阅读说明：本技术 一种包衣缓释肥及其在阻控重金属镉吸收和减少氮素流失中的应用 (Coated slow-release fertilizer and application thereof in inhibiting absorption of heavy metal cadmium and reducing loss of nitrogen ) 是由 周胜 张继宁 张鲜鲜 诸海焘 孙会峰 于 2019-08-21 设计创作，主要内容包括：本发明公开一种包衣缓释肥及其在阻控重金属镉吸收和减少氮素流失中的应用,属于土壤修复改良技术领域,公开一种包衣缓释肥在阻控重金属镉吸收和减少氮素流失中的应用,该包衣缓释肥的包衣为硫包衣、磷包衣或矿石粉包衣,所述矿石粉包衣中的矿石粉为凹凸棒矿石粉；本发明将包衣缓释肥施用于镉污染土壤后,修复效果理想,不仅显著降低土壤和农作物中镉含量,而且同时减少土壤中氮素流失。此外,由于一次性施用量小,一般为10-50kg/hm<Sup>2</Sup>,可以显著降低运输成本和施用成本,适宜大面积推广。(The invention discloses a coated slow-release fertilizer and application thereof in inhibiting absorption of heavy metal cadmium and reducing nitrogen loss, belongs to the technical field of soil remediation and improvement, and discloses application of the coated slow-release fertilizer in inhibiting absorption of heavy metal cadmium and reducing nitrogen loss, wherein the coating of the coated slow-release fertilizer is a sulfur coating, a phosphorus coating or a mineral powder coating, and the mineral powder in the mineral powder coating is attapulgite mineral powder; after the coated slow-release fertilizer is applied to the cadmium-polluted soil, the repairing effect is ideal, the cadmium content in the soil and crops is obviously reduced, and the nitrogen loss in the soil is reduced. In addition, the application amount is generally 10-50kg/hm because of small application amount at one time 2 The transportation cost and the application cost can be obviously reduced, and the method is suitable for large-area popularization.)

1. An application of a coated slow release fertilizer in preventing and controlling heavy metal cadmium absorption and reducing nitrogen loss.

2. The use of claim 1, wherein the coating comprises a sulfur coating, a phosphorous coating, or a mineral powder coating.

3. The use of claim 2, wherein the mineral powder in the mineral powder coating is attapulgite mineral powder.

4. Use according to claim 2, wherein the sulphur coating comprises sulphur urea, sulphur, potassium chloride sulphate and/or diammonium sulphate.

Technical Field

The invention relates to the technical field of soil remediation and improvement, in particular to a coated slow-release fertilizer and application thereof in preventing and controlling absorption of heavy metal cadmium and reducing loss of nitrogen.

Background

The soil is the material foundation for human life and is an important resource for agricultural production development. With the rapid development of social economy, the traditional industrial and agricultural production mode releases heavy metal pollutants into the soil environment, so that the farmland soil is polluted by the heavy metals. The vegetables are important components in the dietary structure of China, are also easily polluted by heavy metals, and have higher enrichment degree on the heavy metals.

The vegetable growth cycle is short, the yield is large, the fertilizer application amount is high, and the fertilizer application times are also high, so the nutrient content of vegetable soil, especially the NO of soil₃ ^-The content of-N is higher. In addition, because vegetables have characteristics such as shallow root systems and favoring fertilizer water, in actual production, chemical fertilizers and organic fertilizers are used in large quantities, and the quantity exceeds the actual demand of the vegetables by multiple times, so that the loss of nitrogen in soil is serious. Therefore, the heavy metal restoration and the nitrogen loss control in the vegetable field soil are organically combined, and scientific and effective biological and agricultural measures are taken to effectively reduce the farmland pollution and the heavy metal content of agricultural products.

Chinese patent document CN104046361A discloses a compound heavy metal contaminated soil conditioner, which comprises the following components: the fertilizer comprises plant ash, calcium magnesium phosphate fertilizer, quicklime, zeolite and organic fertilizer, wherein the weight ratio of the plant ash is as follows: calcium magnesium phosphate fertilizer: quick lime: zeolite: organic fertilizer (0.3-1.1): (0.1-1.2):(0.4-2.1): (0.1-0.6): (0.008-0.06): (0.4-1.2). The soil conditioner fixes heavy metals in polluted soil by inorganic components such as quicklime, calcium magnesium phosphate, phosphate in hydroxyapatite, potassium carbonate in plant ash and the like, so that the activity of the heavy metals is reduced, however, after the soil conditioner is applied to cadmium-polluted soil, the remediation effect is not ideal, the cadmium content in crops is still high, and the soil conditioner needs to be applied in a large amount at one time, generally 2250-4500kg/hm²The transportation cost and the application cost are both high, and the fertilizer is not easy to be accepted by farmers and difficult to be popularized in a large area.

