Microbial agent for reducing pesticide residues in soil

Abstract

The invention relates to the technical field of microbial preparations for agricultural environment restoration, and provides a microbial agent for reducing pesticide residues in soil, which is characterized by comprising the following components in parts by weight: 30-60 parts of ochrobactrum having viable count of more than or equal to 5 * 10 < 8 > cfu / g; the spore number is greater than or equal to 2 * 10 < 8 > cfu / g. The final residues of imidacloprid and difenoconazole in the compounded microbial agent are reduced to about 0.20 mg / kg, balanced and efficient removal is realized, and the possible unbalance situation of'degrading one pesticide and remaining one pesticide 'in the traditional method is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of agricultural environment remediation, and particularly relates to a microbial agent for reducing pesticide residues in soil. BACKGROUND

[0002] In the greenhouse tomato planting, imidacloprid and difenoconazole are widely used in key growth periods because of their significant prevention and control effects. In the seedling stage, 5:1 ratio of imidacloprid and difenoconazole is used to prevent and control damping-off and whitefly; in the fruit setting stage, 3:2 ratio of imidacloprid and difenoconazole is used to prevent and control botrytis and thrips; and before harvesting, 1:4 ratio of imidacloprid and difenoconazole is used to control anthracnose and aphids, which are the core pesticide combinations to ensure the yield and quality of tomatoes. However, long-term directional use of the pesticide combinations leads to continuous accumulation of residues of the two pesticides in the soil. On the one hand, the residual pesticides can destroy the soil microbial community structure, reduce soil fertility, cause the growth of tomato roots to be hindered and the stress resistance to decrease, and further cause yield reduction and quality deterioration; on the other hand, the pesticide residues in the soil are easy to be absorbed into tomato fruits through the roots, which poses a risk to food safety, and may also penetrate or leach with irrigation water to pollute the surrounding water and soil environment, which is contrary to the demand for green agricultural development. At present, the main treatment means for the pesticide residues in the soil of the greenhouse tomatoes in the region is physical ploughing (such as deep ploughing for dilution) or chemical degradation agent (such as oxidizing agent), but the physical method can only achieve residue transfer and cannot completely degrade the residues, and is easy to damage the soil aggregate structure; the chemical method has a high degradation efficiency, but is easy to introduce new chemical pollutants, further aggravating the burden on the soil environment, and is difficult to meet the soil remediation needs of long-term continuous cropping of greenhouse tomatoes. Therefore, it is a key to solve the current pesticide residue problem and ensure the sustainable development of the tomato industry to develop a microbial agent that can efficiently and safely degrade the residues of imidacloprid and difenoconazole in the soil. SUMMARY

[0003] The present application aims to overcome the deficiencies of the prior art, and provides a microbial agent for reducing pesticide residues in soil to solve the above technical problems.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A microbial agent for reducing pesticide residues in soil, characterized in that the following components are included by weight parts: Ochrobactrum 30-60 parts, viable bacterial count ≥ 5×10 8 cfu / g; Aspergillus fumigatus 20-40 parts, spore count ≥ 2×10 8 cfu / g.

[0005] Further, the microbial agent further includes, Bacillus mucilaginosus and Trichoderma viride 10-30 parts, wherein the mass ratio of Bacillus mucilaginosus and Trichoderma viride is 1.2-1.5:0.5-0.8, the viable count of Bacillus mucilaginosus is ≥ 1×10 9 cfu / g, and the spore count of Trichoderma viride is ≥ 1×10 8 cfu / g. Bradyrhizobium sp. and photosynthetic bacteria 10-30 parts, wherein the ratio of Bradyrhizobium sp. and photosynthetic bacteria is 1:1.0-1.2, and the viable count of Bradyrhizobium sp. and photosynthetic bacteria is both ≥ 5×10 8 cfu / g.

[0006] Further, the ratio of the Ochrobactrum and Aspergillus fumigatus is 5:3.

[0007] Further, the ratio of the two groups of bacteria of Bacillus mucilaginosus and Trichoderma viride and Bradyrhizobium sp. and photosynthetic bacteria is 1:1.

