning to 7.35 at the 14th month, showing a significant acidification effect. Under relatively low fertilizer application rate (150-600 kg·N / ha / a), the pH decreased relatively slowly, indicating that the acidification effect caused by less nitrogen input was weaker.

[0053] During the experiment, the pH of the substrate showed dynamic fluctuations with time and temperature. In stage I and stage III, the pH of the surface and upper layers of the substrate decreased significantly with increasing fertilizer application rates. In particular, in stage III, the pH of the surface layer decreased to about 7.48, which may be related to the promotion of nitrification and the increase of hydrogen ion release at high temperatures. In stage IV, the pH change was significantly reduced due to the decrease in temperature, indicating that nitrification was inhibited under low temperature conditions, and the acidification effect was also weakened. The pH of different layers of the substrate showed a significant gradient difference. The pH of the surface layer fluctuated the most, decreasing from 8.2 to 7.35 under high fertilizer application rates, while the pH of the upper and bottom layers changed more gently. The pH of the bottom layer remained between 7.8 and 8.0 during stages I and III. This may be related to the weak migration ability of ammonia nitrogen, which is easily adsorbed by the substrate colloid, resulting in a lack of nitrogen source and dissolved oxygen for nitrification in the lower layer of the substrate, and the weak nitrification reaction leading to no significant decrease in pH. The EC of the substrate reflects the concentration of soluble salts in the substrate, and is usually positively correlated with fertilizer application rates. When the fertilizer application rate increases, the accumulation of soluble salts such as nitrate and ammonium salts in the substrate leads to an increase in the EC value of the substrate. Currently, the EC value is commonly used internationally to assess the degree of substrate salinization. In Europe and the United States, an EC value of 4.00 mS / cm is used as the threshold for the onset of substrate salt damage, an EC value of 8.00 mS / cm is used as the standard for moderate salt damage to crops, and an EC value of 16.00 mS / cm indicates that the growth of crops has stopped (died). Therefore, substrate salt damage can be divided into three levels: mild (4-8 mS / cm), moderate (8-16 mS / cm), and severe (>16 mS / cm). In China, substrate salinization is divided into four levels based on crop growth and development, and the total salt content of the substrate is used as the classification index. In this experiment, the EC value of the surface layer of the substrate increased significantly with increasing fertilizer application rates, especially under high fertilizer application rates (1500-3600 kg·N / ha / a), the surface EC value approached 4.00 mS / cm, indicating an increased risk of salt accumulation in the substrate. If the fertilizer application rate continues to increase or the time is extended, the substrate may enter the salt damage stage. In addition, the effect of fertilizer application rate on the pH of the substrate also indirectly affects the EC value. In stages III and IV, the pH of the surface layer of the substrate decreased to 7.4-7.6, and the acid environment helped to accumulate soluble salts, further increasing the EC value, indicating that the acidification effect was more significant under conditions of high salt accumulation. During the 14-month experiment, the change in the EC value of the substrate was greatly affected by time and temperature. In stage I with low fertilizer application rates (150-450 kg·N / ha / a), the EC value of the substrate was relatively stable, and the EC value of the surface layer of the substrate remained between 0.50 and 1.50 mS / cm, and did not reach the salt damage threshold.However, in stage III and stage IV with high fertilization rate, the EC value of the surface layer of the substrate increased significantly, especially in the treatment of 3600 kg·N / ha / a, the EC value reached 3.855 mS / cm. However, although the fertilization rate in stage IV was doubled, the increase in EC value was small. This may be related to the evaporation under low temperature conditions in winter, which slows down the evaporation of water and the concentration of salt in the substrate, resulting in a decrease in the increase of EC value after increasing the fertilization rate. Figure 10 The EC value of the substrate at different fertilization rates reflects the annual dynamic change of the EC value of the substrate at different depths. The EC value decreases significantly with the increase of the depth of the substrate. The surface layer of the substrate (0~5 cm) is most affected by the fertilization rate and evaporation, and the EC value is close to 4.00 mS / cm. The EC value of the planting layer (5~25 cm) and the bottom layer (50~75 cm) is maintained below 1.00 mS / cm, indicating that the salt accumulation in the deep layer of the substrate is less, and far from reaching the salt damage standard. The physical barrier set in the surface layer effectively prevents the migration of soluble salts to the deep layer, which makes the salt concentrate in the surface layer.

