Fertilizing cylinder for cultivating nori and fertilizing method for cultivating nori

Abstract

To provide a fertilizing cylinder for culturing Nori capable of supplying nitrogen, phosphorus, etc., necessary for the growth of Nori in an economical and environment-friendly manner in relation to the supply of nutrient salts in the culturing of Nori by a support fence system and to provide a fertilizing method for culturing Nori.SOLUTION: In a fertilizing cylinder for culturing Nori, there is one hole 3, 5 at each of the top and bottom of the fertilizer barrel 10, when the tide level drops and the cylinder becomes exposed above a sea level, air enters through the hole 3 at the top of the cylinder, and the aqueous solution formed by dissolving a fertilizer material 6 in seawater that has entered the barrel is discharged through hole 5 at the bottom of the cylinder, wherein the size of the lower hole 5 is set at a height at which the surface tension of the aqueous solution when it exits from the lower hole 5 of the fertilizing cylinder matches the water pressure of the aqueous solution inside the fertilizer cylinder, and at which the aqueous solution stops discharging from the lower hole 5 of the fertilizer cylinder. Also there is provided a fertilizing method for culturing Nori using the fertilizing cylinder for culturing Nori.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention mainly relates to the efficient supply of nutrients for laver cultivation carried out mainly off the coasts of Japan, South Korea, and China. It utilizes products made from ammonium sulfate, steel slag, and scale, which are co-products in the steelmaking process, as raw materials for fertilizers. While taking into account the marine environment, it relates to a technology for achieving carbon dioxide fixation and the development of the fishery industry through the cultivation of seaweeds.

Background Art

[0002] Ammonium sulfate generated in the steel manufacturing process has long been used as a raw material for nitrogen fertilization in the Japanese laver cultivation industry. Slag contains minerals such as iron, magnesia, and silica, which are effective for the biological environment. For example, as a mineral source for marine environment restoration, or especially when it contains phosphoric acid like dephosphorized slag, it is known to have high utilization value as a fertilizer and is used by tens of thousands of tons annually by the entire agricultural community and fertilizer manufacturers. Since these raw materials are linked to the cultivation of land and sea plants and seaweeds, their role as fertilizers for promoting "blue carbon" and "green carbon" has been attracting attention in recent years.

[0003] On the other hand, globally, the rise in seawater temperature due to global warming and the decrease in seaweeds due to damage from pests, "seashore burning," have become problems, and efforts such as seaweed bed creation have been carried out by industry, government, and academia. However, although only about 0.8% of marine organisms live in the coastal shallow sea area, which is only a small part of the entire sea surface, 80% of them live there. Appropriate supply of nutrients and provision of a place are necessary. However, among the nutrients, phosphorus and nitrogen have also been factors causing excessive growth of phytoplankton. Therefore, in the coastal shallow sea areas of Japan, total regulations on nitrogen and phosphorus in seawater have been established. For laver farmers, in addition to the rise in seawater temperature, they are also adversely affected in terms of both production volume and quality due to insufficient nitrogen and phosphorus nutrients.

[0004] The reasons why steel slag is effective as a silicate fertilizer and a marine environment restoration material are as follows: SiO2 forms a complex oxide with CaO, making it easy for the silicate component to elute; most of the iron exists in the divalent form, which is effective for the activities and growth of organisms, rather than the trivalent form that is abundant in nature. Regarding the alkali water problem caused by the inevitably contained unreacted CaO (hereinafter referred to as free lime), by neutralizing it with carbon dioxide gas and reacting it with corrosive soil to produce iron fulvate, it is possible to provide a safe iron supply material. On the other hand, ammonium sulfate produced in the process of removing hydrogen sulfide from coke ovens has long been widely used as "ammonium sulfate" in the agricultural field. In the fisheries field, in the 1970s, there was literature information such as its use in Porphyra yezoensis in Tokyo Bay. However, in 1970, the Water Pollution Control Law was enacted, and ammonium sulfate was designated as a harmful substance (Article 2 of the Water Pollution Control Law, Article 2 of the Enforcement Order, and Article 1 of the Ordinance for Determining Wastewater Standards). Since it generates ammonia and sulfurous acid gas harmful to the human body by thermal decomposition and requires skill in handling, currently, although it is experimentally used in fisheries experimental stations, etc., in some areas where seaweed farming is prosperous, such as Ariake Sea and Seto Inland Sea, except for the exceptional fertilization use by fishermen, it is not used in the sea area.

