Method for synergistically reducing and repairing available cadmium in farmland soil by microorganisms and preventing and controlling cadmium in rice stems and leaves

Abstract

The invention discloses a farmland soil available cadmium microorganism synergistic decrement remediation and rice stem and leaf cadmium prevention and control method, which comprises the following steps: firstly, submerging a cadmium-polluted field to be remediated for 5-11 days, applying an inorganic remediation agent, carrying out rotary tillage and uniform mixing, applying a microbial remediation agent in the field after 2-7 days after the inorganic remediation agent is applied, carrying out treatment for 18-36 hours by the microbial remediation agent, then transplanting rice seedlings, and carrying out rotary tillage and uniform mixing. The rice stem and leaf cadmium blocking and controlling agent is sprayed in the rice growing period. The invention provides a farmland soil available cadmium microorganism synergistic decrement remediation and rice stem and leaf cadmium prevention and control technology, on one hand, functional microorganism bacteria (groups) are cooperated with an inorganic heavy metal ion mineralizer to reduce the content of available cadmium in soil through phase change of cadmium, and migration of the overground part of cadmium in the soil is reduced; on the other hand, migration and accumulation of cadmium in rice stems and leaves to rice grains are reduced through the rice stem and leaf cadmium blocking and controlling agent.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal contaminated soil remediation, and more specifically to a method for synergistic reduction and remediation of available cadmium in farmland soil by microorganisms and cadmium control in rice stems and leaves. Background Art

[0002] Heavy metal pollution in soil is the main factor threatening agricultural safety. Crops absorb heavy metals in the soil and enter the food chain. As the food chain circulates, these heavy metals will eventually accumulate in the human body, thus endangering human health. Cadmium is the main heavy metal pollution in soil. Therefore, it is extremely important to carry out research on the remediation of heavy metal cadmium pollution in farmland, establish a technical system for the environmental protection and comprehensive management of agricultural land soil, and ensure that the heavy metal content of agricultural products meets national quality standards, which is extremely important for ensuring food production and agricultural product safety.

[0003] Rice is an important food crop and is seriously contaminated by heavy metal cadmium. The essence of cadmium exceeding the standard in rice is that the biologically active cadmium (effective cadmium) in the topsoil is absorbed by the roots during the growth of rice and migrates to the stems and leaves through the xylem. After accumulation, it migrates and accumulates in rice through the phloem of the stems and leaves. Moreover, during the entire rice growth period, the migration, distribution and total amount of cadmium in rice are a dynamic process.

[0004] The current mainstream technology for in-situ passivation remediation of cadmium-contaminated farmland soil is to add functional materials with a series of functions such as ion exchange adsorption, precipitation, redox and complexation (chelation) to the soil, so that the biologically active cadmium ions in the soil are converted into a state with less biological activity (passivation, solidification, mineralization), thereby reducing the absorption of cadmium in the soil by crops (aboveground migration) and achieving the purpose of soil remediation. For example, the solidification / stabilization soil heavy metal remediation technology of the United Kingdom, the United States and other countries (which has been developed and widely used for decades), and the "An ion mineralization stabilizer and use method for treating heavy metal contaminated soil" of Hunan Yongqing Environmental Restoration Co., Ltd. in my country (national protection technology, Chinese patent C09K17 / 06GK102766465SQ20121026770, published on November 7, 2012) are representatives of this type of technology. Due to the nature of the soil, type of pollution, degree of pollution, type of crops and agronomic measures, this type of technology is difficult to achieve the expected results in terms of effectiveness, durability and economy in actual soil remediation, and therefore it is difficult to meet planting needs. Therefore, how to provide a new method is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] In view of this, the present invention provides a technology for the synergistic reduction and restoration of effective cadmium in farmland soil by microorganisms and the cadmium control in rice stems and leaves. On the one hand, functional microbial bacteria (groups) are used in collaboration with inorganic heavy metal ion mineralizers to reduce the effective cadmium content in the soil through phase change of cadmium and reduce the aboveground migration of cadmium in the soil. On the other hand, rice stem and leaf cadmium inhibitors are used to reduce the migration and accumulation of cadmium in rice stems and leaves to its grains.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A method for reducing and repairing the available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves, comprising the following steps:

[0008] (1) Flood the cadmium-contaminated field to be repaired for 5-11 days, apply an inorganic repair agent, and till and mix thoroughly;

[0009] (2) After the inorganic remediation agent is applied to the field, the microbial remediation agent is applied 2-7 days later;

[0010] (3) transplanting rice seedlings 18-36 hours after the treatment in step (2);

[0011] (4) Spray cadmium inhibitors on rice stems and leaves during the rice growth period.