[0054] Total organic carbon (TOC) is an important component of soil organic matter, which reflects the accumulation and decomposition process of soil organic matter. The application of regenerated liquid fertilizer provides a large amount of organic matter input to the substrate, which has a significant impact on the accumulation of TOC. Experimental data show (as shown in Figure 11 With the increase of fertilization rate, the TOC value in the surface and upper layer of the substrate showed a significant upward trend, especially under high fertilization rate, the accumulation effect of TOC was particularly significant.

[0055] In the surface layer, TOC values fluctuated greatly throughout the experiment. In phase I with low fertilizer rates (150-450 kg·N / ha / a), the TOC in the surface layer increased slightly, with a maximum value of 6.984%. However, with increasing fertilizer rates, especially in phases III and IV (1500-3600 kg·N / ha / a), the TOC in the surface layer increased rapidly, reaching a maximum value of 7.947%. The TOC trend in the upper layer was similar to that in the surface layer, but the cumulative amplitude was relatively small. In phase IV with high fertilizer rates, the TOC in the upper layer reached a peak value of 11.788%. This also indicates that the active heterotrophic microorganisms in the surface layer consumed TOC, while the organic matter intake rate under high fertilizer rates was greater than the consumption rate, leading to the accumulation of TOC in the surface layer. In terms of TOC accumulation, high fertilizer rates of renewable liquid fertilizer are beneficial to substrate nutrient storage and improvement. In contrast, the TOC in the bottom layer remained relatively stable, even under high fertilizer rates, with a maximum value of 5.653%. In addition, the pH of the substrate also had an impact on the change in TOC. Lower pH values generally contribute to the decomposition and transformation of organic matter, thereby increasing the organic carbon content in the substrate. Under high fertilizer rates, the pH of the surface and upper layers decreased to 7.4-7.6, and this acidification effect promoted the decomposition of organic matter and accelerated the release and accumulation of organic carbon. Especially in phases III and IV, the decrease in pH value was synchronized with the increase in TOC value, indicating that the decomposition efficiency of organic matter was significantly improved in an acidic environment. At the same time, low pH values also stimulate microbial activity, further enhancing the ability of microorganisms to decompose organic matter, thereby increasing the organic carbon content in the substrate.