[0008] Further, the ratio of the Ochrobactrum, Aspergillus fumigatus, Bacillus mucilaginosus and Trichoderma viride, Bradyrhizobium sp. and photosynthetic bacteria is 5:3:2:2.

[0009] Further, the microbial agent further comprises a mature organic fertilizer, and the ratio is as follows: the agent 5-15 parts; the mature organic fertilizer 1000 parts, wherein the agent is composed of Ochrobactrum, Aspergillus fumigatus, Bacillus mucilaginosus and Trichoderma viride, Bradyrhizobium sp. and photosynthetic bacteria.

[0010] The beneficial effects of the present application are as follows: The Ochrobactrum degrades the residual imidacloprid, and eliminates the neurotoxicity of imidacloprid to insects and microorganisms; the Aspergillus fumigatus decomposes the heterocyclic structure of difenoconazole by using its strong enzyme system, and breaks the chemical stability of difenoconazole; the Bacillus mucilaginosus rapidly improves the soil compaction problem caused by long-term use of pesticides after the pesticide toxicity is eliminated; the photosynthetic bacteria improves the energy level and activity of the entire microbial community; the Bradyrhizobium sp. promotes the growth of plant roots and reconstructs the root-soil interaction system after the soil is "detoxified"; and the Trichoderma viride introduces beneficial antagonistic bacteria to rebuild a healthy soil microbial balance and prevent disease rebound after difenoconazole inhibits part of the pathogenic bacteria.

[0011] In the compound contaminated soil with the final residual ratio close to 1:1, the microbial agent of the present application reduces the final residue of the two pesticides to about 0.20 mg / kg, realizes balanced and efficient removal, and avoids the imbalance situation that may occur in the traditional method, i.e., "degrading one kind and remaining one kind". DETAILED DESCRIPTION

[0012] The present application is further described in detail by specific examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application. Embodiment

[0013] A microbial agent for reducing pesticide residues in soil, comprising the following components by weight parts: Agent 12 parts; Composted organic fertilizer 1000 parts; Wherein, 12 parts of the agent specifically includes Ochrobactrum 5 parts, viable bacteria ≥ 5×10 8 cfu / g; Aspergillus fumigatus 3 parts, spore number ≥ 2×10 8 cfu / g; Bacillus mucilaginosus and Trichoderma viride 2 parts, wherein the mass ratio of Bacillus mucilaginosus and Trichoderma viride is 1.5:0.5, the viable bacteria of Bacillus mucilaginosus is ≥ 1×10 9 cfu / g, and the spore number of Trichoderma viride is ≥ 1×10 8 cfu / g; Azospirillum brasilense and photosynthetic bacteria 2 parts, wherein the ratio of Azospirillum brasilense and photosynthetic bacteria is 1:1, the viable bacteria of Azospirillum brasilense and the viable bacteria of photosynthetic bacteria are both ≥ 5×10 8 cfu / g.

[0014] Ochrobactrum (BaP-20-3) Culture medium: tryptone 15g, soybean peptone 5g, NaCl 5g, agar 15g, water 1L, pH 7.1-7.2 Culture conditions: temperature 28-30℃, shaking speed 180-200rpm, culture for 18-24h.

[0015] Bacillus mucilaginosus (1480D) Culture medium: sucrose 10g, yeast extract 0.5g, K2HPO4 0.5g, MgSO4 0.2g, water 1L, pH 7.2-7.5 Culture conditions: temperature 28-32℃, static culture, culture for 24-48h.

[0016] Azospirillum brasilense (ATCC 29145) Culture medium: KH2PO4 0.4g, K2HPO4 0.1g, MgSO4·7H2O 0.2g, NaCl 0.1g, CaCl2 0.02g, FeCl3 0.01g, Na2MoO4·2H2O 0.002g, sodium malate 5.0g, yeast extract 0.05g, pH 7.2-7.4 Culture conditions: temperature 28-30℃, shaking speed 150rpm, culture for 36-48h.

