Organic fertilizer for soil remediation and preparation method thereof

Abstract

The present invention provides an organic fertilizer for soil remediation, which, on the basis of adding biochar, is used in combination with chondroitin sulfate and citric acid to promote the adsorption and fixation of heavy metals in the soil, thereby further reducing the pollution of the soil. The present invention also provides a preparation method of the organic fertilizer.

Description

Technical Field

[0001] The invention relates to an organic fertilizer for soil remediation and a method for preparing the organic fertilizer. Background Art

[0002] With the development of industrialization, heavy metal pollution in soil has become a serious environmental problem. When the concentration of heavy metal elements in the soil, such as lead, chromium, cadmium, and mercury, exceeds a certain level, they will have a toxic effect on the soil, affecting the physical and chemical properties and biological characteristics of the soil, causing the deterioration of the soil ecological environment, and threatening food safety and human health. At present, the commonly used technology for soil heavy metal pollution remediation is to use biochar to improve the heavy metal contaminated soil.

[0003] Zhang Ying et al. (Research on the adsorption and fixation effect of biochar on heavy metal ions in farmland soil [J]. Environmental Science and Management, 2020, 45(10): 118-122.) found through research that adding biochar to the soil can alleviate the hazards of heavy metal pollution in the soil.

[0004] Wang Xuandong et al. (Effects of different biochars on soil Cd forms and plant absorption of Cd [J]. Energy Conservation and Environmental Protection, 2020(03):50-52.) found that different raw materials of biochar have different effects on the biological effectiveness of heavy metals in soil.

[0005] Although existing technologies have found that adding biochar to soil can improve heavy metal pollution, this improvement is limited. There is still a need to provide a technical solution with better technical effects to solve the problem of heavy metal pollution in soil. Summary of the invention

[0006] The present invention provides an organic fertilizer for soil remediation, which, on the basis of adding biochar, is used in combination with chondroitin sulfate and citric acid to promote the adsorption and fixation of heavy metals in the soil, thereby further reducing the pollution of the soil. The present invention also provides a preparation method of the organic fertilizer.

[0007] The specific technical solutions of the present invention are as follows.

[0008] An organic fertilizer for soil restoration comprises organic fertilizer, microbial agent, biochar, chondroitin sulfate and citric acid.

[0009] On the basis of the prior art, the present invention adopts a method of using biochar, chondroitin sulfate and citric acid in combination to further improve the repairing effect of the organic fertilizer on the soil. Among them, in addition to the adsorption and fixation effect of biochar on heavy metals, the added chondroitin sulfate has a certain chelating ability, which can form a stable complex with heavy metal ions in the soil, improve the adsorption amount and fixation effect of heavy metals, and reduce their mobility; moreover, chondroitin sulfate, as a natural polymer, can be biodegraded and will not bring additional pollution to the soil. Citric acid also has a certain chelating ability. Compared with chondroitin sulfate, although the chelating ability is slightly weaker, its molecule is relatively small and its mobility in the soil is slightly stronger, which is conducive to fixing the heavy metal ions that chondroitin sulfate cannot fix.

[0010] The organic fertilizer is livestock excrement that has been composted and fermented. It should be noted that the organic fertilizer is livestock excrement, but the livestock excrement cannot be directly used to prepare the organic fertilizer, but needs to go through a composting and fermentation step.

[0011] The microbial agent is selected from one or more of Bacillus subtilis, Trichoderma, Pseudomonas, Lactobacillus plantarum, Bacillus licheniformis, Bacillus coagulans and Bacillus megaterium.

[0012] The biochar is obtained by pyrolysis of one or more plant rhizomes, preferably, the plant rhizomes are rice platycodon and / or corn platycodon. The biochar can be prepared by a common method in the art or purchased commercially.

[0013] The chondroitin sulfate is selected from one or more of chondroitin sulfate A, chondroitin sulfate B, chondroitin sulfate C, chondroitin sulfate D, chondroitin sulfate E, chondroitin sulfate K, chondroitin sulfate T, chondroitin sulfate M, chondroitin sulfate L, chondroitin sulfate F, and chondroitin sulfate G, preferably chondroitin sulfate A and / or chondroitin sulfate C.

[0014] The molecular weight of the chondroitin sulfate is 10 to 30 kDa.

[0015] It should be noted that the chondroitin sulfate, no matter which subdivision category it belongs to, can be used in the present invention. However, among the common commercially available chondroitin sulfates, chondroitin sulfate A and chondroitin sulfate C are easier to obtain, and their cost is relatively low, so the present invention preferably uses these two chondroitin sulfates. In addition, the molecular weight of chondroitin sulfate also has a small impact on the technical effect. If the molecular weight is too small, the degradation rate of chondroitin sulfate is too fast, and it is not suitable to play the role of fixing heavy metals; if the molecular weight is too large, the biodegradability is weaker, and the decomposition time under natural conditions is longer, which is also not conducive to environmental protection. Therefore, purchasing commercially available products within the range of chondroitin sulfate types and molecular weights defined in the present invention can obtain better beneficial effects and relatively low costs.

