Sandy substrate vegetation concrete for tung tree seed propagation and its application method

Abstract

This invention discloses a silty substrate vegetation concrete for tung tree seed propagation and its application method. The silty substrate vegetation concrete is made by mixing silty soil, cement, seawater, and fertilizer. By pouring this mixture into seedling tubes and planting tung tree seeds, an integrated concrete seedling tube structure is formed. This tube can be directly planted in outdoor wetlands for tung tree seed propagation, thus achieving seed germination, seedling propagation, and planting. This invention utilizes silty substrate vegetation concrete to construct an integrated concrete seedling tube structure, which has suitable strength, porosity, and density, improving the specific growth rate and survival rate of tung tree seedlings and greatly simplifying the tung tree seed cultivation process.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering materials technology, specifically relating to a mud-sand matrix vegetation concrete for seedling cultivation of tung trees and its application method. Background Technology

[0002] Mangroves are among the most productive marine ecosystems in the tropical and subtropical coastal ecotones, playing a vital role in purifying seawater, preventing wind and waves, maintaining biodiversity, and sequestering carbon. Because mangrove plants have specific environmental requirements, growing only on tidal flats between mean sea level (or slightly above) and the mean high tide level (or spring tide level), excessively high or low tidal inundation frequencies can lead to mangrove degradation, death, or difficulty in natural regeneration. Therefore, the cultivation of mangrove seedlings and the planting of mangrove forests are urgently needed.

[0003] Traditional mangrove afforestation methods mainly include natural seed hypocotyl afforestation, natural viviparous seedling afforestation, and artificial container seedling afforestation. Natural seed hypocotyl or viviparous seedling afforestation suffers from slow seedling development and low seedling survival rates. Artificial container seedling afforestation is prone to root damage during transplanting, leading to low survival rates and low stand retention. The current low survival rates in mangrove seedling cultivation and afforestation hinder the ecological restoration and recovery of mangroves, contributing to a series of ecological and economic problems, including declining yields of economic organisms in tidal flats, continuous outbreaks of diseases in tidal flat aquaculture, severe red tide disasters, increased typhoon losses, and reduced tourism resources. Therefore, it is particularly necessary to develop new methods for mangrove seed germination, rapid seedling propagation, and planting.

[0004] The tung tree (Tetracentron sinense) is an evergreen shrub or small tree belonging to the genus *Tetracentron sinense* in the family Myrsinaceae. It is the second most widely distributed mangrove species in China, after *Avicennia marina*. Tung trees can be found in silt, muddy, and sandy beaches, and are considered early to mid-stages of mangrove succession. They are mostly distributed on the outer edges of mangrove forests, reaching heights of 4-5 meters in tropical regions. The Luoyang River estuary in Quanzhou, Fujian Province, is the northernmost natural Tung tree community globally. Tung trees thrive in sunlight, are tolerant of low temperatures and seawater inundation, and possess strong salt tolerance. They also provide good wind and wave protection, making them a key species for coastal protection forests. The bark and leaves of the tung tree have medicinal uses, serving as an adjunct treatment for asthma, diabetes, inflammation, and rheumatism. Tung trees are cryptoviviparous mangroves, reproducing sexually through seeds. Flowering occurs from December to April of the following year, and the fruit matures from August to November. The cryptovivic capsule is cylindrical, crescent-shaped, and tapering at the apex, measuring 5-10 cm in length. The hypocotyl never breaks through the pericarp during development, and after ripening, it floats on water. The seeds are similar in shape to the fruit, weighing approximately 0.5-1.5 g. Because natural seeds of the *Tung Tree* lack a hypocotyl and viviparous seedlings are too small, they are unsuitable for afforestation using natural seeds or hypocotyls. Traditionally, artificial container seedlings are used for afforestation: *Tung Tree* seeds are first cultivated in seedbeds, then transplanted into nutrient bags for further cultivation. After reaching suitable seedling size, they are then transplanted to coastal wetlands and tidal flats. However, the root system of artificially containerized *Tung Tree* seedlings is easily damaged during transplanting, leading to low survival and retention rates. Preliminary experiments have shown that sandy soils are suitable for cultivating artificially containerized *Tung Tree* seedlings. Therefore, it is particularly necessary to develop new methods for *Tung Tree* seed germination, rapid seedling propagation, and planting. Summary of the Invention