[0017] Photosynthetic bacteria (R. palustris, CICC 23812) Culture medium: sodium acetate 3g, peptone 1g, yeast extract 0.5g, KH2PO4 0.3g, water 1L, pH 7.0-7.5; Culture conditions: temperature 25-30℃, light intensity 2000-3000lux, culture for 48-72h.

[0018] Aspergillus fumigatus (746128) Culture medium: sucrose 30.0g, NaNO3 3.0g, MgSO4·7H2O 0.5g, KCl 0.5g, FeSO4·4H2O 0.01g, K2HPO4 1.0g, agar 15.0g, water 1.0L, pH 6.0-6.5.

[0019] Culture conditions: temperature 25-28℃, dark or weak light environment, culture for 5-7d, until a large number of black spores form on the surface of the culture medium.

[0020] Trichoderma virens (IEDAF310) Culture medium: potato 200g (peeled and boiled, filtered), glucose 20g, agar 15-20g, water 1L, pH natural.

[0021] Culture conditions: temperature 25-30℃, light (12h light / 12h dark alternation), culture for 4-6d, until a green spore layer appears on the surface.

[0022] The preparation process of the matured organic fertilizer is as follows: 1. Raw material treatment Crushing the raw materials: crush the straw to 2-5cm; Mixing the raw materials: mix corn straw 70% and cow dung 30% by mass percentage, and control the moisture content at 50%-60%; Adjusting the pH: control the pH of the mixed raw materials at 7.0-8.0; 2. Heap fermentation Warming-up stage (1-7th day) Heap shape: form a trapezoidal or rectangular shape, with a bottom width of 1.5-2m and a height of 1-1.2m, and cover the top of the heap with plastic film (leave a small number of air holes); High-temperature stage (7-21th day) Turning time: When the pile temperature rises to 60-70℃, keep for 2-3 days, then turn the outer layer (low temperature area) to the inside for the first time, and turn the inner layer to the outer layer to ensure uniform heating; Turning frequency: Turn the pile once every 5-7 days afterwards, a total of 3-4 times, and supplement water during turning to maintain a water content of about 50%; Cooling and decomposition stage (21-30 days) The pile temperature gradually decreases to 30-40℃, and the pile color turns brown or black, with no raw material odor and a small amount of white mycelium.

[0023] Operation: Stop turning, cover with plastic film to seal, and let the pile naturally decompose for 10-15 days to further stabilize the organic matter and avoid subsequent secondary fermentation.

[0024] Mixing of microbial agents and decomposed organic fertilizer in microbial agents: First mix bacteria and decomposed organic fertilizer, stir for 30 min, and stand for 1 h; then add fungal spore solution and further stir for 30 min.

[0025] Application Example 1 Test soil: Collected from clean farmland soil that has not used the two pesticides, adding imidacloprid and difenacoum to the soil, imidacloprid 1.2 mg / kg, difenacoum 1.15 mg / kg.

[0026] Experimental design: CK (blank control): No addition of any repair agent.

[0027] T-Traditional (traditional single microbial agent): Adding A or B alone, with a total amount of bacteria equivalent to that of the present application group.

[0028] T-Imbalance 1 (imbalance ratio group): Organic fertilizer: A: B: C: D = 1000:8:2:2:2.

[0029] T-Imbalance 2 (imbalance ratio group): Organic fertilizer: A: B: C: D = 1000:2:4:2:2.

[0030] T-Invention 1: Using the ratio of organic fertilizer optimized for this complex pollution feature: A: B: C: D = 1000:5:3:2:2.

[0031] T-Invention 2: Using the ratio of organic fertilizer optimized for this complex pollution feature: A: B: C: D = 1000:6:2:1:1.

[0032] T-invention 3: Using the proportioned organic fertilizer optimized for this complex pollution feature: A : B : C : D = 1000 : 3 : 4 : 1 : 3.

[0033] T-invention 4: Using the proportioned organic fertilizer optimized for this complex pollution feature: A : B : C : D = 1000 : 5 : 3 : 3 : 3.

[0034] T-invention 5: Using the proportioned organic fertilizer optimized for this complex pollution feature: A : B : C : D = 1000 : 3 : 4 : 3 : 1.