[0012] Preferably, the inorganic repairing agent includes any one or more of lime and sodium silicate.

[0013] Furthermore, the weight ratio of the amount of the inorganic remediation agent to the effective cadmium content in the soil to be treated for cadmium contamination is (110-301):1.

[0014] Preferably, the microbial remediation agent includes photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus in a weight ratio of 1:(1-3):(1-5):(1-6).

[0015] Furthermore, the total amount of live bacteria in the microbial remediation agent is 5.7×10 9 -1.33×10 10 cfu / ml.

[0016] Furthermore, the weight ratio of the amount of the microbial remediation agent to the effective cadmium content in the soil to be treated for cadmium pollution is (0.5-6.5):1.

[0017] Preferably, the rice stem and leaf cadmium inhibitor includes sodium metasilicate pentahydrate, urea, potassium humate, potassium dihydrogen phosphate, zinc sulfate, a surfactant, trace elements and water.

[0018] Furthermore, the components of the rice stem and leaf cadmium inhibitor include, by mass, 310-440 parts of sodium metasilicate pentahydrate, 28-46 parts of urea, 1-7 parts of potassium humate, 89-113 parts of potassium dihydrogen phosphate, 1-13 parts of zinc sulfate, 3-16 parts of surfactants, 1-11 parts of trace elements and 470-620 parts of water.

[0019] Furthermore, the surfactant is mainly any one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate and sorbitan oleate, and the trace elements include any one or more of iron, manganese, copper, boron, molybdenum, chlorine and sodium.

[0020] Preferably, in step (4), the spraying is performed at any one or more of the late tillering stage, jointing-booting stage and heading stage of rice, and each stage is sprayed 2-3 times, with an interval of 2-6 days between each spraying; the weight ratio of the amount of the rice stem and leaf cadmium inhibitor to the effective cadmium content in the soil to be treated for cadmium pollution is (0.01-0.5):1.

[0021] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method for synergistic reduction and restoration of effective cadmium in farmland soil by microorganisms and cadmium control in rice stems and leaves, which has the following beneficial effects:

[0022] The present invention adopts a mixture of inorganic and organic reagents. On the one hand, functional microorganisms (groups) cooperate with inorganic heavy metal ion mineralizers to reduce the effective cadmium content in the soil through the phase change of cadmium, reduce the migration of cadmium in the aboveground part of the soil, and on the other hand, reduce the migration and accumulation of cadmium in the rice stems and leaves to its grains through cadmium barrier control in rice stems and leaves. This technology can effectively achieve the same-year repair and solve the problem of rice cadmium production safety in the same year. The mineral-derived materials, beneficial soil microbial flora, humus, etc. involved in the technical system are beneficial components of the soil and nutrients necessary for the growth of crops. Therefore, it is a method for ecological restoration of cadmium-contaminated farmland soil. This technology effectively and economically achieves not affecting agricultural production, not reducing soil production functions, reducing pollutants from entering the edible part of crops, and ensuring the quality and safety of agricultural products. The technology is at the advanced level of the industry and has obvious technical and economic advantages compared with the passivation technology commonly used in the industry. Its demonstration and promotion have significant economic and social benefits. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] The effective soil cadmium reduction repair agent includes an inorganic repair agent and a microbial repair agent, wherein, by weight, the inorganic repair agent includes: 60 parts of lime, 20 parts of sodium silicate, and the microbial repair agent includes 2 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and the total amount of live bacteria is 1×10 10 cfu / ml.

[0026] Example 2

[0027] The effective soil cadmium reduction remediation agent includes an inorganic remediation agent and a microbial remediation agent, wherein, by weight, the inorganic remediation agent includes: 60 parts of lime, 30 parts of sodium silicate, and the microbial remediation agent includes 3 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and the total amount of live bacteria is 1×10 10 cfu / ml.