[0005] The purpose of this invention is to provide a mud-sand substrate vegetation concrete for tung tree seed propagation and its application method. It is a new model for tung tree seed germination, rapid seedling propagation and planting application. It uses commonly available raw materials to prepare a structurally integrated and performance-stable concrete seedling tube. This seedling tube can be directly inserted into the wetlands of the wild for tung tree seed propagation, thereby realizing the integrated function of seed germination, seedling propagation and planting application, and can significantly improve the rate and survival rate of tung tree seedling cultivation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A type of silty soil substrate vegetation concrete for tung tree seedling cultivation is composed of silty soil, cement, seawater, and fertilizer. Based on the mass of the silty soil, the cement content in the vegetation concrete is 4.4-9.2%, the water-cement ratio is 2.52-5.10, and the fertilizer content is 0.5‰. Preferably, by weight, the amount of silty soil is 1017-1400 parts, the amount of cement is 56.5-118 parts, the amount of seawater is 181-378 parts, and the amount of fertilizer is 0.53-0.68 parts.

[0008] Specifically, when the cement content is 6.8%, the sand content is 25-80%, and the water-cement ratio is 2.52-5.10, the resulting mud-sand matrix vegetation concrete has a compressive strength of 1.267-2.001 MPa, a porosity of 22.11-32.98%, and a density of 1345-1635 kg / m³. 3 When the sand content is 66.6%, the water-cement ratio is 3.2, and the cement content is 4.4-9.2%, the compressive strength of the resulting mud-sand matrix vegetation concrete is 0.680-2.572 MPa, the porosity is 27.79-31.44%, and the density is 1543-1635 kg / m³. 3 .

[0009] Furthermore, the silty soil is made from a mixture of marine mud and marine sand, with a sand content of 25-80%. Preferably, by weight, the silty soil contains 280-763 parts marine mud and 254-1120 parts marine sand, with a sand content of 66.6%.

[0010] Furthermore, the particle size of the marine mud and marine sand is 0.5~1.0 mm.

[0011] Furthermore, the fertilizer has a total nutrient content of 24%, wherein the ratio of N, P2O5, and K2O is 16:5:3%.

[0012] The method for cultivating tung tree seeds using the aforementioned mud-sand matrix vegetation concrete involves mixing muddy soil, cement, seawater, and fertilizer in a specific ratio, pouring the mixture into a seedling tube, pre-forming it into a compact for one day to obtain mud-sand matrix vegetation concrete, then planting a tung tree seed in the seedling tube at a distance of 3-5 cm from the concrete surface, curing it for 7 days, and finally directly planting the integrated concrete seedling tube onto the tidal flat wetland to achieve seed germination, seedling propagation, and planting application of tung trees.

[0013] Furthermore, the seedling tube is a bamboo tube, plastic tube, ceramic tube, or metal tube with openings at both ends and an inner diameter of 7-9 cm and a length of 25-30 cm.

[0014] The silty substrate vegetation concrete of this invention has suitable strength and density, which not only helps seeds and seedlings to adhere and resist lodging, but also prevents the loss of seedling substrate, seeds and seedlings. Its suitable porosity can also effectively improve the water permeability and air permeability of the substrate during seed germination, seedling propagation and planting. Adding fertilizer can make up for the lack of nitrogen, phosphorus and potassium in silty soil raw materials, and improve the specific growth rate and survival rate of seedlings. The integrated structure constructed by concrete and seedling tubes can also mitigate the erosion of ocean waves. Moreover, this invention is simple to operate, has low production cost, and can generate good social, ecological and economic benefits.