[0005] Japan's seaweed farming industry effectively utilizes the nutrients in the sea area and plays an important role in both food production and marine environmental conservation. According to the Marine Fisheries Production Statistics Survey of seaweed farming mainly for food (Fisheries Agency http: / / www.maff.go.jp / j / tokei / kouhyou / kaimen_gyosei / index.html), it is roughly classified into four types: laver, wakame, kombu, and mozuku. In terms of production volume, laver, wakame, kombu, and mozuku are in descending order, with a total of about 400,000 - 500,000 tons per year. The laver with the highest production volume in laver farming is black laver. Among black lavers, the one with the highest production volume is Pyropia yezoensis, a red algae seaweed classified in the genus Pyropia of the Bangiaceae family. It grows naturally on the Pacific coast north of Fukushima Prefecture and is cultivated throughout Japan as a raw material for sheet laver.

[0006] The cultivation of these seaweeds also plays a role in artificially taking up carbon dioxide from the sea area, and has attracted attention in recent years as a carbon offset method. Efficiently fertilizing the cultivated seaweeds with ammonium sulfate and steel slag means removing carbon dioxide from seawater without causing water pollution by using by-products of the steel industry, which is an important issue from both the perspectives of reducing Japan's carbon dioxide emissions and supporting the seaweed cultivation industry.

[0007] For example, Patent Document 1 discloses a cylindrical container with a pore diameter of 2 to 20 mm, a ratio of the total pore area to the total outer surface area of the cylindrical container of 0.001 to 0.1, and at least 4 or more pores, having an inner diameter of 50 to 250 mm and a length of 500 to 2,000 mm, having an opening / closing part on at least one side of the cylinder, and a fertilizer filling container with a pore diameter of 0.1 to 1 mm, a ratio of the total pore area to the total outer surface area of the container of 0.000001 to 0.001, and at least 5 or more pores. A seaweed cultivation fertilization container with a fertilizer filling container installed inside is disclosed. If the number of pores is large, it will be time-consuming for maintenance and also costly to manufacture. Patent Document 2 states that for the a* value and b* value measured by the L*a*b* color system color determination method, when the a* value is 0 or less and the b* value is 3 to -1, it is determined as a combined deficiency of iron and nitrogen, and a method for preventing and recovering the discoloration of nori thallus, characterized by fertilizing iron and nitrogen components to the nori cultivation farm, is described in Claim 1 or 2, but there is no description of a specific container, and there is only a description of simply fertilizing nitrogen, without any description regarding concentration control, etc. Patent Document 3 describes a method for manufacturing a fertilizing material and a method for suppressing the discoloration of seaweed, characterized by using a nitrogen-containing waste liquid discharged during the extraction of valuable metals or the cleaning of semiconductor manufacturing equipment as a raw material.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention relates to the supply of nutrients in the cultivation of laver using a support fence such as the laver building method, and provides a fertilization container for supplying nitrogen, phosphorus, etc. necessary for the growth of laver in an economical and environmentally considerate manner, and a method for using the same.