Disclosure of Invention

The invention aims to provide a coated slow-release fertilizer and application thereof in preventing and controlling heavy metal cadmium absorption and reducing nitrogen loss so as to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a coated slow-release fertilizer, wherein the coating is a sulfur coating, a phosphorus coating or a mineral powder coating.

Further, the mineral powder in the mineral powder coating is attapulgite mineral powder.

The invention also provides application of the coated slow release fertilizer in inhibiting absorption of heavy metal cadmium and reducing loss of nitrogen.

The invention discloses the following technical effects:

after the coated slow-release fertilizer is applied to cadmium-polluted soil, the repairing effect is ideal, the cadmium content in crops is obviously reduced, and the application amount at one time is small, generally 10-50kg/hm²The transportation cost and the application cost can be obviously reduced, and the method is suitable for large-area popularization.

The slow release fertilizer is applied once in the early stage of the production, so that the labor expenditure can be saved. Meanwhile, the fertilizer is concentrated in the early stage, so that the fertilizer in the later stage is reduced, the utilization efficiency of the fertilizer is improved, and the nitrogen loss is reduced.

The slow release fertilizer firstly slowly releases nutrition, and on one hand, the slow release fertilizer is used for improving the photosynthetic rate of crops and providing the growth of vegetables. PO released by slow release fertilizer₄ ^3-The soil stabilizer has a certain absorption effect on heavy metal ions, and can effectively reduce the content of heavy metals in soil. The potassium ions are the most main cations on the surface of the slow release fertilizer and may be subjected to ion exchange with heavy metal ions in soil, so that the heavy metal reacts with functional groups on the surface of the high-molecular slow release fertilizer to form precipitates and the like.

The sulfur-coated slow-release fertilizer is a slow-release fertilizer prepared by coating sulfur and a polymeric wax sealant outside urea, and the sulfur cover film and the coating outside the sulfur cover film have no drug damage to crops and can be slowly decomposed and digested by microorganisms in soil, so that soil acidification cannot be caused. The sulfur-coated slow release fertilizer can reduce the content of heavy metals in an effective state in soil, which is mainly attributed to that on one hand, sulfur in the soil can influence the effectiveness and the plant absorption accumulation amount of the heavy metals in a mode of directly oxidizing, reducing or indirectly releasing metal ligands; on the other hand, sulfur-containing functional groups in the soil are the main factors affecting the activity of heavy metals, and they are capable of forming highly compatible and stable compounds with heavy metals.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the present invention, which should not be construed as limiting the invention but rather as providing a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which they pertain. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The invention provides a coated slow-release fertilizer, wherein the coating is a sulfur coating, a phosphorus coating or a mineral powder coating. The slow release fertilizer can be any fertilizer so as to meet the growth requirement of crops.

In the embodiment of the invention, the fertilizer for coating the slow-release fertilizer is urea, and the mass ratio of the coating to the fertilizer is 3: 7.

In the embodiment of the invention, in the coated slow release fertilizer, the sulfur coating is sulfur, and the phosphorus coating is ground phosphate rock. The coating method can adopt high-temperature melting or adhesive. In the examples of the present invention, the sulfur coating, the phosphorous coating, and the mineral powder coating were applied with the same coating quality.

The mineral powder in the mineral powder coating is attapulgite mineral powder.

The Attapulgite mineral powder refers to Attapulgite (Attapulgite) powder. Attapulgite is a crystalline hydrated magnesium aluminum silicate mineral, has unique layer chain structure characteristic, and has lattice displacement in its structure, and the crystal contains variable amount of Na⁺、Ca²⁺、Fe³⁺、Al³⁺The crystals are needle-shaped, fibrous or fibrous aggregates. The attapulgite has unique dispersion, high temperature resistance, good colloid properties of salt and alkali resistance and the like, higher adsorption decoloring capacity, certain plasticity and binding power, and an ideal chemical molecular formula of the attapulgite is as follows: mg (magnesium)₅Si₈O₂₀(OH)₂(OH₂)₄·4H₂And O. Having an intermediate structure between the chain-like structure and the layered structure. The attapulgite is produced in sedimentary rock and weathering crust in the form of soil and compact blocks, and has white, off-white, grey green or weak sericin luster. The soil is fine and smooth, has a greasy feeling, is light and crisp, has shell-shaped or ragged fracture and strong water absorption. Has viscosity and plasticity when wet, shrinks less after drying, does not show cracks greatly, and is soaked in water to be disintegrated.

The invention also provides application of the coated slow release fertilizer in inhibiting absorption of heavy metal cadmium and reducing loss of nitrogen.

