JP2005126678A - Soil-improving material and method for improving soil by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for improving soil by converting alkaline soil unsuitable for planting and not exhibiting humoral property into soil having a pH suitable for growing plants, and a method for improving the soil by using the same. <P>SOLUTION: The soil-improving material is provided by proliferating and preserving aerobic bacteria including alkaliphilic microorganisms or conditional anaerobic bacteria by using woody chips having ≤25 mm length including coarse woody chips having 7-25 mm length as culturing medium, and adding an activation-accelerating material. By mixing the soil-improving material with the highly alkaline soil to aim at the improvement of water permeability and water-holding property, the pH of the highly alkaline soil is lowered by utilizing the carbonatation by CO<SB>2</SB>exhausted by the respiration of the groups of microorganisms, and also the soil is changed by planting an alkali-loving plants as pioneer plants and utilizing a soil pH-improving effect by the plants. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a soil improvement material and a soil improvement method using the same for improving a soil having no pH in a highly alkaline soil unsuitable for planting into a soil having a pH suitable for plant growth.

  In recent years, with the advancement of civil engineering technology, a large amount of highly alkaline soil including bentonite and cement has been discharged from construction sites, and since it is an industrial waste, its disposal method has become a social problem. In addition, difficulty in planting trees on highly alkaline soil exposed by the construction work, deterioration of cultivation environment in soil made highly alkaline by salt accumulation, and the like have been regarded as problems.

As countermeasures, use a mixture of sulfate materials (iron sulfate, potassium sulfate, etc.), neutralizing materials such as sulfur powder and humic acid, or use high quality soil such as masato soil or improved soil on highly alkaline soil. Soil methods have been taken, soil neutralization with organic acids created by microorganisms, and soil improvement by carbonation by CO ₂ aeration have been studied.

However, the neutralizing material is easy to run away, and there is a problem that it becomes ineffective in a short period of time, becomes highly alkaline again, and requires a large amount of neutralizing material and labor. In addition, the Soil Law also requires a large amount of high-quality soil, and new natural destruction occurs in the land where the soil for the soil for use is collected. Moreover, even if a plant is planted on the soil, there is a concern that the root may reach alkaline soil with the growth of the plant and cause a growth failure. At the same time, each method has drawbacks such as a long construction period and high costs, and a simple and inexpensive improvement method for these high alkaline earths has been desired.
JP 2003-265038 A JP 2000-136525 A JP 2000-41479 A Ryoichi Yamada, Yoshio Sudo, Toshiro Maruyama “Fundamental study on improvement of dewatered cake to soil revegetation base material due to muddy water treatment” JSCE Proceedings VII 692 21 "Effective use of construction sludge" Advanced Construction Technology Center (1998)

Therefore, the present invention uses, as a culture substrate, wood chips made from plant materials such as pruned branches and cut grass of green trees that are general wastes, and is a naturally occurring filamentous fungus, bacteria, By culturing a large number of microorganisms including aerobic and conditional anaerobic bacteria such as actinomycetes, and increasing the activity of these microorganisms by mixing with highly alkaline soil, CO ₂ generated by respiration of microorganisms It makes it a subject to reduce soil pH by the power of carbonation.

In order to solve the above problems, the first invention were selected microorganisms rich in alkalophilic microorganisms naturally occurring, the pH of utilizing carbonated by CO ₂ that these microorganisms can cause highly alkaline soils It is invention of the soil improvement material characterized by reducing and changing to the soil suitable for planting.

The second invention uses pruned branches, cut grass, etc. of greening trees, which are general wastes, as raw materials, and wood quality of 25 mm or less containing 10 to 40%, preferably 20 to 30%, of woody coarse chips of 7 to 25 mm in length. Chips are mixed into highly alkaline soils to improve the physical and breathability of the soil. If the woody coarse chip content is 10% or less, the water permeability is not improved, and if it is 40% or more, the activity of microorganisms is inferior. The action of the woody large chip can increase the supply of air into the soil without taking special measures such as air supply and aeration, and can activate the microorganism group. The CO ₂ that activated microorganisms occurs lowering the soil pH, construction sludge that does not exhibit a humoral, a highly alkaline soils and construction waste soil, pH 8.6 following planting soil is drained standards specified by the Ordinance of the Ministry of the Environment It is the invention of the soil improvement material characterized by improving to.