[0015] The beneficial effects of this invention are as follows:

[0016] 1. This invention adjusts the sand content of the silty soil raw material to combine the advantages of sandy and muddy soils, improving the permeability and aeration of the substrate soil. Furthermore, by using soil testing and fertilization methods, fertilizers are added to the vegetation concrete according to the nutritional needs of tung tree seedlings to compensate for the lack of nitrogen, phosphorus, and potassium in the silty soil raw material, improve the nutritional structure of the substrate soil, and provide a good habitat for tung trees.

[0017] 2. The present invention uses a concrete seedling tube formed by solidifying silty soil to create a structurally integrated and stable structure. This can effectively improve the survival rate of tung tree plants and protect tung tree plants planted on coastal wetland tidal flats from wave erosion and aquatic animal grazing. Its high strength and high density can also help to mitigate wave erosion.

[0018] 3. The silty soil of this invention, after being solidified, produces vegetation concrete with suitable strength and density, which can effectively improve the fixation of the seedling cultivation substrate. It can not only help the seeds and seedlings to adhere and resist lodging, but also prevent the loss of seedling substrate, seeds and seedlings, and avoid the small tung tree seeds and seedlings from being washed away by the waves due to the periodic tidal erosion.

[0019] 4. The vegetation concrete made from the silty soil of this invention has a suitable porosity, which can effectively improve the water permeability and air permeability of the seedling cultivation substrate, improve the efficiency of seed germination, seedling propagation and afforestation, and avoid seedlings dying due to lack of oxygen caused by buried aerial roots and reduced water permeability and air permeability, which would make it difficult to preserve tung tree seedlings.

[0020] 5. This invention is a new afforestation model that integrates natural seed germination, rapid propagation of container seedlings, and transplant-free planting in the wild. It can realize three functions—seed germination, seedling propagation, and planting—using the same seedling tube. It overcomes the defects of natural seeds and seedlings of Tung tree that are too small to withstand the impact of sea waves, and also avoids the problems of low survival rate and low retention rate of Tung tree container seedlings when transplanted to coastal wetland tidal flats due to root damage. It can significantly improve the cultivation rate and survival rate of Tung tree seedlings. Attached Figure Description

[0021] Figure 1 This is a picture of actual tung tree seeds.

[0022] Figure 2 This is a picture of a tung tree seedling. Detailed Implementation

[0023] A method for seed propagation of Tung tree using the aforementioned muddy substrate vegetation concrete involves mixing muddy soil and cement for 1 minute, then adding fertilizer and seawater and mixing until uniform to form a concrete slurry. This slurry is then poured into a seedling tube with openings at both ends, an inner diameter of 7-9 cm, and a length of 25-30 cm. After pre-forming for 1 day, a muddy substrate vegetation concrete is obtained. Subsequently, a Tung tree seed is implanted in the seedling tube at a distance of 3-5 cm from the concrete surface. After continuing to cultivate for 7 days, a structurally integrated and stable concrete seedling tube is formed. This concrete seedling tube can be directly planted in wild tidal flats and wetlands for Tung tree seed propagation, thereby achieving three functions: seed germination, seedling propagation, and planting application.

[0024] Based on the quality of silty soil, the cement content in the concrete slurry is 4.4-9.2%, the water-cement ratio is 2.52-5.10, and the fertilizer content is 0.5‰.

[0025] The silty soil is made from a mixture of marine mud and marine sand, with a sand content of 25-80%. The particle size of both the marine mud and marine sand is 0.5-1.0 mm.

[0026] The fertilizer has a total nutrient content of 24%, with N, P2O5 and K2O in a ratio of 16:5:3%; the fertilizer can be added directly or prepared into an aqueous solution for use.

[0027] The seedling tube can be one of bamboo tube, plastic tube, ceramic tube or metal tube.

[0028] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0029] Raw material selection:

[0030] The tung tree seeds used weigh approximately 0.5 to 1.5 g, are 3.5 to 4.5 cm long, and have a diameter of approximately 0.5 cm.