[0016] In a preferred embodiment of the present invention, the relative weight parts of the following components are used:

[0017] The amount of the organic fertilizer is 100 parts by mass;

[0018] The amount of the microbial agent is 10 to 20 parts by weight;

[0019] The amount of biochar is 5 to 10 parts by weight;

[0020] The amount of chondroitin sulfate is 5 to 10 parts by weight;

[0021] The amount of citric acid used is 1 to 3 parts by weight.

[0022] The method for preparing the organic fertilizer comprises the following steps: uniformly mixing the organic fertilizer, microbial agent, biochar, chondroitin sulfate and citric acid to obtain the organic fertilizer.

[0023] The method for preparing conventional organic fertilizers is well known to those skilled in the art. Under the various technical characteristics defined in the present invention, the preparation process, parameters, additional raw materials, etc. not described in detail in the present invention can be carried out according to the commonly used methods in the art without affecting the implementation of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described below with reference to specific examples. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0025] The raw materials used in the examples and comparative examples of the present invention are as follows:

[0026] Soil samples: After natural air drying, remove foreign matter, and pass through a 4 mm sieve;

[0027] Microbial agents: Bacillus megaterium;

[0028] Biochar: obtained by anaerobic carbonization of corn platycodon at 600℃;

[0029] Chondroitin sulfate A: extracted from bovine bones, molecular weight 14kDa, Sichuan Huatang Jurui Biological;

[0030] Chondroitin sulfate C: fish extract, molecular weight 28kDa, Dibo Chemical;

[0031] Corn seeds: Jinxin Agricultural Technology Co., Ltd.;

[0032] Organic fertilizer: composted and fermented poultry and livestock manure, homemade.

[0033] Preparation of cadmium-containing soil samples: according to the cadmium content of 20mg*kg-1 The cadmium sulfate aqueous solution was added to the soil samples and aged for 2 months.

[0034] The preparation method of the organic fertilizer sample of the embodiment and the comparative example is: organic fertilizer, microbial agent, biochar, chondroitin sulfate (if any), citric acid (if any) are mixed uniformly to obtain a sample. The types and amounts of each raw material of the embodiment and the comparative example samples are listed in Table 1, based on the relative mass parts of each component.

[0035] Table 1 Amount of each raw material used in the examples and comparative examples (parts by mass)

[0036]

[0037]

[0038] Embodiment and comparative example Plant cultivation Corn was planted in an indoor potted form, and the amount of organic fertilizer used was 8% of the soil mass. The cadmium-containing soil was fertilized and sown, and the soil moisture and room temperature were kept suitable for corn growth during the experiment. After the corn seedlings grew out, they were grown for 80 days and then sampled and tested.

[0039] The root, stem and leaf of the corn sample were sampled, and the samples were placed in an oven at 105°C for 30 minutes, then dried at 80°C to constant weight, and taken out for cadmium content testing. The test method was carried out according to the method disclosed in "Determination of Cadmium in Plant Samples by Microwave Digestion ICP-MS" (Li Biao et al., Modern Scientific Instruments, 2011 (1): 112-113). The test results are listed in Table 2.

[0040] Table 2 Cadmium content of corn samples in Examples and Comparative Examples

[0041] category Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[root mg*kg -1 > 8.68 7.72 8.23 9.86 8.84 10.37 <![CDATA[Stem mg*kg -1 > 3.03 2.29 2.92 3.77 3.13 3.81 <![CDATA[Leaf mg*kg -1 > 5.05 4.87 5.04 5.91 5.16 5.92

[0042] It should be noted that the types and amounts of raw materials, process steps, etc. that are not described in the embodiments and comparative examples of the present invention all adopt the commonly used raw materials and processes in the field, and these undescribed contents remain consistent in the embodiments and comparative examples, do not affect the horizontal comparison of the embodiments and comparative examples, and do not affect the technical effects of the present invention.

Claims

1. An organic fertilizer for soil remediation, comprising the following raw materials in parts by weight: 100 parts of organic fertilizer, 20 parts of microbial agent, 10 parts of biochar, 10 parts of chondroitin sulfate C and 3 parts of citric acid; the organic fertilizer is poultry and livestock manure that has been composted and fermented; the microbial agent is Bacillus megaterium; the biochar is obtained by anaerobic carbonization treatment of corn platycodon at 600°C.

2. A method for preparing the organic fertilizer according to claim 1, characterized in that the steps include: The organic fertilizer, microbial agent, biochar, chondroitin sulfate C and citric acid are uniformly mixed to obtain the organic fertilizer.

Images