Further, the third invention is a method of culturing a group of microorganisms containing alkalophilic filamentous fungi, bacteria, actinomycetes, etc. using a culture substrate comprising a wood chip and activating it to generate CO ₂ in large quantities and over 2 months. The soil improvement material is mixed with the soil to improve the soil pH.

In the fourth invention, immediately before mixing the soil improvement material with the soil, the CO ₂ concentration generated by the microorganism group is increased to 1 to 15%, preferably 5 to 10%, and the generation of CO ₂ is continued for 2 months or more. It is an invention of a soil improvement method by using an activation promoting material mainly composed of an easily decomposable organic substance capable of maximizing the carbonation ability.

The fifth invention of the soil improving agent, and mixed in a high alkaline soil showing no liquid, in activated soil improvement method for reducing the pH of the highly alkaline soils by carbonation of CO ₂ microorganisms occurs with soil It is an invention of a soil improvement method characterized by no special operations such as aeration and soil agitation after mixing.

  According to the present invention, it is possible to easily improve construction sludge, which is industrial waste, or highly alkaline soil that requires soil improvement, using pruned branches, cut grass, and the like that are regarded as general waste. As a result, for example, even construction sludge treated as a nuisance as industrial waste can be used as planting soil, and since the pH value is 8.6 or less, conventional construction sludge and construction sludge improved soil The wastewater treatment facility that was necessary for the construction work using the slab is no longer necessary.

  Embodiment of this invention is mixing the soil improvement material containing the activated alkaliphilic microorganisms to a highly alkaline soil, and when microorganisms are not activated, pH value is set to 8. It is difficult to lower it to about 6.

The basic principle of the present invention is the application of carbonation in which CO ₂ gas dissolves in water and reacts with Ca (OH) ₂ to form calcium carbonate and lower the pH.

The CO ₂ concentration is usually about 0.03% in the atmosphere. Compost compost is about 0.1% to 0.5%. However, in the soil improvement material according to the present invention, although it is the maximum value, surprisingly, a high concentration of CO ₂ continues to be released over 150 to 300 times the normal atmosphere over a long period of two months or more. If this condition is not met, it is difficult to achieve the original objective.

  As a culture substrate for the microorganism group in the present invention, a wood chip having a length of 25 mm or less containing a wood coarse chip having a length of 7 to 25 mm in a volume ratio of 10 to 40%, preferably 20 to 30% is used. This is effective for improving soil physical properties such as air permeability, water permeability and water retention. These improvements in the physical properties of the soil supply necessary air to the microorganism group constituting the soil improvement material according to the present invention, hold the necessary moisture, and lead to the activation of the microorganism group. Therefore, the culture substrate must contain coarse chips of the above length.

  Wood chips containing pruned branches usually have a C / N ratio of 100 or more, and this figure means that fermentation cannot be completed easily. In other words, it means that the growth of microorganisms is sustained over a long period of time, and sudden nitrogen starvation which is a problem in bark compost or the like is relatively difficult to occur.

  In addition, the microorganism group cultured on the wood chip is always affected by the environment and its activity changes. In the cultivation process using wood chips, initially, aerobic microorganisms (absolute aerobic bacteria, etc.) are activated by obtaining a large amount of oxygen and organic matter, but eventually, conditional anaerobic bacteria become mainstream. A soil improvement material is prepared by adjusting the activities of the aerobic microorganism group and the conditional anaerobic bacteria group for a long period of time.