[0028] Example 3

[0029] The effective soil cadmium reduction remediation agent includes an inorganic remediation agent and a microbial remediation agent, wherein, by weight, the inorganic remediation agent includes: 60 parts of lime, 40 parts of sodium silicate, and the microbial remediation agent includes 4 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and a total amount of live bacteria of 1×10 10 cfu / ml.

[0030] Example 4

[0031] The effective soil cadmium reduction repair agent includes an inorganic repair agent and a microbial repair agent, wherein, by weight, the inorganic repair agent includes: 70 parts of lime, 20 parts of sodium silicate, and the microbial repair agent includes 3 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and the total amount of live bacteria is 1×10 10 cfu / ml.

[0032] Example 5

[0033] The effective soil cadmium reduction remediation agent includes an inorganic remediation agent and a microbial remediation agent, wherein, by weight, the inorganic remediation agent includes: 70 parts of lime, 30 parts of sodium silicate, and the microbial remediation agent includes 4 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and the total amount of live bacteria is 1×10 10 cfu / ml.

[0034] Example 6

[0035] The effective soil cadmium reduction remediation agent includes an inorganic remediation agent and a microbial remediation agent, wherein, by weight, the inorganic remediation agent includes: 70 parts of lime, 40 parts of sodium silicate, and the microbial remediation agent includes 4 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and a total amount of live bacteria of 1×10 10 cfu / ml.

[0036] Example 7

[0037] The effective soil cadmium reduction remediation agent includes an inorganic remediation agent and a microbial remediation agent, wherein, by weight, the inorganic remediation agent includes: 80 parts of lime, 20 parts of sodium silicate, and the microbial remediation agent includes 4 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and a total amount of live bacteria of 1×10 10 cfu / ml.

[0038] Example 8

[0039] The effective soil cadmium reduction remediation agent includes an inorganic remediation agent and a microbial remediation agent, wherein, by weight, the inorganic remediation agent includes: 80 parts of lime, 30 parts of sodium silicate, and the microbial remediation agent includes 2 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and bacillus composite agents, with a weight ratio of 1:1:1:1, and the total amount of live bacteria is 1×10 10 cfu / ml.

[0040] Example 9

[0041] The effective soil cadmium reduction remediation agent includes an inorganic remediation agent and a microbial remediation agent, wherein, by weight, the inorganic remediation agent includes: 80 parts of lime, 40 parts of sodium silicate, and the microbial remediation agent includes 3 parts of microbial agents, which are photosynthetic bacteria, yeast, lactic acid bacteria and Bacillus composite agents, with a weight ratio of 1:1:1:1, and the total amount of live bacteria is 1×10 10 cfu / ml.

[0042] Experimental Example 1

[0043] Examples 1-9 are different formulations of soil effective cadmium reduction and restoration agents. The soil comes from Berlin Village, Xiushui Town, Mianyang, Sichuan. Table 1 shows the effect of reducing effective cadmium in the soil after using Examples 1-9.

[0044] Table 1 Effect of reducing the amount of available cadmium in soil after using Examples 1-9

[0045]

[0046] Example 10

[0047] A method for the synergistic reduction and restoration of effective cadmium in soil by microorganisms and cadmium control in rice stems and leaves. After flooding a field contaminated by heavy metal cadmium for 7 days, an inorganic repair agent in an effective cadmium reduction and restoration agent for soil is applied, and rotary tillage and mixing are performed; after 4 days, a microbial repair agent in the effective cadmium reduction and restoration agent for soil is applied; after 24 hours, rice seedlings are transplanted; during the rice tillering period, the rice stems and leaves cadmium control agent is sprayed on the field that needs cadmium control, and the spraying is performed twice in each period, with an interval of 3 days between each spraying. The soil effective cadmium reduction and restoration agent adopts the composition and ratio described in Example 8, the inorganic restoration agent in the soil effective cadmium reduction and restoration agent is applied at 294.6 kg / mu, and the microbial restoration agent is applied at 5.4 kg / mu; the components in the rice stem and leaf cadmium inhibitor are calculated by mass as follows: 320 parts of sodium metasilicate pentahydrate, 32 parts of urea, 3 parts of potassium humate, 100 parts of potassium dihydrogen phosphate, 5 parts of zinc sulfate, 5 parts of sodium dodecyl sulfate, 5 parts of trace element iron and 530 parts of water; the rice stem and leaf cadmium inhibitor is applied at 30 ml / mu·time, and before application, it is diluted with water to 300 ml and then sprayed.

