JP2018007646A - Nutrient circulation system, soil conditioner, and nutrient circulation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide nutrient circulation systems capable of efficiently utilizing nutrients.SOLUTION: A nutrient circulation system 1 has a field 10, an underdrain 20 laid under the field 10, a water source 30 for storing drainage from the underdrain 20, a water supply device 40 for pumping up the drainage from the water source 30, a microbubble generator 42 for generating microbubbles in the drainage pumped up by the water supply device 40, the water supply device 40 returning the drainage containing the microbubbles generated by the microbubble generator 42, to the field 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nutrient circulation system, a soil improvement material, and a nutrient circulation method.

  For example, Patent Document 1 predicts a fertilizer amount to be administered to the field by using detection means for detecting the fertilizer concentration of groundwater in the field, a detection value of the detection means, and a fertilizer amount administered to the field. There is disclosed a farm environment purification system comprising a computing means for computing.

  In addition, Patent Document 2 discloses a simple method of forced water flow and forced drainage of soil, a method of agricultural labor-saving rhizosphere soil environment control, forced water flow and microbubble supply to the rhizosphere soil, An integrated soil environment control apparatus that performs many tasks in one system, which combines a wet rhizosphere drainage and soil pest control method and apparatus, is disclosed.

JP 2005-235074 A JP2012-120523

  The purpose is to provide a nutrient circulation system that can efficiently use nutrients.

  The nutrient circulation system according to the present invention includes a field, a culvert embedded in the field, a water source that stores drainage from the culvert, a water supply device that pumps wastewater from the water source, and drainage that is pumped by the water supply device A microbubble generator for generating microbubbles therein, and the water supply device returns waste water containing the microbubbles generated by the microbubble generator to the field.

  Preferably, the water source further includes a porous structure to which microorganisms are fixed.

  Preferably, the underdrain includes a drain pipe that drains to the water source, and a hydrophobic material layer that is located above the drain pipe and contains an insolubilizing material that insolubilizes bamboo and heavy metals.

  Preferably, the field includes a soil layer containing bamboo as compost.

  Preferably, the field includes a soil layer containing bamboo as a compost to which a fermentation accelerator is added.

  Suitably, the said field contains the soil layer containing the insolubilization material which insolubilizes a heavy metal.

  The soil improvement material which concerns on this invention mixed the bamboo material to which the fermentation promoter was added, and the insolubilization material which insolubilizes a heavy metal.

  The nutrient circulation method according to the present invention includes a step of storing wastewater from a field in a water source, a step of generating fine bubbles in the wastewater stored in the water source, and a step of returning wastewater containing fine bubbles to the field.

  A nutrient circulation system that can efficiently use nutrients can be provided.

It is a figure which represents nutrient circulation system 1 typically. It is a figure showing the experimental result of a heavy metal insolubilization process.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically showing a nutrient circulation system 1.
As illustrated in FIG. 1, the nutrient circulation system 1 includes a field 10, a culvert 20, a water source 30, a pump 40, and a microbubble generator 42.
The field 10 is a field or a farm for cultivating crops. The farm 10 has a soil layer 12 and a subsoil layer 18. Here, the soil formation layer refers to a soil layer in a range dug up when cultivating crops. The subsoil layer refers to a soil layer in which plant roots are infested or a soil layer below the topsoil. A plurality of underdrains 20 are embedded in the farm 10 in parallel. The underdrain 20 includes a long groove 22, a drain pipe 24, and a hydrophobic material 26. The underdrain 20 may have an auxiliary underdrain.

The long groove 22 is a groove formed by excavating the agricultural field 10 with a trencher or the like.
The drain pipe 24 is laid at the bottom of the long groove 22. For example, the drain pipe 24 is formed by connecting a synthetic resin pipe such as vinyl chloride, an unglazed earth pipe, or a bamboo pipe. In addition, a hole is provided in the upper wall surface of the drainage pipe 24 laid.
In this example, the drain pipe 24 is formed by connecting split bamboo or bamboo pipe. A bamboo pipe is a bamboo with a knot removed, penetrated inside, and provided with a hole in the upper wall surface. The water that has passed through the inside of the split bamboo or the bamboo pipe is imparted with characteristics useful for improving the field drainage environment, as the active ingredient similar to the bamboo chip described later exudes from the bamboo pipe.

The hydrophobic material 26 is filled in the long grooves 22 while leaving the depth of the soil layer 12 to form the hydrophobic material layer 16. The hydrophobic material layer 16 formed by the hydrophobic material 26 is covered with the soil layer 12.
For example, the hydrophobic material 26 is bamboo material. In this example, the hydrophobic material 26 is a bamboo chip formed by finely cutting raw bamboo. The size of the bamboo chip may be changed as appropriate according to the amount of drainage, but the maximum diameter (maximum diameter) is preferably 5 mm or more and 40 mm or less.

