A method for improving saline-alkali soil

Abstract

The application discloses a saline-alkali soil improvement method and belongs to the technical field of saline-alkali soil improvement. The method comprises the following steps: in a screw extruder, humic acid and acrylic acid are grafted and polymerized in a reaction section to form humic acid grafted acrylic acid polymer; N-[2-(2-methoxy-5-nitro-phenoxy)ethyl]pyridine, [2-(3,4-dichlorophenoxy)-ethyl]hexadecyl diethyl ammonium bromide and furfural residue are sequentially added at the opening of a conveying section, and after passing through a mixing section, the mixture is extruded and granulated to obtain a conditioner; according to weight parts, the furfural residue is 70-90 parts, the humic acid grafted acrylic acid polymer is 10-25 parts, and the N-[2-(2-methoxy-5-nitro-phenoxy)ethyl]pyridine and [2-(3,4-dichlorophenoxy)-ethyl]hexadecyl diethyl ammonium bromide are 1-5 parts. The conditioner is applied to saline-alkali soil by being scattered in the soil during ploughing or being applied to the soil by hole planting during sowing, so that the organic matter content of the soil can be increased, the saline-alkali components can be separated from the roots of crops, the stress of the saline-alkali soil on the crops can be effectively reduced, and the yield of the crops can be improved.

Description

Technical Field

[0001] This invention relates to the field of soil improvement technology, and specifically to a method for improving saline-alkali soil. Background Technology

[0002] Soil salinization is a widespread problem worldwide. In my country, saline-alkali land is distributed across 17 provinces, including the Northwest, North China, Northeast, and coastal areas, with a total area of ​​over 1.5 billion mu (approximately 100 million hectares) and showing a continuous expansion trend, seriously affecting my country's agricultural production level.

[0003] In recent years, researchers at home and abroad have conducted a large number of experiments on the improvement of saline-alkali soil. Existing improvement methods include physical improvement technology, chemical improvement technology, biological improvement technology, and water conservancy engineering improvement technology, but most of these technologies are costly and difficult to promote and apply on a large scale.

[0004] my country is the world's largest producer of furfural, generating a large amount of acidic furfural residue every year that is difficult to treat. It has a high organic matter content and contains macro- and micro-elements such as nitrogen, phosphorus, and potassium needed by crops. Therefore, it is used as a soil conditioner for saline-alkali soil. However, its usage is relatively large, usually ranging from hundreds of kilograms to tens of tons per mu. Excessive use may have adverse effects on soil and ecological environment. [Cui Xiangchao et al., Effects of papermaking powder and furfural residue on maize growth and soil microbial properties in coastal saline-alkali land, Journal of Ecology and Rural Environment, 2014, 30(3): 331-335; Fan Liqin et al., Research progress on the application of industrial waste in saline-alkali land improvement, Henan Agricultural Sciences, 2012, 41(1): 21-24].

[0005] With the widespread application of water-saving irrigation technologies such as drip irrigation (especially drip irrigation under mulch) in arid regions such as Xinjiang, new requirements have been put forward for the management of saline-alkali land under water-saving irrigation conditions [Hu Mingfang, Tian Changyan, Zhao Zhenyong, Wang Linxia. Research progress on the causes and improvement measures of saline-alkali land in Xinjiang, Journal of Northwest A&F University (Natural Science Edition), 2012, 40(10): 111-117]. It is necessary to develop a soil conditioner that is suitable for water-saving irrigation operations such as drip irrigation, with low dosage, good effect, low cost, and simple operation, and meets the needs of comprehensive management of large areas of saline-alkali land in arid and water-scarce areas. Summary of the Invention

[0006] Based on the current state of technology, the purpose of this invention is to provide a method for treating saline-alkali land, which can quickly and effectively reduce the salinity and alkali content of the topsoil.