  At the very beginning of the cultivation, harmful pathogens and pests contained in the raw materials of the soil amendment materials survive, and are susceptible to anaerobic fermentation due to lack of oxygen. As a result, phenolic acids harmful to plants are generated and remain. Often has a negative effect on plant growth. In order to avoid this, it is necessary to proceed aerobically while paying attention to aeration and water flow. In the meantime, the fermentation temperature of 60 to 70 ° C. must be maintained for about one week to kill harmful pathogens and pests.

  After that, the fermentation process centered on the aerobic aerobic microorganism group and the aerobic conditional anaerobic bacteria group was added. By mixing with alkaline soil, the pH of highly alkaline soil can be lowered.

  The mixing ratio of the soil improving material according to the present invention to the soil is 20% to 50% of the soil in volume ratio. This ratio should be varied according to the pH value of the soil in need of improvement. For example, 20% is sufficient for construction sludge having a pH of about 9, but 30% or more is appropriate for a pH of about 12.

  Wood chips originally have a large number of microorganisms growing themselves, and the constituent species and activity of the microorganism group are constantly changing. In the present invention, since the soil improvement material is mixed directly into the highly alkaline soil, the applied microorganism group must be able to be sufficiently activated in a highly alkaline environment.

  Therefore, a group of microorganisms with high activity in high alkaline soil was selected from a large number of trial improvement materials. This microorganism group is subcultured as an inoculum and inoculated and used as the soil improvement material of the present invention.

  However, since it is impractical to cultivate the inoculum, it has been found that there is a method in which the inoculum is always in a dormant state and activated when necessary. As a result of investigating the relationship between the activity of microorganisms and moisture, the water content (weight ratio to the field water content) was 30% or less, and it was possible to make it almost dormant by storing it in a way that avoids water permeability due to rainfall. .

  Here, the water content is a ratio with respect to the field water capacity measured using a moisture meter to which a new calibration curve for soil improvement materials was input using a sample screened off with a 2 mm sieve.

  In soil improvement by this method, it takes some time to lower PH to 8.5 or less. As a countermeasure, it is possible to shorten the period by cultivating an alkali-resistant plant (pioneer plant) such as Sesbania and promoting neutralization of soil.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

  When soil improvement materials composed of wood chips with different activities were mixed with high alkaline soil at a volume ratio of 30%, the soil improvement material having an activity of 1.6 was initially pH 11.1. The fact was found that the highly alkaline soil was lowered to pH 8.6. This is a technology that could not be achieved with existing technology. The pH change at this time is shown in FIG. 1 and FIG. In the figure, (1) is a comparative example of construction sludge itself, and (2) is an example of adding 30% soil improvement material to construction sludge in the example. 8 or 10 days after mixed use (1) The pH in the comparative example was maintained at 10.0 or higher in the soil and 9.5 or higher in the leachate, but (2) in the examples, the pH was 8.5 and 8.4, respectively. It was.

Here, 3.7 liters of soil improvement material was put into a special glass container (8 liters), and the CO ₂ concentration after 150 minutes was measured with a gas detector tube, and the activity was judged by this measured value (%). The soil pH was determined by adding 50 g of distilled water to 10 g of the sample, stirring, and allowing to stand for 1 hour, and then measuring with a pH meter with an automatic temperature compensator. The leachate pH was determined by adding distilled water to 10 liters of soil in a 45-type planter. One liter was irrigated and the pH of the water leached to the bottom of the planter was measured.

When soil-improvement materials containing dormant microorganisms were added to the soil-improving material, vegetable oil residue, refined sugar beet, soymilk pomace, mushroom medium, dried chicken manure, ammonium sulfate, and urea were added to the soil-improving material. The amount of CO ₂ generated by the soil improvement material added by 1% reached 5.6%. In the section where the addition amount was increased to 4%, more ammonia gas was generated than CO ₂ . Therefore, it was considered that the addition amount of the activation promoting material was 1 to 2%.

