JP3711522B2 - Soil improvement material and soil improvement method using it. - Google Patents

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, were selected microorganisms rich in alkalophilic microorganisms present in natural, utilizing carbonated by CO ₂ that these microorganisms can cause to lower the pH of the highly alkaline soils, Invented a soil improvement material characterized by changing to soil suitable for planting .

General and waste raw materials pruning branches and cutting grass and the like of the trees and plants is, 10-40% including a length of 25mm or less of the wood chips and wood coarse chips in length 7～25Mm, mixed in highly alkaline soils Improves air permeability and water permeability, which are the physical properties 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. Plant soil with a pH of 8.6 or lower, which is a drainage standard established by the Ordinance of the Ministry of the Environment, for reducing the pH of soil by CO ₂ generated by activated microorganisms and reducing highly alkaline soils such as construction sludge and construction residual soil that do not exhibit liquidity It is the invention of the soil improvement material characterized by improving to.

In addition , a soil-improving material obtained by culturing a group of microorganisms containing alkaliphilic filamentous fungi, bacteria, actinomycetes, etc. using a culture substrate made of wood chips, and activated so that CO ₂ is generated in large quantities and over 2 months. Is mixed with soil to improve soil pH.

The soil improving material just prior to mixing the soil, the CO ₂ concentration of from 1 to 15 percent microorganisms occurs, preferably is increased to 5-10%, yet the generation of CO ₂ lasted more than 2 months, carbonate 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 ability to make the liquefied.

Aeration pre Symbol soil conditioners, and mixed in a high alkaline soil showing no liquid, the carbonation of CO ₂ activated microorganisms occurs in soil improvement method for reducing the pH of the highly alkaline soils, the soil after mixing It is an invention of a soil improvement method characterized in that no special operation such as agitation of soil or soil is involved.

  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 and for 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 rapid nitrogen starvation that is a problem in bark compost or the like is relatively unlikely.

  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 culture, harmful pathogens and pests contained in the raw material of the soil amendment materials survive and are susceptible to anaerobic fermentation due to lack of oxygen. 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 newly found 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 residue, refined sugar beet, soymilk extract, 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. When the activity of the microorganism was examined by CO ₂ concentration while changing the amount of water added, it was found that the microorganism was almost dormant for 6 months or more when the water content was 30% or less. This means that it can be added to a sample stored at a water content of 30% or less, activated and used as an inoculum group. 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. 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 1 to 2 months has a pH of around 8.6, and the pH may be slightly too high for planting soil. 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, but in other embodiments, construction waste materials, coconut seed coats, and the like may be used. In addition, plant material or livestock manure can be used to supplement moisture, nitrogen, etc. 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 can be used as long as it is an aerobic microorganism group or a conditional anaerobic bacteria group. 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 (2)

A wood chip 7mm or less in length that promotes the initial activity of the microbial community, as well as improving the soil's air permeability, water permeability and water retention, as well as being necessary for the microbial community to continue to generate high concentrations of CO ₂ for more than two months. It consists of woody coarse chips of 7 to 25 mm in length, and the coarse chips are active even at pH 9 or higher and continue to generate high-concentration CO ₂ for more than 2 months on a woody culture substrate with a volume ratio of 10 to 40%. A soil-improving material cultivated by using microorganisms such as filamentous fungi, bacteria, and actinomycetes, which are alkalophilic microorganisms, as seeds, improving the air permeability, water permeability and water retention of highly alkaline soils, lowering soil pH, and planting A soil improvement material characterized by changing to soil suitable for planting. A wood chip of 7mm or less in length that promotes the initial activity of the microbial community, as well as improving the soil's air permeability, water permeability and water retention, as well as being necessary for the microbial community to continue to generate high concentrations of CO ₂ for more than two months. It consists of woody coarse chips of 7 to 25 mm in length, and the coarse chips are active even at pH 9 or higher and continue to generate high concentration CO ₂ for more than 2 months on a woody culture substrate with a volume ratio of 10 to 40%. A soil improvement method using a soil improvement material cultivated using a group of microorganisms such as filamentous fungi, bacteria and actinomycetes, which are alkalophilic microorganisms, as seeds, and mixing the soil improvement material with a highly alkaline soil, wherein the soil improvement material is Immediately before mixing with highly alkaline soil, activation promoting materials are mixed to promote the activity of the alkaliphilic microorganisms to improve the air permeability, water permeability and water retention of the highly alkaline soil. Lowering the soil pH, soil improvement wherein the changing the soil ready for planting.