In this example, the hydrophobic material 26 may include an insolubilizing material that insolubilizes heavy metals. For example, the insolubilizing material that insolubilizes heavy metals is a fossil mineral. The fossil mineral contains lime. In this example, the fossil mineral is a natural fossil mineral. Note that the natural fossil mineral may include iron sulfate. Natural fossil minerals insolubilize lead, copper, chromium (III) and the like. In addition, natural fossil minerals containing iron sulfate insolubilize arsenic.
Thereby, in the hydrophobic material layer, the heavy metal eluted from the soil is insolubilized and becomes a hydroxide. For this reason, heavy metal can be prevented from flowing out to the water source 30 through the underdrain. Moreover, since fossil minerals are inexpensive, insoluble in harmful heavy metals can be realized at low cost.

The water source 30 is a water supply source used as irrigation water. Moreover, the water source 30 is a drainage destination of water. For example, the water source 30 is a natural or artificial lake, swamp, lagoon, pond, or river. In this example, the water source 30 is a lagoon.
The water source 30 stores drainage from the underdrain 10. For example, the water source 30 stores the waste water from the farm 10 through the drain pipe 24 of the underdrain 20.
The water source 30 includes a porous structure in which microorganisms are fixed in water. For example, the porous structure is diatomaceous earth 32. For example, the diatomaceous earth 32 is installed on the wall surface of the water source 30. In this example, the diatomaceous earth 32 is submerged in water. Since the diatomaceous earth 32 is porous, microorganisms that purify the water quality tend to settle on the diatomaceous earth 32.

  The pump 40 is an example of a water supply apparatus according to the present invention. For example, one or more pumps 40 return the wastewater stored in the water source 30 to the farm 10. Further, for example, the pump 40 pumps up the drainage from the water source 30 and returns the pumped-up drainage to the farm field 10. In this example, the pump 40 pumps up the wastewater stored in the water source 30 and returns it to the farm field 10 through the water supply pipe 46.

The microbubble generator 42 is an example of a microbubble generator according to the present invention. The microbubble generator 42 generates microbubbles. Here, the microbubble means a bubble having a diameter of 1 μm to 100 μm at the time of generation. The diameter of the microbubbles gradually decreases in water, and then the microbubbles are completely dissolved. For example, the microbubble generator 42 dissolves the generated microbubbles in the waste water pumped up by the pump 40. The pump 40 returns the wastewater in which the macro bubbles are dissolved to the field 10. In addition, the fine bubble generator may generate ultra fine bubbles or nano bubbles having a diameter of 1 μm or less.
For example, the microbubble generator 42 generates microbubbles in the wastewater stored in the water source 10. In this example, the microbubble generator 42 generates microbubbles containing nitrogen, oxygen, carbon dioxide, etc. in the atmosphere in the waste water pumped up by the pump 40. The pump 40 returns the wastewater containing the microbubbles generated by the microbubble generator 42 to the field 10.

Dissolving microbubbles in the wastewater increases the oxygen concentration in the wastewater, activates microorganisms, and promotes water purification. Furthermore, when the water source 30 is eutrophied, the activated microorganisms promote the decomposition of nitrogen components that cause eutrophication. By returning the wastewater containing the decomposed nitrogen component to the field 10, the crop can easily absorb the nitrogen component. For this reason, the usage-amount of a fertilizer can be suppressed and the crop yield can be increased. In addition, microbubbles containing nitrogen, oxygen, carbon dioxide and the like in the atmosphere are mixed to generate nitric oxide. This can be expected to promote the growth of crop roots. Furthermore, by promoting the growth of the roots of the crop, the crop can efficiently absorb nutrients. Moreover, the dirt inside the water supply pipe 46 is removed by the micro bubbles, the water supply pipe 46 becomes difficult to age, and the service life of the water supply pipe 46 increases.
In addition, in this embodiment, although the form which the pump 40 and the microbubble generator 42 cooperate was demonstrated as a specific example, the pump 40 may have a function to generate a microbubble.

Next, the soil formation layer will be described.
The soil layer 12 contains bamboo as compost. For example, the soil layer 12 contains bamboo powder as compost. In addition, the soil layer 12 contains bamboo powder to which a fermentation accelerator is added as compost. For example, the soil formation layer 12 contains bamboo powder to which stevia is added as a fermentation accelerator as compost. Moreover, the earthen layer 12 may contain the heavy metal insolubilizing material mentioned above. Moreover, the soil preparation layer 12 may contain microorganisms. For example, the microorganisms are lactic acid bacteria, natto bacteria, and yeasts. In this example, the soil layer 12 contains bamboo powder to which stevia is added, a heavy metal insolubilizing material, and a soil improving material containing microorganisms.