Urea has a high nitrogen concentration and a rapid generation of ammonia gas was observed, but the amount of CO ₂ generated was small and did not satisfy the conditions required for the present invention. Depending on the activation-promoting material, the amount of CO ₂ generated immediately after addition is satisfactory, but the sustainability is inferior, and the initial CO ₂ generation amount is not large, but it is generated over a long period of time. It is recommended to select an activation promoting material including protein, protein and carbohydrate. The results are shown in Table 1.

* N weight g in additive activation promotion material / 1kg soil improvement material
Table 1 CO ₂ emissions due to the addition of activation promoting materials

The soil improvement material was preserved and tested while avoiding the infiltration of rainwater. As a result of examining the activity of the microorganism by CO ₂ concentration while changing the amount of water added, it was found that if the water content was 30% or less, the microorganism was almost dormant for 6 months or more. This means that it can be used as an inoculum group by hydrating and activating a sample stored at a water content of 30% or less. The results are shown in FIG.

We examined soil improvement methods at actual sites using soil improvement materials during storage. First, in order to activate a dormant microorganism group as a soil improvement material, the dormancy was broken by the following method. That is, the moisture content of the soil improvement material was adjusted to 70%, and the activation promoting material was added by 2% by weight. As a result, the CO ₂ concentration at the time of storage of 0.3% was activated to 5.2% at the time of test.

  This soil improvement material is mixed with high alkaline construction sludge of pH 12.0 + construction residual soil at a volume ratio of 30%, and planted or seeded with ginseng grass, turf (tall fescue), green manure crop (sesbania), and then the soil, leaching Changes in water pH and crop growth were investigated, and the results are shown in FIGS. In the figure, 1 (construction sludge) and 2 (construction sludge + construction residual soil) are comparative examples, 3 (construction sludge + construction residual soil + soil improvement material) and 4 (construction sludge + construction residual soil + soil improvement material + granular foundation) ) Is an example. The survey was conducted from May 20, 2003 to August 30, 2003. The change in pH of the soil after the treatment is shown in FIG. The soil pH was measured with a pH meter equipped with an automatic temperature compensation device after adding 50 g of distilled water to 10 g of a sample obtained by collecting and mixing soil having a depth of 5 cm from five locations in each test section, and stirring for 1 hour after stirring. . As a result, the soil pH decreased immediately after the test, and decreased to pH 8.6 that satisfied the discharge standard after about two months of the test.

  FIG. 5 shows the transition of the leachate pH. For the leachate, 5 to 10 cm depth of soil was collected from 5 locations in each test zone, and the mixed sample was packed in a φ125 mm PVC pipe to a height of 20 cm, 1000 cc of distilled water was added from the top, and leaching from the bottom. The pH of the water was measured. As a result, the pH dropped to 8.5 or less after 2 months of the test.

  FIG. 6 shows the cumulative value of the cut grass weight of the turf (tall fescue). Although it was a result of about 2 months, it became clear that the weight of the cut grass of the example which improved the soil exceeded the comparative example.

  The soil after mixing with soil improvement materials and after a lapse of 1 to 2 months may have a pH that is slightly too high as a planting soil at around pH 8.6. Then, the confirmation test of the plant species which can be grown in such a soil was implemented. As a result, immediately after soil improvement, alkali-tolerant plants such as tall fescue, perennial ryegrass, bermudagrass, and kobashishiba grew well on the lawn, and sesbania, crotalaria, solgo, oat, alfalfa, etc. achieved good results for green manure plants.

  The growth situation of Sesbania, one of the green manure plants, is shown in FIG. Sesbania was sowed on May 27, 2003, and mowing was conducted on September 1, 2003. Although it is a survey three months after the start of the test (September 3, 2003), the soil pH of the tall fescue planting zone in the construction sludge was 11.0, but in the Sesbania district it is 9.9 to 8.5. From this, it was found that Sesbania itself has an effect of improving soil pH. Therefore, it is preferable to select a plant having a soil pH improving effect, such as sesbania, as a soil improving plant, and to make use of the improving effect of these crops.