[0031] The cement used is PS 32.5 and PS 32.5 slag silicate cement;

[0032] The seawater comes from the natural seawater (salinity 20~33‰) at the mouth of Jinjingxi River on the Jinjiang Campus of Fuzhou University.

[0033] The silty soil is prepared by mixing marine mud and marine sand in different proportions according to the sand content index requirements. The marine mud used is silt from the understory of the natural mangrove community in Quanzhou Bay, Fujian Province. It is water-milled and screened to a particle size of 0.25~0.5mm, 0.5~1.0mm, 1.0~1.5mm and 1.5~2.0mm, and then drained for later use. The marine sand used is natural marine sand that has been water-milled and screened to a particle size of 0.35~0.45mm, 0.5~1.0mm, 1.0~1.5mm and 1.5~2.0mm, and then drained for later use.

[0034] The fertilizer contains 24% total nutrients and is compounded according to the N:P2O5:K2O ratio of 16:5:3%. The fertilizer dosage is 0.5‰ of the dosage for sandy soils. It can be added directly or prepared into an aqueous solution for use.

[0035] Unless otherwise specified, the test methods are all conventional methods in this field. For example, refer to the "CECS 361-2003 Technical Specification for Application of Ecological Concrete" or the "JGJ51-2002 Technical Specification for Lightweight Aggregate Concrete". When performing performance tests, the concrete is demolded after 28 days of standard curing and made into standard test blocks with a size of 100 mm × 100 mm × 100 mm for testing.

[0036] Germination rate (%): refers to the percentage of seeds that have germinated out of the total number of valid test seeds. Statistics are started when the seeds have grown two cotyledons.

[0037] Specific growth rate (cm / d): Statistics begin when the seed germinates and has two true leaves, and are calculated using the following formula:

[0038] ,

[0039] In the formula: V -Specific growth rate (cm / d); h 1 -Initial plant height (cm); h 2 - Final plant height (cm); t 2 -t 1 - Plant growth time difference (d). Example

[0040] 1. The Influence of Marine Sediment Particle Size on Concrete Performance

[0041] According to the formula in Table 1, the marine mud and cement of different particle sizes are mixed for 1 minute, and then seawater is added and stirred until uniform to make concrete slurry. Then it is poured into the seedling tube and pre-formed into a blank under normal temperature and pressure for 1 day to make mud-based vegetation concrete. After standard curing for 28 days, it is demolded and its performance is tested.

[0042] Table 1. Influence of marine mud particle size on concrete performance

[0043]

[0044] As shown in Table 1, with a water-cement ratio of 4.6 and a cement content of 7.5%, the porosity of the concrete increases and the compressive strength and density decrease with the increase of the marine mud particle size. When the marine mud particle size is 0.5~1.0 mm, the concrete porosity is 28.76% and the compressive strength is 1.039 MPa, and its comprehensive performance can initially meet the requirements for seedling cultivation of tung tree seeds.

[0045] 2. The Influence of Sea Sand Particle Size on Concrete Performance

[0046] According to the formula in Table 2, sea sand of different particle sizes and cement are mixed for 1 minute, then seawater is added and mixed until uniform to make concrete slurry. Then it is poured into seedling tubes and pre-formed into blanks under normal temperature and pressure for 1 day to make sandy vegetation concrete. After standard curing for 28 days, it is demolded and its performance is tested.

[0047] Table 2. Effects of sea sand particle size on concrete performance

[0048]

[0049] As shown in Table 2, with a water-cement ratio of 3.5 and a cement content of 6.25%, the porosity of the concrete increases and the compressive strength and density decrease with the increase of the sea sand particle size. When the sea sand particle size is 0.5~1.0 mm, the concrete porosity is 33.46% and the compressive strength is 1.209 MPa, and its comprehensive performance can initially meet the requirements for seedling cultivation of tung tree seeds.