Means for Solving the Problems

[0010] The fertilization container of the present invention and the method for fertilizing laver using the fertilization container, which are made to solve the above problems, are (1) A fertilization cylinder for fertilizing in laver cultivation, wherein one hole is opened at each of the upper and lower parts of the fertilization cylinder, the inside of the fertilization cylinder can be filled with a fertilizer agent that contributes to the growth of laver, and when the fertilization cylinder is exposed above the sea surface as the tide level drops, air enters through the hole at the upper part of the fertilization cylinder, and an aqueous solution formed by dissolving the fertilization material in the seawater that has invaded the inside of the fertilization cylinder is discharged from the hole at the lower part of the fertilization cylinder. The size of the hole at the lower part is such that the surface tension when the aqueous solution exits from the hole at the lower part of the fertilization cylinder is equal to the water pressure of the aqueous solution inside the fertilization cylinder, and the size is such that the discharge of the aqueous solution from the hole at the lower part of the fertilization cylinder stops. The aqueous solution diffuses around due to the change in the tide level, and a fertilization cylinder for laver cultivation characterized by fertilizing the laver net. (2) The fertilization cylinder for laver cultivation according to claim 1, characterized in that a transparent material is used for the lid of the fertilization cylinder so that the usage amount of the fertilizer agent can be easily confirmed. (3) The fertilization cylinder for laver cultivation according to (1) or (2), characterized in that a metal tube tin material is used for the body of the fertilization cylinder in order to dissolve a trace amount of metallic iron in the fertilizer agent. (4) A method for fertilizing laver cultivation, characterized by filling the fertilization cylinder for laver cultivation according to (1) with the fertilizer agent, installing it at the same height as the laver net on the support on which the laver net is installed, and the fertilizer agent does not elute during low tide, and discharging the aqueous solution during immersion. (5) The method for fertilizing laver cultivation according to (4), characterized in that a co-product containing one or more of ammonium sulfate, steelmaking slag, steelmaking slag containing phosphoric acid, iron oxide, and iron filings generated in the steel industry is used as the fertilizer.

Advantages of the Invention

[0011] According to the present invention, when the tide goes out, the fertilizer and its aqueous solution are retained in the container, and when immersed, the aqueous solution is discharged, and a trace amount of nutrients is fertilized. Therefore, compared with the method of constantly putting the fertilizer into seawater due to tidal currents or the like at present, laver cultivation can be carried out with a much smaller amount of fertilizer. By reducing the amount of fertilizer applied, it is not only economical but also the environmental load on the surrounding sea area is extremely small, so the risk of red tide damage is also small. When using co-products from steelworks instead of imported products as fertilizers, it can also contribute to reducing the amount of carbon dioxide generated.

[0012] Also, compared with the conventional fertilization method, large machinery is not required, and it is only necessary to install PVC or resin pipes, metal pipes and caps, so the equipment investment is small. In addition, since the elution amount is extremely small, it is only necessary to replace the fertilization cylinder and add fertilizer once every few days. For ammonium sulfate and iron phosphate supply agents used as fertilizers, since they are produced as co-products from steelworks, both the quantity and quality can be managed. Furthermore, the laver (seaweed) obtained by the present invention will remove carbon components from seawater, so the effect as a blue carbon method can be expected for the steel industry.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4-1

Figure 4-2

Figure 5

Figure 6-1

Figure 6-2

Figure 6-3

Figure 6-4

Figure 6-5

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0014] The main object of the present invention is to quickly and economically supply a fertilizer that contributes to the growth of nitrogen and seaweed to the seaweed cultivated in a support fence that mainly requires nitrogen and the like. As the candidate nitrogen source, it is preferable to use ammonium sulfate generated in the iron-making process, urea or ammonium nitrate that is a raw material of chemical fertilizers, etc., but it is not limited to those produced from the iron-making process.

[0015] Figure 1 is a conceptual diagram of an example of a fertilizer cylinder suitable for carrying out the invention of the present application.