An active ingredient to be described later oozes out from the bamboo powder contained in the soil layer 12. Thereby, the advantage of using bamboo powder is great, such as the promotion of soil agglomeration. On the other hand, bamboo powder had a high C / N ratio, and when the decay was insufficient, the risk of nitrogen starvation was high. Here, the C / N ratio refers to the ratio of carbon to nitrogen. When the C / N ratio is high, nitrogen starvation occurs and growth failure occurs. Furthermore, bamboo powder has a long period of time, about 3 to 4 months, until it is fully composted.
Therefore, stevia is used as a microbial fermentation promoter. Thereby, fermentation of bamboo can be promoted, C / N ratio can be reduced, and nitrogen starvation can be prevented. Furthermore, by using stevia, the early ripening of bamboo can be realized.
In addition, by using chemical fertilizers when cultivating crops, nitrate nitrogen is washed away into groundwater and rivers, causing environmental pollution problems. Furthermore, by using a chemical fertilizer for the soil layer 12, nitrate nitrogen accumulates in the crop. This is a cause of a decrease in taste such as bitterness of crops.
Therefore, stevia is included in the soil formation layer 12. Stevia retains nitrate-reducing thermophilic bacteria that can suppress nitrate nitrogen loss and nitrate nitrogen accumulation in crops.

Moreover, there is a risk that bamboo materials contain heavy metals due to the vegetation environment of bamboo materials. Furthermore, in a fermentation process, there exists a risk that pH will fall and a heavy metal will elute because bamboo material carries out lactic acid fermentation. There is also a risk that heavy metals may be eluted due to a drop in pH due to acid rain and a drop in pH due to the type of compost used. Therefore, elution of heavy metals into the soil is prevented by using a heavy metal insolubilizing material.
Conventionally, the removal of toxic heavy metals has been centered on a cleaning process or moving removal using a large apparatus, and there has been a problem in cost and workability. However, in the present application, natural fossil minerals used as heavy metal insolubilizing agents are inexpensive, and therefore can reduce the environmental risk due to vegetation of bamboo. Moreover, heavy metals can be removed by on-site processing without using large equipment. Moreover, heavy metals can be insolubilized safely by using fossil minerals.

Next, the effect of the bamboo chip used as the hydrophobic material 26 will be described. In addition, the bamboo powder used for the clay layer 12 has the same effect.
In this example, by using bamboo chips as the hydrophobic material 26, the water drained through the hydrophobic material 26 is imparted with characteristics useful for improving the field environment due to the active ingredients that have exuded from the bamboo chips.
More specifically, the water drained through the hydrophobic material 26 becomes weakly alkaline due to the alkaline component exuded from the bamboo chips, and iron dissolved in the water drained from the soil of the field 10 is oxidized. To prevent. As a result, the amount of iron oxide contained in the water drained from the drain pipe 24 is reduced, and there is no adverse effect on the surrounding environment such as the death of small animals due to iron oxide.
In addition, the water supplied through the hydrophobic material 26 generates ethylene gas in the process of oxidative decomposition of the methionine component exuded from the bamboo chip, thereby obtaining a bactericidal effect and an insect repellent effect. Moreover, since methionine is a transporter of selenium and selenium, which is an antioxidant mineral, it can also be expected to have an antioxidant effect.
In addition, the water supplied through the hydrophobic material 26 is imparted with antioxidant, antibacterial, and deodorizing effects by the growth of useful microorganisms such as lactic acid bacteria and yeast by the amino acid component exuded from the bamboo chip. Can prevent crop pests.
In addition, the water supplied through the hydrophobic material 26 is a useful microorganism that contributes to crop growth, improvement of soil environment, and drainage purification by amino acids (glycine, glutamic acid, aspartic acid, etc.) exuded from bamboo chips. It is given the property of proliferating and the field environment is improved by the action of this useful microorganism. Furthermore, since the bamboo structure is porous, useful microorganisms tend to settle on the bamboo chips.

As a result, the underdrain 20 gives the characteristics of the active ingredient contained in the bamboo to the water drained through the hydrophobic material 26 (the hydrophobic material 26 and the drainage pipe 24 when the bamboo pipe is used as the drainage pipe 24). The environment of the water source 30 and the farm 10 can be improved.
Bamboo chips are superior in corrosion resistance in the soil compared to conventional straw and wood chips. As a result, the time interval for replacing the hydrophobic material 26 is 5 to 10 years in the case of straw, about 10 to 30 years in the case of wood chips, and about 30 years in the case of bamboo chips. That's it.
In recent years, forest damage due to the expansion of bamboo forests has become a problem, and many bamboo trees have been cut down. The underdrain 20 is expected to be able to effectively use the harvested bamboo.