[0050] 3. The Influence of Sand Content and Water-Cement Ratio on Concrete Performance

[0051] According to the formula in Table 3, mix different proportions of silty soil and cement for 1 minute, then add seawater and mix until uniform to make concrete slurry. Then pour it into the seedling tube and pre-form it into a blank under normal temperature and pressure for 1 day to obtain silty substrate vegetation concrete. After standard curing for 28 days, demold it and conduct performance tests.

[0052] Table 3. Effects of sand content and water-cement ratio on concrete properties

[0053]

[0054] As shown in Table 3, compared with the lower porosity and compressive strength of the control example silty soil, the cement-cured concrete exhibited significantly higher porosity and compressive strength. With a fixed cement content of 6.8%, the ecological concrete showed the highest compressive strength and density, and the lowest porosity, at a water-cement ratio of 2.52 and a matrix sand content of 80%. Conversely, the ecological concrete showed the lowest compressive strength and density, and the highest porosity, at a water-cement ratio of 5.10 and a matrix sand content of 25%.

[0055] 4. The effect of cement admixture on concrete performance

[0056] According to the formula in Table 4, mix the sandy soil and cement for 1 minute, then add seawater and mix until uniform to make concrete slurry. Then pour it into the seedling tube and pre-form it into a blank under normal temperature and pressure for 1 day to obtain sandy substrate vegetation concrete. After standard curing for 28 days, demold and conduct performance tests.

[0057] Table 4. Effect of Cement Admixture on Concrete Performance

[0058]

[0059] As shown in Table 4, compared with the lower porosity and compressive strength of the control example sandy soil, the porosity, compressive strength, and density of the cement-cured concrete all significantly increased with increasing cement content. The mathematical expressions for the correlation between concrete porosity, compressive strength, density, and cement content are as follows when the matrix sand content is 66.6%, the water-cement ratio is 3.2, and the cement content is 4.4–9.2%:

[0060] The relationship between porosity Y and cement content X is: Y = -0.7775X + 34.917, R² = 0.9976;

[0061] The relationship between compressive strength Y and cement content X is: Y = 0.3973X - 1.0171, R² = 0.9939;

[0062] Relationship between density Y and cement admixture X: Y = 0.3968X 2 +13.77X+1474.9, R²=0.9997.

[0063] In summary, silty soils, due to their low compressive strength, cannot withstand the erosion of ocean waves and tides, and their low porosity results in insufficient water and air permeability. However, the compressive strength of these soils can be greatly improved by using cement as a cementing material, and the resulting concrete can effectively resist the erosion of ocean waves and tides. Furthermore, the appropriate porosity of concrete can effectively improve the water and air permeability of the substrate, meeting the needs of tung tree seed germination, seedling propagation, and planting under different tidal conditions.

[0064] Application Examples: Application of Concrete Seedling Pipes

[0065] According to the formulas in Tables 5 and 6, the silty soil and cement are mixed for 1 minute respectively. Then, fertilizer and seawater are added one after another and mixed until uniform to make concrete slurry. The slurry is then poured into plastic seedling tubes with open ends, an inner diameter of 7-9 cm and a length of 25-30 cm. After pre-forming the slurry for 1 day under normal temperature and pressure, silty soil substrate vegetation concrete is obtained. Then, tung tree seeds are planted in the seedling tubes at a distance of 3-5 cm from the concrete surface. After continuing conventional maintenance for 7 days, a structurally integrated and stable concrete seedling tube is formed. The seedling tubes are then directly planted in the tidal flat wetland at the Jinjiang Campus of Fuzhou University for germination, seedling propagation and planting of tung tree seeds.

[0066] Table 5. Effects of water-cement ratio in concrete on specific growth rate and survival rate of *Aristolochia debilis* seedlings.