At the same time, the occurrence of CO _{2 in} the soil was examined. The results are shown in FIG. 8, and a high CO ₂ concentration was confirmed in the soil-improving material mixed section even though 9 months had passed after mixing. In the comparative construction sludge zone and construction sludge + residual soil zone, almost no CO ₂ was detected.
[Other Embodiments]

  In the examples, the crushed pruned branches were used as the raw material for the wood chips. However, in other embodiments, construction waste, coconut seed coats, etc. may be used. In addition, plant material or livestock manure can be used as a supplement for moisture and nitrogen during fermentation.

  As an activation promoting material, vegetable oil extraction residue has obtained the best results, but other low molecular sugars, proteins, amino acids and other readily decomposable organic substances can be used by adjusting the concentration used.

  The microorganism group according to the present invention includes an aerobic microorganism group, and any type of aerobic microorganism group or a conditional anaerobic bacteria group may be used. However, there are cases where the number of alkalophilic microorganisms is small in the natural state, and in order to promote fermentation, better results can be obtained by adding a part of the preserved microorganisms as a seed fungus to the woody culture substrate.

  In the present invention, Sesbania has been shown as a plant that supplementarily improves the pH of highly alkaline soil, but any type of plant can be used as long as it is an alkali-tolerant plant that has a function of lowering soil pH by cultivation.

  The disposal of construction sludge is a major social problem in terms of its method, location, and cost, and it causes illegal dumping because it is difficult to properly treat. Therefore, reusing these construction sludge as planting soil is a problem for today's construction industry, and the present invention can be utilized as a solution.

Tree pruned branches are treated as general waste, and the current situation is that they also spend a great deal of money on incineration. Therefore, when the tree pruned branch is used as one of the woody culture base materials for the soil improvement material, it is useful as a waste recycling.

Change of soil pH of improved soil by soil improving material according to the present invention PH change in leachate of improved soil by soil improvement material according to the present invention Water content and carbon dioxide generation amount of soil improvement materials Demonstration test of soil improvement material according to the present invention (result of soil pH improvement) Demonstration test of soil improvement material according to the present invention (leachate pH improvement result) Demonstration test of soil improvement material according to the present invention (tall fescue grass lawn weight) Demonstration test of soil improvement material according to the present invention (Sesbania fresh grass weight) Demonstration test of soil improvement material according to the present invention (CO ₂ generation amount after 9 months)

Claims (6)

A soil improvement material containing microorganisms such as filamentous fungi, bacteria, and actinomycetes, which are alkalophilic microorganisms cultivated on coarse wood chips and wood culture substrates, improving the air permeability, water permeability and water retention of highly alkaline soils A soil improvement material characterized by lowering the soil pH and changing to soil suitable for planting. The soil improvement material includes a woody coarse chip having a length of 7 to 25 mm. The coarse chip improves the air permeability and water permeability of the soil, and the activity of the microorganism group as a woody culture substrate is maintained for a long period of time. The soil improvement material according to claim 1, wherein the following wood chip serves as a wood culture substrate that promotes the initial activity of the microorganism group. 3. The soil improvement material according to claim 1, wherein the ratio of the wood coarse chip to the wood chip is 10 to 40%, preferably 20 to 30% of the wood coarse chip in a volume ratio. The soil improvement material according to any one of claims 1 to 3, wherein the microorganism group includes a microorganism group that continuously generates a high concentration of CO ₂ for two months or more. The soil improvement material according to any one of claims 1 to 4, wherein an activation promoting material capable of generating a high concentration of CO ₂ is mixed in order to maximize the carbonation ability of the microorganism group. . The soil improvement method characterized by improving to the soil suitable for planting by mixing the soil improvement material of Claim 1 thru | or 5 with highly alkaline soil.