[0007] To achieve the objectives of this invention, the specific technical solution is as follows:

[0008] The method for improving saline-alkali soil includes the following steps: In a screw extruder, humic acid and acrylic acid are grafted and polymerized in a reaction section to form a humic acid-grafted acrylic acid polymer; N-[2-(2-methoxy-5-nitro-phenoxy)ethyl]pyridine chloride, [2-(3,4-dichlorophenoxy)-ethyl]hexadecyl diethylammonium bromide, and furfural residue are added sequentially at the opening of the conveying section. After passing through a mixing section, the mixture is extruded and granulated to obtain a conditioner. By weight, the conditioner contains 70-90 parts furfural residue, 10-25 parts humic acid-grafted acrylic acid polymer, and 1-5 parts N-[2-(2-methoxy-5-nitro-phenoxy)ethyl]pyridine chloride and [2-(3,4-dichlorophenoxy)-ethyl]hexadecyl diethylammonium bromide. The conditioner is applied to the saline-alkali soil by spreading it during tillage or by sowing in holes during seeding.

[0009] The humic acid is one or more of fulvic acid and its salts, biochemical humic acid and its salts, preferably potassium fulvicate;

[0010] The furfural residue has a moisture content of 30-50% and a pH of 2.0-4.0.

[0011] The conditioner is applied during tillage or sown into saline-alkali soil at a rate of 5-10 kg / mu.

[0012] The conditioning agent is prepared by the following method: humic acid is fed into the extruder through the main feed port; acrylic acid and initiator solution are pumped in through the opening above the screw mixing section; after passing through the mixing section and reaction section at 80-130℃, a humic acid-grafted acrylic acid polymer is formed; N-[2-(2-methoxy-5-nitro-phenoxy)ethyl]pyridine chloride, [2-(3,4-dichlorophenoxy)-ethyl]hexadecyldiethylammonium bromide, and furfural residue are added sequentially at the opening of the conveying section; after passing through the mixing section, the mixture is extruded and cut into 0.5-3cm particles at the die head to obtain the conditioning agent. The initiator is one or both of cerium ammonium nitrate and persulfate, preferably cerium ammonium nitrate and potassium persulfate.

[0013] The beneficial effects of adopting the above technical solution are as follows: the preparation of saline-alkali soil conditioner by reactive extrusion can be carried out continuously without generating wastewater pollution and with low process cost; furfural residue reduces soil pH through neutralization and plays a slow-release role, continuously releasing humic acid grafted acrylic polymer and surfactants during the crop growth period with irrigation, thus achieving the purpose of long-term salinity reduction. Detailed Implementation

[0014] To better illustrate the present invention, the following embodiments are provided:

[0015] Example 1

[0016] The parallel twin-screw extruder has a screw length-to-diameter ratio of 58. The temperatures for each zone are set as follows: Zone 1 80℃, Zone 2 135℃, Zone 3 140℃, Zone 4 145℃, Zone 5 145℃, Zone 6 145℃, and the die head 140℃. The screw speed is 30 rpm. 5 kg of biochemical humic acid and 5 kg of acrylic acid neutralized to a pH of 6.0-6.5 with potassium hydroxide are mixed evenly in a high-speed mixer. The uniformly mixed material is fed through a hopper. Then, aqueous solutions containing 0.3 kg of 20% potassium persulfate and 0.4 kg of 30% cerium ammonium nitrate are quantitatively injected into the screw via a dynamic mixer for material transport and polymerization initiation. Add 0.5 kg of N-[2-(2-methoxy-5-nitro-phenoxy)ethyl] pyridine chloride, 0.5 kg of [2-(3,4-dichlorophenoxy)-ethyl] hexadecyl diethyl ammonium bromide, and 89 kg of furfural residue sequentially to the opening of zone six. After mixing, extrude the mixture and cut it into 0.5 cm particles at the die head to obtain conditioner 1.