[0056] Fertilizer rates were significantly positively correlated with TKN content in the substrate, especially under high fertilizer rates (1500-3600 kg·N / ha / a), with a significant cumulative effect of TKN in the surface layer. The data showed that the TKN content in the surface layer increased from 0.018% to 0.075% under high fertilizer rates, which was 4.17 times higher than that under low fertilizer rates. This indicates that the decomposition of organic matter in the surface layer was significantly enhanced under high fertilizer rates, resulting in the accumulation of TKN in the surface layer. Figure 12), under high fertilizer application rate, the TKN value of surface layer reached 25% peak, and the organic nitrogen and ammonium nitrogen in the regenerated liquid fertilizer provided a stable nitrogen source for the substrate, greatly improving the accumulation of TKN. In the high fertilizer application rate stage of the experiment, the pH value of the surface layer substrate decreased, and this acidification effect reduced the volatilization loss of ammonia nitrogen, thereby enhancing the accumulation of nitrogen. Related studies have shown that long-term application of organic nitrogen fertilizer not only increases the nitrogen content of the substrate, but also further optimizes the transformation and dynamic balance of nitrogen by promoting the activity and abundance of nitrogen cycling microorganisms. Especially under high fertilizer application rate, the toxic effect of high ammonia nitrogen is enhanced, which makes it difficult for nitrogen to transform and is not conducive to the nutrient absorption of plant roots, thereby increasing the accumulation effect of TKN. The change trend of TKN in different fertilizer application stages also reflects the influence of fertilizer application rate and time on nitrogen accumulation. In stage I (150~450 kg·N / ha / a) and stage III (300~1500 kg·N / ha / a), the TKN value of the surface layer substrate maintained between 1.8%~8.4%, and the TKN content of the planting layer and the bottom layer changed little, the accumulation effect of nitrogen was relatively slow, and the supply and demand of nitrogen were basically balanced, while the nitrogen application rate of 1500 kg·N / ha / a did not accumulate in stage III, which may be due to the higher temperature in this stage, which promotes the transformation of nitrogen, while stage IV is the opposite, and TKN accumulates. However, with the increase of fertilizer application rate, especially under high fertilizer application rate in stage III and stage IV, the TKN content of the surface and upper layer substrate increased significantly, and the TKN value of the surface layer reached 25.0% in stage IV. This enhancement of nitrogen accumulation is closely related to time and temperature, and moderate fertilization can not only increase the nitrogen content of the substrate, but also optimize the functional activity of nitrogen cycling microorganisms. The vertical distribution of TKN shows that the TKN content decreases significantly with the increase of substrate depth. The TKN accumulation in the surface layer is the most significant, and the TKN value of the 0~5 cm deep layer substrate under high fertilizer application rate is much higher than that of the planting layer and the bottom layer, indicating that the physical barrier effectively prevents the penetration of nitrogen to the deep layer, and the kjeldahl nitrogen is mainly in the form of ammonia nitrogen, which is easy to be fixed by the substrate, so that nitrogen is mainly accumulated in the surface layer substrate. According to the TKN accumulation of the surface layer substrate, 0~900 kg·N / ha / a is in a dynamic balance of intake-consumption in stage I and stage III, while more than 900 kg·N / ha / a, the surface and upper layer substrate accumulates, but the lower layer (50~75 cm) does not accumulate significantly, which means that it does not pose a potential pollution risk to the environment.

[0057] Ammonia nitrogen is the main form of nitrogen in regenerated liquid fertilizer, which directly affects the accumulation of nitrogen in the substrate after fertilization. With the increase of fertilizer application rate, the ammonia nitrogen content in the substrate increases significantly, especially in the surface layer. The accumulation trend of ammonia nitrogen and kjeldahl nitrogen is similar. Experimental data show ( Figure 15), the ammonia nitrogen content in the surface layer of the substrate reached 19.726 mg / L, while under higher fertilizer application (3600 kg·N / ha / a), the ammonia nitrogen content further increased to 26 mg / L. This high ammonia nitrogen concentration not only promotes the accumulation of nitrogen in the substrate, but also increases the risk of ammonia gas volatilization, which in turn adversely affects air quality. In addition, ammonia nitrogen is mainly concentrated in the surface layer of the substrate, while in the deep layer of the substrate, the ammonia nitrogen content is relatively low (about 3.038 mg / L). Ammonia nitrogen is easily adsorbed by clay minerals and organic matter in the substrate, reducing the mobility of ammonia nitrogen. Also in stage III, 1500 kg·N / ha / a ammonia nitrogen does not accumulate, and when the amount exceeds 2700 kg·N / ha / a, ammonia nitrogen begins to accumulate in the deep layer of the substrate.

[0058] Nitrite nitrogen is an intermediate product of nitrification, usually with low content. However, under conditions of high ammonia nitrogen concentration and low temperature, the activity of nitrifying bacteria is inhibited, leading to the accumulation of nitrite nitrogen in the substrate. In stage III (1500 kg·N / ha / a), the content of nitrite nitrogen in the surface layer of the substrate reached 246.117 mg / L, while in stage IV (3600 kg·N / ha / a) with higher fertilizer application, the content of nitrite nitrogen increased to 532 mg / L ( Figure 13 ). Excessive accumulation of nitrite nitrogen can lead to plant nitrite poisoning, especially when the crop root system absorbs too much nitrite nitrogen. When the content of nitrite nitrogen in the substrate is high, plants will experience nutrient imbalance, affecting normal growth. Another potential risk of nitrite nitrogen accumulation is its interaction with nitrate, increasing the possibility of groundwater pollution.