[0067]

[0068] As shown in Table 5, the specific growth rate and survival rate of *Tung Blossom Tree* seedlings were both low when the sandy soil was not solidified with cement. Adding fertilizer could compensate for the deficiencies in nitrogen, phosphorus, and potassium in the sandy soil, thus improving the specific growth rate and survival rate of the seedlings. This may be because the sandy soil has low compressive strength and porosity when not solidified with cement, making it difficult to provide a permeable and aerated substrate environment. Furthermore, the planting substrate is easily lost, making it difficult for *Tung Blossom Tree* seedlings to grow stably under the scouring of ocean waves.

[0069] Meanwhile, as shown in the table, when the cement content is fixed at 6.8% and the fertilizer content at 0.5‰, the specific growth rate of *Tung Blossom Tree* seedlings first increases and then decreases as the water-cement ratio decreases. At a water-cement ratio of 3.2, the specific growth rate of *Tung Blossom Tree* seedlings reaches 0.225 cm / d, and the survival rate reaches 100%, indicating the optimal effect. The mathematical expression for the correlation between the specific growth rate of *Tung Blossom Tree* seedlings and the water-cement ratio of ecological concrete when the cement content is 6.8%, the fertilizer content is 0.5‰, and the water-cement ratio is 2.8~4.7 is as follows:

[0070] The specific growth rate Y is related to the water-to-gel ratio X: Y = -0.0352X 2 +0.2415X-0.1936, R²= 0.9624.

[0071] Table 6. Effects of cement content in concrete on the specific growth rate and survival rate of *Aristolochia debilis* seedlings.

[0072]

[0073] As shown in Table 6, when the water-cement ratio is 3.2 and the fertilizer content is 0.5‰, the specific growth rate first increases and then decreases with increasing cement content. This is because a cement content of 9.2% leads to an increase in the pH value of the concrete, which cannot guarantee the normal environmental requirements for the germination of tung tree seeds and the propagation of seedlings. The mathematical expression for the correlation between the specific growth rate of tung tree seedlings and the cement content of ecological concrete when the water-cement ratio is 3.2, the fertilizer content is 0.5‰, and the cement content is 4.4~9.2% is as follows:

[0074] Relationship between specific growth rate Y and cement content X: Y = -0.013X 2 +0.1606X-0.2697, R²= 0.9938.

[0075] In contrast, in Example 2, the tung tree seeds in the sandy soil seedling tubes only began to germinate on the 17th day after planting, with a germination rate of 85% on the 25th day. It was also found that 60% of the tung tree seeds were lost due to erosion by ocean waves. However, in Example 2, the tung tree seeds in the concrete seedling tubes did not show any loss, and they began to germinate on the 13th day after planting, with a germination rate of 100% on the 19th day.

[0076] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A sand matrix vegetated concrete for raising Jatropha curcas seeds, characterized by: The vegetation concrete is composed of sandy soil, cement, seawater and fertilizer; wherein, based on the mass of the sandy soil, the cement content in the vegetation concrete is 4.4-9.2%, the water-binder ratio is 2.52-5.10, and the fertilizer content is 0.5‰; the sandy soil is made of sea mud and sea sand mixed together, and the sand content is 25-80%; The total nutrient content of the fertilizer is 24%, wherein the ratio of N, P2O5 and K2O is 16:5:3; The particle size of the sea mud and sea sand is 0.5-1.0 mm; The method for cultivating tung oil tree seeds by using the sandy matrix vegetation concrete is as follows: the sandy soil, cement, seawater and fertilizer are mixed in proportion, and then poured into a seedling pipe to pre-cure for 1 day to obtain the sandy matrix vegetation concrete; then, tung oil tree seeds are planted in the seedling pipe at a distance of 3-5 cm from the surface of the concrete, and cured for 7 days; finally, the integrated structure concrete seedling pipe is directly planted on the tidal wetland to realize the seed germination, seedling cultivation and planting application of the tung oil tree. The seedling pipe is a bamboo pipe, plastic pipe, ceramic pipe or metal pipe with open ends, an inner diameter of 7-9 cm and a length of 25-30 cm.

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