[0017] Example 2

[0018] The parallel twin-screw extruder has a screw length-to-diameter ratio of 58. The temperatures for each zone are set as follows: Zone 1 80℃, Zone 2 135℃, Zone 3 140℃, Zone 4 145℃, Zone 5 145℃, Zone 6 145℃, and the die head 140℃. The screw speed is 30 rpm. 10 kg of fulvic acid and 5 kg of acrylic acid neutralized to a pH of 6.0-6.5 with potassium hydroxide are mixed evenly in a high-speed mixer. The uniformly mixed material is fed through a hopper. Then, aqueous solutions containing 0.4 kg of 20% potassium persulfate and 0.5 kg of 30% cerium ammonium nitrate are quantitatively injected into the screw via a dynamic mixer for material transport and polymerization initiation. 1 kg of N-[2-(2-methoxy-5-nitro-phenoxy)ethyl] pyridine chloride, 1 kg of [2-(3,4-dichlorophenoxy)-ethyl] hexadecyl diethyl ammonium bromide and 83 kg of furfural residue were added sequentially at the opening of the sixth zone. After passing through the mixing section, the mixture was extruded and cut into 1 cm particles at the die head to obtain conditioner 2.

[0019] Example 3

[0020] The parallel twin-screw extruder has a screw length-to-diameter ratio of 58. The temperatures for each zone are set as follows: Zone 1 80℃, Zone 2 135℃, Zone 3 140℃, Zone 4 145℃, Zone 5 145℃, Zone 6 145℃, and the die head 140℃. The screw speed is 30 rpm. 10 kg of fulvic acid and 10 kg of acrylic acid are mixed evenly in a high-speed mixer. The uniformly mixed material is fed through a hopper. Then, aqueous solutions containing 0.6 kg of 20% potassium persulfate and 0.6 kg of 30% cerium ammonium nitrate are quantitatively injected into the screw via a dynamic mixer for material conveying and polymerization initiation. 1 kg of N-[2-(2-methoxy-5-nitro-phenoxy)ethyl] pyridine chloride, 2 kg of [2-(3,4-dichlorophenoxy)-ethyl] hexadecyl diethyl ammonium bromide and 77 kg of furfural residue were added sequentially at the opening of the sixth zone. After passing through the mixing section, the mixture was extruded and cut into 2 cm particles at the die head to obtain conditioner 3.

[0021] Example 4

[0022] The parallel twin-screw extruder has a screw length-to-diameter ratio of 58. The temperatures for each zone are set as follows: Zone 1 80℃, Zone 2 135℃, Zone 3 140℃, Zone 4 145℃, Zone 5 145℃, Zone 6 145℃, and the die head 140℃. The screw speed is 30 rpm. 10 kg of fulvic acid and 15 kg of acrylic acid are mixed evenly in a high-speed mixer. The uniformly mixed material is fed through a hopper. Then, aqueous solutions containing 0.8 kg of 20% potassium persulfate and 0.4 kg of 30% cerium ammonium nitrate are quantitatively injected into the screw via a dynamic mixer for material transport and polymerization initiation. 1 kg of N-[2-(2-methoxy-5-nitro-phenoxy)ethyl] pyridine chloride, 4 kg of [2-(3,4-dichlorophenoxy)-ethyl] hexadecyl diethyl ammonium bromide and 70 kg of furfural residue were added sequentially at the opening of zone 6. After passing through the mixing section, the mixture was extruded and cut into 3 cm particles at the die head to obtain conditioner 4.

[0023] Example 5: Field Trial

[0024] Location: Fengheyuan Farm, Heshilik Township, Korla City, Xinjiang. The experimental field of 4 mu was divided into 4 equal parts, and the control field of 1 mu was used.

[0025] Before the experiment, soil samples from 0-30 cm depth were analyzed. The results showed that the total salt content was 1.58%, the pH was 8.8, and the organic matter content was 11.2 g / kg.