[0059] Figure 14 It is shown that in stage III (1500 kg·N / ha / a), the content of nitrate nitrogen in the surface layer of the substrate reached 888.7 mg / L, indicating that under conditions of high fertilizer application, although nitrification is enhanced to a certain extent, due to the high content of ammonia nitrogen, part of the nitrifying bacteria may be inhibited, leading to the nitrification process not reaching the maximum potential. In stage IV (3600 kg·N / ha / a), the content of nitrate nitrogen also reached 621.0 mg / L, although the fertilizer application increased, the nitrification was inhibited by excessive ammonia nitrogen, and the conversion rate decreased. Nitrate nitrogen accumulation not only occurs in the surface layer of the substrate, but also in the deep layer of the substrate, the content of nitrate nitrogen increases to a certain extent. Nitrate nitrogen has high mobility and is easily transported with water to the deep layer of the substrate, the content of nitrate nitrogen in the bottom layer of the substrate under conditions of high fertilizer application reached 399.2 mg / L, which indicates that nitrate nitrogen has strong mobility and is easily transported with water to the deep layer, increasing the risk of groundwater pollution.

[0060] During high-fertilization phases III and IV, the pH of the surface substrate gradually decreased, reaching as low as approximately 7.45. This acidification effect promoted the conversion of ammonia nitrogen, accelerated nitrification, and led to an increase in nitrate nitrogen production. However, excessive ammonia nitrogen could also inhibit the activity of nitrifying bacteria and increase the accumulation of nitrite nitrogen. Especially under low-temperature conditions, the conversion rate of ammonia nitrogen to nitrate nitrogen slowed significantly, resulting in an imbalance in the conversion of nitrogen between different forms. The distribution of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen was also closely related to the substrate's electrical conductivity and organic carbon. Under high-fertilization conditions, soluble salts in the substrate increased significantly, resulting in an EC value approaching 4.00 mS / cm, indicating an increased risk of salt accumulation. Simultaneously, the TOC value increased significantly under high fertilization, reaching a maximum of 7.947%. These indicators reflect the comprehensive impact of fertilization management on the physicochemical properties of the substrate.

[0061] 2. Effects of fertilizer application rate on substrate enzyme activity Urease is a key enzyme in the substrate nitrogen cycle, catalyzing the hydrolysis of urea to produce ammonia nitrogen and carbon dioxide, thereby promoting nitrogen availability and improving the efficiency of nitrogen uptake by plants. Therefore, urease activity is crucial for nitrogen conversion, ammonia nitrogen release, and the availability of substrate nitrogen.

[0062] Under conditions of low fertilizer application (150~450 kg·N / ha / a) Figure 16 Urease activity was high in the substrate, especially in the top layer, where it reached a maximum of 13.92 μg / d / g. This indicates that appropriate fertilization helps maintain and promote urease activity, thereby improving nitrogen conversion efficiency. However, as the fertilization rate increased to 1500 kg·N / ha / a and higher, urease activity in the top layer began to decrease significantly. For example, under a fertilization condition of 3600 kg·N / ha / a, urease activity dropped to 9.63 μg / d / g. This phenomenon may be due to the excessive accumulation of ammonia nitrogen inhibiting the activity of microorganisms in the substrate. In particular, excessively high ammonia nitrogen concentrations may have altered the composition of the microbial community, leading to the inhibition of urease activity. Urease activity decreased with increasing substrate depth, with the highest urease activity in the top layer and relatively low activity in the planting layer and bottom layer. For example, at a fertilization rate of 1500 kg·N / ha / a, the urease activity in the bottom layer was only 0.05 μg / d / g. This may be due to the limited accumulation of ammonia nitrogen in the underlying substrate and the physical barriers restricting the vertical migration of nitrogen. High fertilization rates (>900 kg·N / ha / a) have a significant negative impact on substrate urease activity and nitrogen cycling. Excessive accumulation of ammonia nitrogen not only inhibits the activity of substrate microorganisms, leading to reduced urease activity, but may also trigger substrate acidification, further affecting the volatilization rate of ammonia nitrogen.