[0048] Embodiment 11

[0049] A method for the synergistic reduction and restoration of effective cadmium in soil by microorganisms and cadmium control in rice stems and leaves, comprising: applying an inorganic repair agent in an effective cadmium reduction and restoration agent in the soil after flooding a cadmium-contaminated field for 7 days, and rotary tilling and mixing; applying a microbial repair agent in the effective cadmium reduction and restoration agent in the soil after 4 days; transplanting rice seedlings 24 hours later; and spraying the rice stems and leaves cadmium control agent in the rice jointing-booting stage in the field that needs cadmium control, with two sprayings in each period, with an interval of 3 days between each spraying. The soil effective cadmium reduction and restoration agent adopts the composition and ratio described in Example 8, the inorganic restoration agent in the soil effective cadmium reduction and restoration agent is applied at 294.6 kg / mu, and the microbial restoration agent is applied at 5.4 kg / mu; the components in the rice stem and leaf cadmium inhibitor are calculated by mass as follows: 320 parts of sodium metasilicate pentahydrate, 32 parts of urea, 3 parts of potassium humate, 100 parts of potassium dihydrogen phosphate, 5 parts of zinc sulfate, 5 parts of sodium dodecylbenzene sulfonate, 5 parts of trace element copper and 530 parts of water; the rice stem and leaf cadmium inhibitor is applied at 30 ml / mu·time, and before application, it is diluted with water to 300 ml and then sprayed.

[0050] Example 12

[0051] A method for the synergistic reduction and restoration of effective cadmium in soil by microorganisms and cadmium control in rice stems and leaves, comprising: applying an inorganic repair agent in an effective cadmium reduction and restoration agent in the soil after flooding a cadmium-contaminated field for 7 days, and rotary tilling and mixing; applying a microbial repair agent in the effective cadmium reduction and restoration agent in the soil after 4 days; transplanting rice seedlings 24 hours later; and spraying the rice stems and leaves cadmium control agent in the rice jointing-booting stage and the heading stage for the field that needs cadmium control, with two sprayings in each period, with an interval of 3 days between each spraying. The soil effective cadmium reduction and repair agent adopts the composition and ratio described in Example 8, the inorganic repair agent in the soil effective cadmium reduction and repair agent is applied at 294.6 kg / mu, and the microbial repair agent is applied at 5.4 kg / mu; the components in the rice stem and leaf cadmium inhibitor are calculated by mass as follows: 320 parts of sodium metasilicate pentahydrate, 32 parts of urea, 3 parts of potassium humate, 100 parts of potassium dihydrogen phosphate, 5 parts of zinc sulfate, 5 parts of sorbitan oleate, 5 parts of trace elements sodium and 530 parts of water; the rice stem and leaf cadmium inhibitor is applied at 30 ml / mu·time, and before application, it is diluted with water to 300 ml and then sprayed.

[0052] Embodiment 13

[0053] A method for the synergistic reduction and restoration of effective cadmium in soil by microorganisms and cadmium control in rice stems and leaves, comprising: applying an inorganic repair agent in an effective cadmium reduction and restoration agent in the soil after flooding a cadmium-contaminated field for 7 days, and rotary tilling and mixing; applying a microbial repair agent in the effective cadmium reduction and restoration agent in the soil after 4 days; transplanting rice seedlings 24 hours later; and spraying the rice stems and leaves cadmium control agent in the rice jointing-booting stage and the heading stage for the field that needs cadmium control, with two sprayings in each period, with an interval of 3 days between each spraying. The soil effective cadmium reduction and restoration agent adopts the composition and proportion described in Example 8, wherein the inorganic restoration agent in the soil effective cadmium reduction and restoration agent is applied at 196.4 kg / mu, and the microbial restoration agent is applied at 3.6 kg / mu; the components in the rice stem and leaf cadmium inhibitor are calculated by mass as follows: 320 parts of sodium metasilicate pentahydrate, 32 parts of urea, 3 parts of potassium humate, 100 parts of potassium dihydrogen phosphate, 5 parts of zinc sulfate, 5 parts of sodium dodecyl sulfate, 5 parts of trace element boron and 530 parts of water; the rice stem and leaf cadmium inhibitor is applied at 30 ml / mu·time, and before application, it is diluted with water to 300 ml and then sprayed.