When the coated slow-release fertilizer is applied to cadmium-polluted soil and nitrogen-lost soil, the application amount is 10-50kg/hm²Or increased or reduced application according to soil conditions.

And (3) testing:

the test of the invention has four positions in totalAnd (6) processing. The test cell is rectangular, 3.65m long and 2.65m wide. Respectively applying a sulfur-coated slow-release fertilizer, a phosphorus-coated slow-release fertilizer and a mineral powder-coated slow-release fertilizer in each cell, wherein the application ratios are respectively 4.8g, 5.3g and 5.4g, the finally applied nitrogen contents are the same, and respectively recording the sulfur-coated slow-release fertilizer, the phosphorus-coated slow-release fertilizer and the mineral powder-coated slow-release fertilizer as sulfur-coated slow-release fertilizer, phosphorus-coated slow-release fertilizer and mineral powder-coated slow-release fertilizer. And regulating the fertilizing amount N + P of each treatment by taking conventional fertilization as a reference₂O₅+K₂O＝225kg：225kg：225kg/hm². During the period from 2018 to 2019, the yield of vegetables, the total cadmium content in soil, the total cadmium content in vegetables and the nitrogen content in underground permeated water are analyzed based on three-crop vegetable tests of flowering Chinese cabbage, lettuce and cabbage.

The basic properties of the test materials of the present invention, soil and coated slow release fertilizers, are shown in table 1.

TABLE 1

And (3) test results:

1. the yields of the three vegetables are shown in table 2.

TABLE 2

2. Total cadmium concentration in soil:

after three-crop cultivation, the total cadmium content in the contrast soil is 2.67mg/kg, the total cadmium content in the sulfur-coated soil is 2.35mg/kg, the total cadmium content in the phosphorus-coated soil is 2.60mg/kg, and the total cadmium content in the ore powder-coated soil is 2.56 mg/kg. The total cadmium content in the soil was reduced relative to the control.

The total cadmium content in the initial soil is between 2.50 and 2.75 mg/kg. The total cadmium content in the soil changes along with the input of the coated slow release fertilizer in the soil and the absorption of the green vegetables, and the total cadmium content in the soil sample collected at the end of the test is between 2.35 and 2.76 mg/kg. As an average, the total cadmium content in the control sample was 2.67 mg/kg. Compared with the control, the total cadmium content in the soil treated by the method is reduced, wherein the total cadmium content in the soil treated by the sulfur coating and the ore powder coating is reduced by 11.9 percent and 4.1 percent.

Total cadmium content in vegetable plants:

the total cadmium content in the plants of the flowering Chinese cabbage, the lettuce and the cabbage is between 0.3 and 0.5mg/kg fresh weight, 0.6 and 1.2 mg/kg fresh weight and 0.1 and 0.2mg/kg fresh weight respectively. The lettuce has higher total cadmium content and the cabbage has lower total cadmium content, which is probably caused by lower biomass of the lettuce and higher biomass of the cabbage. Compared with different treatments, the total cadmium content of the sulfur-coated treatment is lower during the cultivation period of the flowering Chinese cabbage, and is reduced by 12.2 percent compared with the control; during the lettuce cultivation period, the total cadmium content of the sulfur coating treatment is reduced by 9.8 percent relative to the control; during cabbage cultivation, the total cadmium content of the sulfur-coated treatment was reduced by 11.6% relative to the control.

3. The water leakage is taken 2 times in each vegetable cultivation period. And collecting a seepage water sample through a water taking pipe embedded in soil by 30cm at each time. Firstly, the amount of leaked water is counted, and then the soluble total nitrogen (DN) and NO in the collected sample are measured₃ ^-And (4) content.

DN and NO in the percolating Water₃ ^-The total loss is calculated as follows:

in the formula: p is DN and NO₃ ^-Total loss in kg/hm²(ii) a Ci is DN and NO in ith leakage water₃ ^-Concentration, in mg/L: vi is the volume of the ith leakage water and the unit is L/hm²。

DN and NO in the leaked water after three-crop vegetable cultivation₃ ^-The contents are shown in Table 3. Because the three coating treatments inherently contain higher DN and NO₃ ^-Thus it causes DN and NO in the soil₃ ^-The loss is high. Deducting the conventional fertilization itselfResulting DN and NO₃ ^-The nitrogen loss ratio in the sulfur coating treatment, the phosphorus coating treatment and the ore powder coating treatment was lower than that in the sulfur coating treatment as shown in table 4, for example.

TABLE 3

TABLE 4

In conclusion, the result of the heavy metal cadmium and nitrogen loss cooperative control experiment shows that the sulfur-coated slow-release fertilizer can effectively reduce the cadmium content in soil and obviously reduce the nitrogen loss.

The above-mentioned embodiments are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.