[0063] Sucrase is a key enzyme in the carbon cycle of the substrate, which can decompose sucrose into glucose and fructose. Its activity directly reflects the dynamic changes of carbon cycle in the substrate. Sucrase activity is affected by many factors such as organic matter content, structure and fertility of the substrate. Therefore, the study of sucrase activity can help reveal the changes of substrate fertility and the effects of regenerated liquid fertilizer on the health of the substrate.

[0064] As Figure 17 The data showed that the relationship between sucrase activity and fertilizer application rate was complex. In the low fertilizer application stage (150-450 kg·N / ha / a), the sucrase activity in the surface layer of the substrate increased with the increase of fertilizer application rate. When the fertilizer application rate reached 450 kg·N / ha / a, the sucrase activity in the surface layer of the substrate reached the maximum value of 168.9 μg / d / g. Similarly, other soil layers also showed similar trends, especially in the 50-75 cm deep substrate, the sucrase activity increased under high fertilizer application rate, which reflected the penetration effect of fertilizer on the carbon cycle of deep substrate. However, with the increase of fertilizer application rate to 1500-3600 kg·N / ha / a, the sucrase activity decreased as a whole. High nitrogen conditions may lead to imbalance of microbial community, affecting the secretion and activity of sucrase. In addition, the change of substrate pH may also be related to the decrease of sucrase activity. Studies have shown that the use of excessive nitrogen fertilizer may inhibit the activity of microbial community in the substrate, thereby affecting the efficiency of carbon cycle. The inhibition of low temperature environment in winter on microorganisms may also be one of the reasons for the decrease of sucrase activity. From the depth of the substrate, the sucrase activity gradually decreased with the increase of the depth of the substrate, and the sucrase activity in the surface layer of the substrate was the highest, which indicated that the application of regenerated liquid fertilizer mainly affected the carbon cycle in the surface layer of the substrate. In the bottom layer of the substrate at the depth of 50-75 cm, the sucrase activity was generally low. In addition, the low pH value of the bottom layer of the substrate may also inhibit the activity of microorganisms, further limiting the secretion of sucrase.

[0065] Cellulase is a key enzyme in the substrate that decomposes cellulose in plant cell walls, and its activity can directly reflect the decomposition ability of microorganisms in the substrate. In the low fertilizer application stage (such as 150-450 kg·N / ha / a), the cellulase activity in the surface layer of the substrate increased with the increase of fertilizer application rate. When the fertilizer application rate reached 450 kg·N / ha / a, the cellulase activity in the surface layer of the substrate reached the maximum value of 0.9 μg / d / g. Similarly, other soil layers also showed similar trends, especially in the 50-75 cm deep substrate, the cellulase activity increased under high fertilizer application rate, which reflected the penetration effect of fertilizer on the carbon cycle of deep substrate. However, with the increase of fertilizer application rate to 1500-3600 kg·N / ha / a, the cellulase activity decreased as a whole. High nitrogen conditions may lead to imbalance of microbial community, affecting the secretion and activity of sucrase. In addition, the change of substrate pH may also be related to the decrease of sucrase activity. Studies have shown that the use of excessive nitrogen fertilizer may inhibit the activity of microbial community in the substrate, thereby affecting the efficiency of carbon cycle. The inhibition of low temperature environment in winter on microorganisms may also be one of the reasons for the decrease of sucrase activity. From the depth of the substrate, the sucrase activity gradually decreased with the increase of the depth of the substrate, and the sucrase activity in the surface layer of the substrate was the highest, which indicated that the application of regenerated liquid fertilizer mainly affected the carbon cycle in the surface layer of the substrate. In the bottom layer of the substrate at the depth of 50-75 cm, the sucrase activity was generally low. In addition, the low pH value of the bottom layer of the substrate may also inhibit the activity of microorganisms, further limiting the secretion of sucrase. Figure 18The cellulase activity showed a relatively stable upward trend in stage I, especially under the treatment of 450 kg N / ha / a, the cellulase activity of the surface layer reached 17.77 μg / d / g, while the activities of the upper and bottom layers were 16.66 μg / d / g and 19.20 μg / d / g, respectively. With the increase of fertilizer amount, the cellulase activity further increased, especially under the treatment of 1500 kg N / ha / a, the cellulase activity of the surface layer and the upper layer reached the maximum value, which were 25.44 μg / d / g and 19.41 μg / d / g, respectively. When the fertilizer amount exceeded 1500 kg N / ha / a (such as 3600 kg N / ha / a in stage IV), the cellulase activity began to decrease, especially under the treatments of 2700 kg N / ha / a and 3600 kg N / ha / a, the cellulase activity of the surface layer and the upper layer decreased significantly. This indicated that excessive fertilization might inhibit the decomposition activity of microorganisms, leading to the decrease of the decomposition efficiency of organic matter in the substrate.