[0016] First, put the fertilizer material 6 into the fertilizer cylinder body 1, and fit the upper lid 2 and the lower lid 4, each with a small hole (hole 3 in the upper lid and hole 5 in the lower lid) at both ends of the fertilizer cylinder body 1 onto the fertilizer cylinder body 1 to form the fertilizer cylinder 10. As shown in Figure 2, fix this fertilizer cylinder 10 to the pile 21 of the support fence for laver cultivation so that the lower end of the fertilizer cylinder 10 is at the same height as the lower end part with the laver net 20 stretched. Laver can withstand not being in contact with seawater for a certain period of time without problem, while phytoplankton and the like cannot withstand exposure to air and will die. Therefore, the laver net 20 is generally installed at a height where the laver dries out for a certain period of time between high tide and low tide. On the other hand, while the laver is drying out, it cannot absorb the nutrients in the seawater. Therefore, fertilizing during low tide is inefficient because it will be consumed by phytoplankton. So, it is economical to set the height of the fertilizer cylinder 10 such that the position where the lower fertilizer material 6 elutes is at the same height as the height of the laver net 20 (for example, within the general range of the lower end position of the laver net shown in Figure 4-1 described later), so that the fertilizer material 6 does not come out during low tide. The upper lid 2 of the fertilizer cylinder 10 is removable and is shaped such that solids containing nitrogen (such as ammonium sulfate, urea, ammonium nitrate, etc.) can be put in as the fertilizer material 6. During low tide, a nitrogen source can be additionally replenished into the cylinder. The fertilizer cylinder 10 does not necessarily have to be cylindrical. As long as there is one hole at each of the top and bottom, it can be a polygonal cylinder such as a square or triangular cylinder, and it does not have to have a constant shape in the height direction.

[0017] When the fertilizer cylinder 10 is immersed in seawater as the tide level rises, air escapes from the hole 3 in the upper lid, and seawater fills the fertilizer cylinder 10. A saturated aqueous solution containing the nutrient 11 in which the solid containing nitrogen, which is the fertilizer material 6, has dissolved diffuses little by little to the outside from the hole 3 in the upper lid and the hole 5 in the lower lid of the fertilizer cylinder 10, and the laver on the laver net around the cylinder absorbs the dissolved nitrogen of the nutrient 11.

[0018] When the fertilizer application cylinder 10 is exposed above the sea surface as the tide level drops, air enters through the hole 3 in the upper lid, and the saturated aqueous solution in which the solid containing nitrogen, the fertilizer material 6, is dissolved is discharged from the hole 5 in the lower lid 4 of the fertilizer application cylinder 10. However, as shown in Fig. 3, at the height where the surface tension when the saturated aqueous solution exits from the hole 5 in the lower lid and the water pressure of the saturated aqueous solution inside the fertilizer application cylinder 10 are in agreement, the discharge of the saturated aqueous solution from the hole 5 in the lower lid of the fertilizer application cylinder 10 stops. In this case, as shown in Fig. 2 and described above, by installing the lower part of the fertilizer application cylinder 10 at the same height as the lower end part in the state where the seaweed net 20 is stretched in the middle of the ebb and flood zones, it is possible to prevent wasteful elution during low tide. However, if the height is finely adjusted considering the influence of local waves, there will be even less waste.

[0019] This is because when the liquid flows out from the hole 5, the pressure difference between the inside and outside of the hole 5 balances the surface tension of the liquid. The relationship between the curvature radius of the liquid surface and the internal and external pressure difference is determined by the Young-Laplace equation. If the internal and external pressure difference is ΔP (Pa), the surface tension of the liquid is σ (N / m), and the curvature radius is r (m), then ΔP = 2σ / r. To have the liquid flow out from a hole with radius R, an internal and external pressure difference of ΔP = 2σ / R or more is required. As shown in Fig. 3 mentioned above, the smaller the R, the more the internal residual amount of the saturated aqueous solution when the cylinder is exposed above the sea surface. The remaining solid crystals dissolve again until they become a saturated aqueous solution when immersed in seawater due to the rising tide level. After the tide level drops and the aqueous solution of ammonium sulfate stops flowing out from the lower part of the cylinder, the dissolution of the solid crystals stops again. For example, in a fertilizer application test where 5 kg of ammonium sulfate was put into a cylinder with a hole of φ0.8 mm, a cylinder diameter of φ100 mm, and a height of 500 mm, the average remaining amount of 30 cylinders was about 50% after 30 hours. Since the seaweed aquaculture farm is extensive and a large number of fertilizer application cylinders 10 are installed, although there are variations in the local sea area, in the case of the fertilizer application cylinder 10 of the above-mentioned size, it has been found that stable nitrogen supply is possible by replenishing the fertilizer 6 once every two days.