[0054] Experimental Example 2

[0055] Examples 10-12 are about spraying rice stem and leaf cadmium inhibitors at different stages of rice growth, and Examples 12-13 are about different application amounts of soil effective cadmium reduction and restoration agents. Table 2 is the results of soil effective cadmium and rice cadmium reduction in Examples 10-13.

[0056] Table 2 Results of reduction of available cadmium in soil and cadmium in rice in Examples 10-13

[0057]

[0058]

[0059] The above implementation results show that the pH value of the restored farmland soil is about 7.1 when the rice is fully mature, and the effective cadmium in the soil is reduced by 45%-48%, among which the water-soluble cadmium is reduced by 92.71%, the ion-exchange cadmium is reduced by 54.17%, the carbonate-bound cadmium is increased by 3.37 times, the humic acid-bound cadmium is increased by 1.23 times, the iron-manganese-bound cadmium is basically unchanged, the strongly organic-bound cadmium is increased by 1.61 times, and the residual cadmium is increased by 1.38 times; this method effectively and economically achieves the problem of "not affecting agricultural production, not reducing soil production function, reducing pollutants entering the edible part of crops, and ensuring the quality and safety of agricultural products." When the rice is fully mature, the cadmium content in rice roots decreases by 72% to 81%, the cadmium content in rice stems and leaves decreases by 74% to 84%, and the cadmium content in brown rice decreases by 75% to 85%. The cadmium content in brown rice is 0.14 mg / kg to 0.12 mg / kg (national standard: the cadmium content in brown rice is 0.2 mg / kg).

[0060] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will comply with the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A method for reducing and repairing the available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves, characterized in that: The following steps are involved: (1) Flood the cadmium-contaminated field to be repaired for 5-11 days, apply an inorganic repair agent, and till and mix thoroughly; (2) After the inorganic remediation agent is applied to the field, the microbial remediation agent is applied 2-7 days later; (3) transplanting rice seedlings 18-36 hours after the treatment in step (2); (4) Spray cadmium inhibitors on rice stems and leaves during the rice growth period.

2. The method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to claim 1, characterized in that: The inorganic repairing agent includes any one or more of lime and sodium silicate.

3. A method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to any one of claims 1 or 2, characterized in that: The weight ratio of the amount of the inorganic remediation agent to the effective cadmium content in the soil to be treated for cadmium pollution is (110-301):

1.

4. The method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to claim 1, characterized in that: The microbial repair agent comprises photosynthetic bacteria, yeast, lactic acid bacteria and bacillus in a weight ratio of 1:(1-3):(1-5):(1-6).

5. The method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to claim 4, characterized in that: The total amount of live bacteria in the microbial remediation agent is 5.7×10 9 -1.33×10 10 cfu / ml.

6. A method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to any one of claims 1 or 4, characterized in that: The weight ratio of the amount of the microbial remediation agent to the effective cadmium content in the soil to be treated for cadmium pollution is (0.5-6.5):

1.

7. The method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to claim 1, characterized in that: The rice stem and leaf cadmium inhibitor comprises sodium metasilicate pentahydrate, urea, potassium humate, potassium dihydrogen phosphate, zinc sulfate, a surfactant, trace elements and water.

8. The method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to claim 7, characterized in that: The components of the rice stem and leaf cadmium inhibitor include, by mass, 310-440 parts of sodium metasilicate pentahydrate, 28-46 parts of urea, 1-7 parts of potassium humate, 89-113 parts of potassium dihydrogen phosphate, 1-13 parts of zinc sulfate, 3-16 parts of surfactant, 1-11 parts of trace elements and 470-620 parts of water.

9. The method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to claim 7, characterized in that: The surfactant is any one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate and sorbitan oleate, and the trace elements include any one or more of iron, manganese, copper, boron, molybdenum, chlorine and sodium.

10. The method for reducing and repairing available cadmium in farmland soil by microorganisms and controlling cadmium in rice stems and leaves according to claim 1, characterized in that: In step (4), spraying is performed at any one or more stages of the rice tillering stage, jointing-booting stage and heading stage, with each stage spraying 2-3 times, with an interval of 2-6 days between each spraying; The weight ratio of the amount of rice stem and leaf cadmium inhibitor to the effective cadmium content in the soil to be treated for cadmium pollution is (0.01-0.5):1.

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