[0066] 3. Effect of fertilizer amount on the physicochemical properties of vegetables Figure 19 It was shown that the increase of fertilizer amount significantly affected the protein content of leaves in the same stage. In stage I (2-4 months), with the increase of fertilizer amount, the protein content of leaves increased steadily from 562 mg / kg without fertilization to 633 mg / kg under the maximum fertilizer amount of 450 kg N / ha. However, in stages III and IV, especially under the condition of high fertilizer amount, the protein content of leaves decreased instead. This might be due to the excessive fertilizer amount, which exceeded the nitrogen demand of plants, leading to the ineffective absorption of excessive nitrogen, and the high ammonia environment inhibited the absorption efficiency of plant roots, thereby inhibiting the accumulation of protein. The change of protein content in leaves was also affected by temperature. In the high temperature period of stage III, the protein content increased, which might be due to the change of physiological metabolism of plants under high temperature environment, leading to the increase of protein synthesis rate. While in the low temperature period, the protein content decreased.

[0067] Figure 20The results showed that, within the same stage, increased fertilization significantly affected leaf polysaccharide content. In stage I, the leaf polysaccharide content in the 375 kg·N / ha fertilization treatment remained at 6.30%, significantly higher than that in the low 150 kg·N / ha fertilization treatment. Unlike the changes in protein content, leaf polysaccharide content remained high under high fertilization conditions, but in stage IV, with excessively high fertilization (3600 kg·N / ha), leaf polysaccharide content also decreased significantly. The trend of polysaccharide content over time was similar to that of protein content. During the high-temperature periods of stages III and IV, polysaccharide content decreased, which may be related to the reduced photosynthetic efficiency of plants under high-temperature conditions. Simultaneously, polysaccharides are products of environmental stress, and salt damage caused by excessive fertilization may have further inhibited polysaccharide accumulation.

[0068] Figure 21 This indicates that increased fertilization significantly affected nitrate accumulation in vegetable leaves, especially under high fertilization conditions. As fertilization increased from 150 kg·N / ha to 3600 kg·N / ha, the nitrate content in vegetable leaves gradually increased, suggesting that at higher fertilization levels, nitrogen supply in the substrate was excessive, nitrification was enhanced, leading to increased nitrate accumulation in both the substrate and the crop. According to the standards of the Food and Agriculture Organization of the United Nations and the World Health Organization, the acceptable daily intake of nitrates in food is 3.6 mg / kg body weight (as NO3-). - Based on a baseline of 0.5 kg of vegetables per day for a 60 kg adult, the nitrate content should be controlled below 432 mg / kg. Vegetables exceeding this standard should not be eaten raw, as excessive nitrate intake may pose a risk to human health. When the fertilizer application rate exceeds 2100 kg·N / ha, the nitrate content in vegetable leaves usually exceeds the food safety limit of 432 mg / kg due to the accumulation of nitrates in the substrate (Table 2). However, through appropriate processing methods, such as salting or cooking, the nitrate content in vegetables can be significantly reduced to meet food safety standards and still be safe for consumption.