[0020] On the one hand, when a fertilizer cylinder with a plurality of holes in the lower lid was immersed in seawater, there was a problem that the dissolution rate changed depending on the remaining amount of the fertilizer agent. This is presumably because when the remaining amount of the fertilizer agent decreased and only liquid remained inside the fertilizer cylinder, air entered through some of the plurality of holes in the lower lid, and seawater containing the fertilizer agent flowed out from the remaining holes. Also, when holes were opened only in either the upper lid or the lower lid, the fertilizer agent remained until the end. Therefore, based on FIG. 3 and the above findings, in order to efficiently let the internal saturated aqueous solution flow out to the outside, when the holes in the upper lid are made the same size as the holes in the lower lid one by one, seawater enters through the holes in the upper lid, and the saturated aqueous solution flows out from the holes in the lower lid. If the hole diameter is set to an appropriate size, the outflow stops when a certain amount of liquid remains inside during low tide, so it is preferable to dissolve the nutrients in the cylinder without waste. As for the input amount of the fertilizer agent, since fertilization is carried out at low tide during the day and it may not be possible to supply fertilizer every day depending on the weather, it is desirable to contain at least 5 kg so that the material does not run out. Note that the size of the holes in the upper lid does not have to be the same as the size of the holes in the lower lid, but there may be an overflow due to excessive intrusion of seawater into the fertilizer cylinder by waves during rough weather, or clogging of the holes due to excessive intrusion and reproduction of plankton. Therefore, it is preferable that they are the same size as much as possible.

[0021] As the fertilizer agent to be put inside the fertilizer cylinder, it is preferable to use one or more co-products of ammonium sulfate, steel slag, steel slag containing phosphoric acid, iron oxide, and iron filings. Also, since it is finally limited to something that becomes liquid, when supplying nutrients with solids such as steel slag as the fertilizer agent, it is preferable to set the fertilizer agent packed in a natural burlap bag or the like separately on the seabed or in the sea, as it enables composite fertilization of iron, magnesium, silicon, etc.

Example

[0022] Thirty-three items were prepared, each with a diameter of 10 cm, a height of 50 cm, and one hole of φ0.8 mm drilled in each of the upper and lower lids, and 5 kg of ammonium sulfate was placed inside the cylinder. A fertilization test was conducted at the Susabinori farm in Noguchi, Minamihama-cho, Chita-gun, Aichi Prefecture. The fertilization test was carried out for two weeks from February 22 to March 7, 2023. During the test period, ammonium sulfate was replenished once every two days at low tide during the day.

[0023] In the nori farm, under the tidal level change shown in Figure 4-1, a fertilization cylinder was installed on the nori net. As shown in Figure 5, seawater was sampled from the test area where the fertilization cylinder was installed in the nori farm and the control area that was far enough away from the test area so as not to be affected by fertilization, and the increase in the concentration of ammonia nitrogen in the seawater was investigated. The tidal level was based on the tide table for each sea area of the Japan Meteorological Agency.

[0024] As shown in Figure 4-2, the nori net is suspended from piles and is bent and hanging down. Its lower end is different at the center and the end of the nori net, and the position of the lower end of the nori net has a certain range. The fertilization cylinder for nori cultivation of the present invention is installed so that the holes at the lower part of the fertilization cylinder are generally within this range. Also, for nori, according to the agreement of stretching nori to ○○ mm from the standard tidal level determined in each region, nori farmers stretch nori to that height. Here, "○○ mm" varies depending on the region and the fishing cooperative and is determined as appropriate.