[0035] A: Ochrobactrum ; B: Aspergillus fumigatus; C: Bacillus mucilaginosus and Trichoderma viride; D: Azospirillum brasilense and Photosynthetic bacteria.

[0036] Culture and detection: Each repair agent is thoroughly mixed with the simulated contaminated soil, and cultured under controllable conditions (25°C, humidity 60%) for 60 days. Samples are taken at 0, 30, 60 days, and the residual amount of two pesticides is detected.

[0037] 3. Experimental results Remediation effect of combined medication on complex contaminated soil (pesticide residue concentration, mg / kg)

[0038] Note: Comprehensive degradation rate = [1 - ( (final imidacloprid + final difenacloprid) / (initial imidacloprid + initial difenacloprid) )] x 100%.

[0039] Overall repair ability for complex pollution: The comprehensive degradation rate of T-invention 1 of the present application for the two pesticides at the end of the experiment was as high as 83.3%, which was significantly higher than that of the traditional single bacterial agent (47.1%, 49.7%) and the unbalanced proportioning group (65.4%). This proves that the modular system of the present application has excellent and balanced overall repair ability for complex pesticide residues with complex proportions actually produced in the field.

[0040] Key role of proportion optimization: The T-imbalance groups (8:2 and 2:4) degraded one of the pesticides faster in the early stage, but the degradation of the other pesticide always lagged behind. In contrast, the T-invention 1 (5:3) degraded both pesticides synchronously and efficiently, and the final residual concentrations were both reduced to the safe level of about 0.20 mg / kg. This proves the superiority of the balanced degradation strategy for complex pollutants and the scientificity and necessity of the ratio (5:3) of the present application in this scenario.

[0041] This example proves that the modular microbial remediation agent (ratio 1000:5:3:2:2) of the present application can efficiently and synchronously degrade the complex residues of imidacloprid and difenconazole produced by joint use, and its remediation effect is significantly better than that of traditional single bacterial agent and unbalanced compound bacterial agent. The specific ratio is the key to achieving the best remediation effect for such complex contaminated soil.

[0042] It should be noted that in this document, the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0043] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A microbial inoculant for reducing pesticide residues in soil, characterized by, By weight parts, including the following components: Xanthomonas 30-60 parts, viable bacterial count ≥ 5 x 10 8 cfu / g; Aspergillus fumigatus 20-40 parts, spore number ≥ 2 x 10 8 cfu / g.

2. The microbial inoculant of claim 1, wherein, The microbial agent also includes, Bacillus mucilaginosus and Trichoderma viride 10-30 parts, wherein the mass ratio of Bacillus mucilaginosus and Trichoderma viride is 1.2-1.5:0.5-0.8, the viable count of Bacillus mucilaginosus is ≥1×109cfu / g, and the spore count of Trichoderma viride is ≥1×108cfu / g; Azospirillum brasilense and photosynthetic bacteria 10-30 parts, wherein the ratio of Azospirillum brasilense and photosynthetic bacteria is 1:1.0-1.2, and the viable count of Azospirillum brasilense and photosynthetic bacteria is ≥5×108cfu / g.

3. The microbial inoculant of claim 2, wherein, The ratio of the said Ochrobactrum and Aspergillus fumigatus is 5:

3.

4. The microbial inoculant of claim 2, wherein The ratio of the said Bacillus mucilaginosus and Trichoderma viride, Azospirillum brasilense and photosynthetic bacteria is 1:

1.

5. The microbial inoculant of claim 2, wherein The ratio of the said Ochrobactrum, Aspergillus fumigatus, Bacillus mucilaginosus and Trichoderma viride, Azospirillum brasilense and photosynthetic bacteria is 5:3:2:

2.

6. The microbial inoculant of claim 5, wherein The microbial agent also includes a mature organic fertilizer, and the ratio is as follows: microbial agent 5-15 parts; mature organic fertilizer 1000 parts, wherein the microbial agent is composed of Ochrobactrum, Aspergillus fumigatus, Bacillus mucilaginosus and Trichoderma viride, Azospirillum brasilense and photosynthetic bacteria.

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