[0069] Table 2 Evaluation Criteria for Nitrate Content in Vegetables

[0070] 4. The effect of fertilizer application rate on nitrogen atmospheric volatilization The results of ammonia volatilization showed that ( Figure 22 Under surface fertilization conditions, ammonia volatilization accounts for 21.7% to 30.1% of the applied fertilizer, with the volatilization rate decreasing slightly with increasing fertilizer application. Ammonia volatility increases significantly under high pH conditions. When the pH exceeds 8.5, the ammonia ionization equilibrium (NH4+)... + NH3+ H+ ) to the direction of free ammonia (NH3), making it easier to escape from water. Studies have shown that when the pH value reaches 9.3, the volatilization rate of ammonia increases significantly, and at pH 10, it almost exists in the gaseous state, and the volatilization rate reaches the maximum. Kroeker et al. further found that the volatilization of ammonia gas is very low at pH 7, but significantly increases at pH 9. Bouecke and Schindler's study also confirms this trend, pointing out that the volatilization rate begins to rise at pH 8.8, and reaches a peak at pH 10. Under the condition of buried pipe fertilization, the volatilization of ammonia gas is significantly reduced, and the volatilization ratio is only 0.6‰ to 0.3%, which can be almost ignored. This shows that buried pipe fertilization can effectively inhibit the volatilization of ammonia gas, significantly improve the utilization efficiency of nitrogen fertilizer, and reduce the potential pollution of ammonia gas to the atmospheric environment. In terms of nitrogen oxide emissions, although the amount of nitrogen oxide emissions increases with the increase of fertilizer application rate, the relative volatilization ratio is relatively stable, maintaining between 0.4% and 0.6%. There is a significant positive correlation between nitrogen fertilizer application rate and substrate nitrogen oxide (NO x ) emissions. Studies have shown that with the increase of nitrogen fertilizer application rate, the amount of NO x emissions in the substrate also increases accordingly. For example, the research team of Nanjing Agricultural University found through the estimation of global substrate nitrogen oxide emissions that the vegetable field substrate with high nitrogen fertilizer application rate is a hot spot area of substrate nitrogen oxide emissions. In addition, the research of the National Geographic Information System Engineering Technology Research Center pointed out that the total amount of NO x emissions from fertilized farmland in China in 2017 was 3741±0.39 Gg·N / year, accounting for 17.3% of the total emissions. These research results emphasize the importance of reasonable control of nitrogen fertilizer application rate for reducing substrate nitrogen oxide emissions. Compared with ammonia, the volatilization of nitrogen oxide is less sensitive to fertilizer application rate, but its cumulative effect cannot be ignored, especially under high fertilizer application rate conditions, which may have a potential impact on the atmospheric environment.

[0071] 5. Material flow accounting As shown in Figure 23 , under different fertilizer application rates, the proportion of nitrogen in the substrate retention, plant absorption and atmospheric volatilization is 71.0%~88.7%, 10.8%~26.7% and 0.5%~2.3% respectively. With the increase of fertilizer application rate, the retention proportion of nitrogen in the substrate gradually increases, while the plant absorption proportion gradually decreases, and the atmospheric volatilization proportion slightly decreases. The increase of nitrogen retention in the substrate reflects the accumulation of nutrients under high fertilizer application rate, and the decrease of plant absorption indicates that excessive fertilization exceeds the nutrient demand of plants. Although the nitrogen volatilization ratio in the atmosphere is low, the environmental risk (such as nitrogen leaching) caused by nitrogen accumulation under high fertilizer application rate still needs to be vigilant, and reasonable control of fertilizer application rate is crucial to improve the utilization rate of nitrogen.