[0026] Experimental methods: (1) The saline-alkali experimental field and the control field were plowed in the same way. Conditioner 1-4 prepared in the present invention was applied to experimental fields 1-4 respectively, while no conditioner was applied to the control field. (2) Cotton was sown in both experimental and control fields, and drip irrigation tape, fertilizer tank and mulch were installed at the same time. (3) Fertilization and field management were carried out in the same way as conventional methods in both experimental and control fields. Seven days after the third drip irrigation, soil samples from 0-30 cm were taken for analysis; at the same time, 10 cotton plants were randomly selected from each treatment, and the chlorophyll content of the fourth leaf from the bottom 1 cm away from the edge was measured using a SPAD-502Plus chlorophyll meter, and the average value was taken. After the cotton matured, the yield was measured according to DB37-T4503-2022. The experimental results are shown in Table 1.

[0027] Table 1. Soil and cotton indices in the control and treatment groups

[0028]

[0029] Experimental results show that after applying the saline-alkali soil conditioner, the total salt content and pH of the soil decreased significantly, while the soil organic matter content increased. The chlorophyll content indicates that the cotton growth in treatment groups 1-4 was better than that in the control group, with the highest yield increase being 14.87%. This demonstrates that the saline-alkali soil conditioner prepared in this invention has significant effects and has great potential for widespread application.

[0030] Example 5: Synthesis of [2-(3,4-dichlorophenoxy)-ethyl]hexadecyldiethylammonium bromide

[0031] 524 g of [2-(3,4-dichlorophenoxy)-ethyl]diethylamine and 650 g of 1-bromohexadecane were added to 2 L of ethyl acetate solution, heated under reflux for 8 hours, cooled, and then petroleum ether was added and stirred. The solid was filtered off, washed with petroleum ether, and dried under vacuum to obtain 1032 g of the product [2-(3,4-dichlorophenoxy)-ethyl]dodecyldiethylammonium bromide, with a yield of 91%.

[0032] 1 HNMR (400MHz, CDCl3) δ7.37(d,J=8.8Hz,1H),7.07(d,J=3.2Hz,1H),6.91(dd,J1=8.8Hz,J2=3.2Hz,1H),4.59(t,J=4.2Hz,2H),4.18(t,J =4.6Hz,2H),3.66-3.61(m,4H),3.41-3.37(m,2H),1.78-1.65(m,4H),1.48(t,J=7.2Hz,6H),1.37-1.26(m,24H),0.88(t,J=6.8Hz,3H);

[0033] 13C NMR (100MHz, CDCl3) δ156.0,133.0,130.9,125.3,116.8,114.3,62.7,59.2,57.3,54 .9,31.8,29.6,29.5,29.5,29.5,29.4,29.3,29.2,29.1,26.4,22.6,22.2,14.0,8.3.

[0034] The above description is merely an example of the embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving saline soil, characterized by, The conditioner prepared by the following method is applied to saline-alkali land during tillage or by sowing in holes during sowing, at a rate of 5-10 kg / mu. The conditioning agent is prepared by the following method: humic acid is fed into a parallel twin-screw extruder through the main feed port; acrylic acid and initiator solution are pumped in through the opening above the mixing section of the screw; after passing through the mixing section and reaction section at 80-130°C, a humic acid-grafted acrylic acid polymer is formed; N-[2-(2-methoxy-5-nitro-phenoxy)ethyl]pyridine chloride, [2-(3,4-dichlorophenoxy)-ethyl]hexadecyl diethylammonium bromide, and furfural residue are added sequentially at the opening of the conveying section; after passing through the mixing section, the mixture is extruded and cut into 0.5-3 cm particles at the die head to obtain the conditioning agent; the initiator is one or both of cerium ammonium nitrate or persulfate. By weight, it contains 70-90 parts furfural residue, 10-25 parts humic acid grafted acrylic polymer, and 1-5 parts N-[2-(2-methoxy-5-nitro-phenoxy)ethyl] pyridine chloride and [2-(3,4-dichlorophenoxy)-ethyl] hexadecyl diethyl ammonium bromide; The humic acid mentioned is one or more of fulvic acid and its salts, biochemical humic acid and its salts; The furfural residue has a moisture content of 30-50% and a pH of 2.0-4.0.

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