As described above, the nutrient circulation system 1 can return the nutrients supplied to the field 10 to the field 10 again through the underdrain 20 and the water source 30. At this time, microbubbles are contained in the drainage returned to the field 10 by the microbubble generator 42. Thereby, since the oxygen concentration in waste water increases and microorganisms are activated, the crop can efficiently absorb nutrients contained in the waste water.
Moreover, by using a soil improvement material for the soil formation layer 12, microorganisms in the soil are activated, the resistance of the soil itself is increased, the earth strength can be maintained, and further, elution of heavy metals can be prevented. Thereby, aggregation of soil can be promoted. Moreover, it is possible to prevent a decrease in geopower due to dependence on chemical fertilizers and continuous cropping failures. That is, the soil itself is always kept healthy, so that a buffering function works against any environmental change and load. Thereby, a highly productive farming environment can be provided.
The nutrient circulation system 1 uses bamboo for the farm 10 and the underdrain 20. For this reason, the essential amino acid component of bamboo is provided to microorganisms and crops. In addition, the porous structure of bamboo provides a living space for microorganisms. Furthermore, plant growth can be promoted by the high silicic acid contained in the bamboo.
Therefore, maintenance and recovery of the geopower of the field 10 and water purification of the water source 30 can be realized by circulation of the field 10, the underdrain 20, and the water source 30, and furthermore, a high-quality crop can be cultivated.

(Test results)
FIG. 2 shows the test results of the heavy metal insolubilization treatment.
FIG. 2 (A) represents the test result of heavy metal contaminated soil treatment.
In the test according to FIG. 2 (A), after a certain amount of natural fossil minerals are confused with heavy metal-eluting soil, the amount of heavy metal eluted is measured. The dissolution test was in accordance with the JIS standard soil dissolution test, and the concentration measurement of heavy metals was performed by graphite atomic absorption spectrophotometry. As a result of the test, the amount of lead elution was 0.003 mg / L as a result of mixing 30 g of natural fossil minerals per kg of soil with 8.26 mg / L of lead elution soil. Moreover, it was confirmed by a test that lead is not eluted from soil due to acid rain having a pH of about 4 to 5. Further, after insolubilization treatment, the elution test was repeated 5 times, and as a result, it was confirmed that there was no elution of lead. As a result, it was confirmed that the soil was stable for a long time without lead elution. In addition, it was confirmed that insolubilization treatment was possible even in copper and chromium (III) -eluting soil. In addition, arsenic insolubilization treatment could not be performed with natural fossil minerals alone, but iron sulfate was added to natural fossil minerals and an elution test was conducted.

FIG. 2 (B) shows the test results of heavy metal contaminated water treatment.
In the test according to FIG. 2 (B), a predetermined natural fossil mineral is added to a heavy metal contaminated aqueous solution having a predetermined concentration, and after stirring for about 1 hour, the heavy metal concentration in the filtrate is measured. In the test, natural fossil minerals (10 g / L) are added to heavy metal contaminated water, and the mixture is sufficiently stirred to separate insoluble components, and the removal rate is measured. Lead could be removed up to about 500 mg / L against natural fossil minerals (10 g / L). Moreover, removal of copper, chromium (III), cadmium and zinc was also possible. Furthermore, arsenic can also be removed by adding iron sulfate to natural fossil minerals in the same manner as heavy metal contaminated soil treatment. Further, in this method, the pH of the treated water is around 8, and the subsequent treatment such as neutralization is almost unnecessary.

DESCRIPTION OF SYMBOLS 1 ... Nutrient circulation system 10 ... Farm 20 ... Underdrain 30 ... Water source 40 ... Pump 42 ... Micro bubble generator

Claims (8)

The field,
Underdrains embedded in the field;
A water source for storing drainage from the underdrain;
A water supply device for pumping waste water from the water source;
A fine bubble generator for generating fine bubbles in the waste water pumped up by the water supply device,
The nutrient water circulation system in which the water supply device returns waste water containing fine bubbles generated by the fine bubble generator to the field. The nutrient circulation system according to claim 1, further comprising: a porous structure in which microorganisms settle in the water source. The culvert is
A drain pipe for draining to the water source;
The nutrient circulation system according to claim 2, further comprising: a hydrophobic material layer that is located above the drain pipe and contains an insolubilizing material that insolubilizes bamboo and heavy metals. The nutrient circulation system according to claim 3, wherein the field includes a soil layer containing bamboo as compost. The nutrient circulation system according to claim 4, wherein the field includes a soil layer containing bamboo as a compost to which a fermentation accelerator is added. The nutrient circulation system according to claim 5, wherein the farm includes a soil layer containing an insolubilizing material that insolubilizes heavy metals. Bamboo with added fermentation promoter,
A soil improvement material mixed with an insolubilizing material that insolubilizes heavy metals. A step of storing drainage from the farm in a water source, a step of generating fine bubbles in the drainage stored in the water source,
Returning the wastewater containing fine bubbles to the field.

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