[0072] The present application systematically studies the migration, retention, transformation and volatilization of regenerated liquid fertilizer in the substrate-atmosphere-plant system under different fertilizer application rates and water-fertilizer ratios through the application of regenerated liquid fertilizer in a two-way plant growing system, and focuses on the comprehensive effects of the regenerated liquid fertilizer on the physical and chemical properties of the substrate, plant growth and the environment. The main conclusions are as follows: The increase of fertilizer application rate significantly affects the pH, electrical conductivity, organic carbon and nitrogen accumulation of the substrate. When the fertilizer application rate is ≥1500 kg·N / ha / a, the pH of the substrate decreases significantly, and the EC increases significantly, approaching the critical value of international substrate salinization; the higher the fertilizer application rate, the more obvious the cumulative effect of organic carbon and nitrogen in the surface and upper layers of the substrate, and when the fertilizer application rate is ≥2100 kg·N / ha / a, there is a risk of leaching of nitrate nitrogen in the deep layer of the substrate (50-75 cm). The reasonable application of regenerated liquid fertilizer can significantly increase the protein and polysaccharide content of the leaves of the vegetables, but excessive fertilizer application (≥1500 kg·N / ha / a) inhibits the absorption of nutrients by the plants, and at the same time, leads to the nitrate content of the vegetables exceeding the first-level safety standard for edible use. The use of the device can be used for plant growing and nutrient assimilation of fecal pollution, and the fertilizer application rate needs to be controlled within 1500 kg·N / ha / a.

Claims

1. A modular, tandem, bidirectional plant planting device, characterized in that, It includes multiple bidirectional planting units connected in series, each bidirectional planting unit including at least one bidirectional planting unit bottle; the bottle has openings at the top and bottom, and the diameter of the top opening is larger than the diameter of the bottom opening; a perforated fertilizer tube is transversely arranged in the upper middle part of the bottle, and the fertilizer tube is equipped with multiple pressure-compensating drippers. The bottle body is provided with a planting layer substrate, a physical barrier layer, a water storage layer substrate, and a support layer from top to bottom.

2. The modular, tandem, bidirectional plant planting device according to claim 1, characterized in that, The planting layer substrate comprises the following components in parts by volume or mass: 40-70 parts coconut coir; 15-30 parts perlite; and 20 parts vermiculite.

3. The modular, tandem, bidirectional plant planting device according to claim 1 or 2, characterized in that, The water storage layer matrix comprises the following components in parts by volume or mass: 40-60 parts of expanded clay; 0-20 parts of loofah sponge; and 40-60 parts of rice husk charcoal.

4. The modular tandem bidirectional plant planting device according to any one of claims 1-3, characterized in that, The support layer includes sponge and / or rock wool; A funnel-shaped baffle is provided between the water storage layer matrix and the support layer; The bottom opening of the bidirectional planting unit bottle is provided with a push-button slot, and the push-button slot is provided on the support layer; The slotted columnar sponge is provided inside the slot.

5. The modular tandem bidirectional plant planting device according to any one of claims 1-4, characterized in that, The thickness ratio of the planting layer substrate, the water storage layer substrate, and the support layer is 1~3:3~10:1; The thickness of the planting layer substrate is 5cm to 15cm; the thickness of the water storage layer substrate is 15cm to 50cm; and the thickness of the support layer is 2cm to 7cm.

6. The modular, tandem, bidirectional plant planting device according to any one of claims 1-5, characterized in that, The diameter of the physical barrier layer is 1 / 3 to 4 / 5 of the diameter of the bottle body where it is set.

7. The modular tandem bidirectional plant planting device according to any one of claims 1-6, characterized in that, When each of the bidirectional planting units includes at least two bidirectional planting unit bottles, the bidirectional planting unit bottles are fixed in a modular fixing panel; The fertilizer tubes, which are installed throughout the body of the bidirectional planting unit, are connected to the main fertilizer tube via multi-port connectors to communicate with each other.

8. The modular series bidirectional plant planting device according to claim 7, characterized in that, A fixing ring is provided on the outer wall of the bidirectional planting unit bottle for fixing in the modular fixing panel.

9. The modular, tandem, bidirectional plant planting device according to any one of claims 1-8, characterized in that, Multiple bidirectional planting units are interconnected by vertical suspension.

10. The modular tandem bidirectional plant planting device according to any one of claims 1-9, characterized in that, Each of the two-way planting unit bottles has a fertilization tube that runs through it, and both ends of the tube are equipped with a suspension rope. All the suspension ropes are fixed to a suspension frame, which is used to fix the modular series-connected two-way plant planting device.

Images