[0025] Under the arrangement in Figure 5, when confirmed by the layout diagram of the water sampling points around the fertilization cylinder, the time when the nori net and the fertilization cylinder began to be immersed in seawater is shown in Figure 6-1, and ammonia nitrogen of up to about 20 μg·L -1 was confirmed. Then, at the time of Figure 6-2 when the immersion time had passed for 3 hours, the ammonia nitrogen was up to about 370 μg·L -1 At this time, when the ebb tide occurs and it becomes Figure 6-3 where the fertilization cylinder emerges above the sea surface, a high concentration of ammonia nitrogen can be confirmed in a narrow range. This is considered to be because there is little seawater around the ammonia nitrogen that has come out of the cylinder to diffuse when the fertilization cylinder is about to rise from the sea surface.

[0026] On the other hand, at the time of Figure 6-4 when the nori net and the fertilization cylinder are exposed at low tide, the increase in ammonia nitrogen is 10 μg·L-1 It was possible to save to that extent. Furthermore, when 9 hours had elapsed since the start of fertilization and the fertilizer cylinder was immersed in seawater again as shown in Fig. 6-5, it was confirmed that ammonia nitrogen was distributed widely and could supply nutrients to the surrounding laver. From these results, it is considered that the fertilizer cylinder locally concentrates around the fertilizer cylinder at low tide and supplies ammonia nitrogen uniformly over a wide range from the fertilizer cylinder at high tide.

[0027] When comparing the cross-sectional areas from the leaf lengths and leaf widths of the laver samples in the test plot and the target plot, as shown in Fig. 7, a yield increase of about 50% was confirmed. Regarding the color tone, as shown in Fig. 8, the color faded in the target plot, but no color fading was observed in the test plot.

Explanation of Signs

[0028] 1 Fertilizer cylinder body 2 Upper lid 3 Hole in the upper lid 4 Lower lid 5 Hole in the lower lid 6 Fertilizer 10 Fertilizer cylinder 11 Nutrient 20 Laver net 21 Pile 30 Sea 31 Seabed

Claims

1. A fertilizer cylinder for use in laver cultivation, where one hole is provided at each of the upper and lower parts of the fertilizer cylinder. The inside of the fertilizer cylinder can be filled with a fertilizer that contributes to the growth of laver. When the tide level drops and the fertilizer cylinder is exposed above the sea surface, air enters through the hole at the upper part of the fertilizer cylinder, and an aqueous solution formed by dissolving the fertilizer in the seawater that has invaded the inside of the fertilizer cylinder is discharged from the hole at the lower part of the fertilizer cylinder. The size of the hole at the lower part is such that the surface tension when the aqueous solution exits from the hole at the lower part of the fertilizer cylinder is equal to the water pressure of the aqueous solution inside the fertilizer cylinder, and the size is such that the discharge of the aqueous solution from the hole at the lower part of the fertilizer cylinder stops. The aqueous solution diffuses around due to the change in tide level, and fertilization is carried out on the laver net. A fertilizer cylinder for laver cultivation is characterized by this.

2. The fertilizer cylinder for laver cultivation according to claim 1, characterized in that a transparent material is used for the lid of the fertilizer cylinder so that the usage amount of the fertilizer can be easily confirmed.

3. The fertilizer cylinder for laver cultivation according to claim 1 or 2, characterized in that a metal pipe is used for the body of the fertilizer cylinder to dissolve trace amounts of metal in the fertilizer.

4. A laver cultivation fertilization method, characterized by filling the fertilizer cylinder for laver cultivation according to claim 1 with the fertilizer, installing it at the same height as the laver net on the support on which the laver net is installed, so that the fertilizer does not elute during low tide and the aqueous solution is discharged during immersion.

5. The laver cultivation fertilization method according to claim 4, characterized in that a co-product containing one or more of ammonium sulfate generated in the steel industry, steel slag, steel slag containing phosphoric acid, iron oxide, and iron filings is used as the fertilizer.

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