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CN-121986618-A - Organic-mineral bonding oriented carbon fixation-based long-acting fertilizer preparation method for saline-alkali soil

CN121986618ACN 121986618 ACN121986618 ACN 121986618ACN-121986618-A

Abstract

The invention relates to the technical field of soil improvement and carbon fixation, and particularly discloses a method for long-acting fertilizer preparation of saline-alkali soil based on organic-mineral bonding directional carbon fixation, which comprises the following steps of S1, iron tailing modification, namely, adding iron tailings into a low-molecular organic acid solution with the concentration of 0.5-1.0 mol/L, controlling the solid-liquid ratio to be 1:5-1:10, stirring for 2-4 hours at normal temperature, washing to be neutral after modification, drying at 60-80 ℃, crushing and sieving with a 200-mesh sieve to obtain an active carrier with the gamma-FeOOH crystal form accounting for more than or equal to 90%, wherein the surface hydroxyl density of the active carrier is more than or equal to 5.8 sites/nm < 2 >, S2.1, organic carbon source treatment, humic acid preparation, and crushing to 80-100 meshes, wherein the raw materials with the carboxyl content of more than or equal to 3.2 mmol/g and the elemental composition C/H/O of more than or equal to 58/35% are selected. The method for long-acting fertilizer preparation of the saline-alkali soil based on organic-mineral bonding directional carbon fixation can reduce the conductivity of a cultivated layer and prolong the recurrence period of secondary salinization.

Inventors

  • LI YUYI
  • Wei Heya
  • ZHANG HONGYUAN
  • YU RU
  • FENG WENHAO
  • CHEN MENGMENG
  • LI XIAOBIN
  • WANG JING
  • ZHANG MENGXUAN
  • Li Haoruo

Assignees

  • 中国农业科学院农业资源与农业区划研究所
  • 盐碱地综合利用技术创新中心

Dates

Publication Date
20260508
Application Date
20260119

Claims (8)

  1. 1. The method for long-acting fertilizer application of the saline-alkali soil based on organic-mineral bonding directional carbon fixation is characterized by comprising the following steps of: S1, modifying the iron tailings, namely treating the iron tailings by using 0.5-1.0 mol/L low-molecular organic acid solution to prepare a gamma-FeOOH carrier with the surface hydroxyl density of more than or equal to 5.8 sites/nm 2; S2, mixing materials: Premixing humic acid with carboxyl content more than or equal to 3.2 mmol/g, crop straw scraps with C/N ratio of 40-60:1 and livestock manure with decomposition degree more than or equal to 80% according to weight ratio of 1 (1.5-2.5) (1.0-1.5); Spraying nano montmorillonite suspension with the layer charge of 0.5-0.7 eq/mol on the surface of the organic carbon source mixture for wetting; uniformly mixing a wet organic carbon source with 100 parts by weight of modified iron tailings and 15-25 parts by weight of desulfurized gypsum to obtain an improved fertilizer; S3, preparing an organic-mineral composite modifier, namely mixing an organic material rich in aromatic structures and oxygen-containing functional groups, a mineral matrix and a bonding accelerator, and carrying out composting fermentation, wherein the stacking height is less than or equal to 1.0 meter, so as to obtain the organic-mineral composite modifier; S4, field implementation, namely spreading the modified fertilizer at the application amount of 1500-2500 kg/mu, spreading the organic-mineral composite modifier at the application amount of 200-500 kg/mu, and immediately deep ploughing and burying for 20-30 cm.
  2. 2. The method for long-acting fertilizer preparation of saline-alkali soil based on organic-mineral bonding directional carbon fixation, which is characterized in that the gamma-FeOOH carrier is obtained by modifying citric acid or oxalic acid, and the gamma-FeOOH crystal form accounts for more than or equal to 90%.
  3. 3. The method for long-acting fertilization of saline-alkali soil based on organic-mineral bonding directional carbon fixation of claim 1, wherein the crop straw scraps are corn or rice straw with the length of 2-5 cm.
  4. 4. The method for long-acting fertilizer preparation of saline-alkali soil based on organic-mineral bonding directional carbon fixation, which is characterized in that the concentration of the nano montmorillonite suspension is 10+/-1 g/L, and the spraying amount is 5-10 parts of dry montmorillonite for every 100 parts of modified iron tailings.
  5. 5. The method for long-acting fertilizer placement of saline-alkali soil based on organic-mineral bonding directional carbon fixation according to claim 1, wherein deep ploughing is carried out under the condition that the water content of soil is 15-25%, and the interval between broadcasting and deep ploughing is less than or equal to 2 hours.
  6. 6. The method for long-acting fertilizer for saline-alkali soil based on organic-mineral bonding directional carbon fixation according to claim 1, wherein the particle size of the desulfurized gypsum is 0.1-0.5 mm, The content is more than or equal to 95 percent.
  7. 7. The method for long-acting fertilization of saline-alkali soil based on organic-mineral bonding directional carbon fixation according to claim 1, wherein the step S2 is carried out by adopting a double-shaft stirrer in a mixing way, and the rotating speed is 30-45 rpm.
  8. 8. The method for long-acting fertilization of saline-alkali soil based on organic-mineral bonding directional carbon fixation according to claim 1, wherein the application time is 3-4 months in spring or 9-10 months in autumn.

Description

Organic-mineral bonding oriented carbon fixation-based long-acting fertilizer preparation method for saline-alkali soil Technical Field The invention relates to the technical field of soil improvement and carbon fixation intersection, in particular to a method for long-acting fertilizer application of saline-alkali soil based on organic-mineral bonding directional carbon fixation. Background The traditional saline-alkali soil improvement technology faces three major bottlenecks, namely, firstly, poor stability of an organic carbon warehouse, acceleration of mineralization of microorganisms caused by saline-alkali stress when organic materials are applied, high annual mineralization loss rate of the organic carbon reaches 30-70%, the carbon turnover period is generally shorter than 2 years, effective carbon sink is difficult to form, secondly, the secondary salinization recurrence rate is high, the annual application amount of chemical modifiers such as desulfurization gypsum is more than or equal to 3 tons/mu, the salt inhibition effect only maintains 1-2 growth seasons, thirdly, nutrient retaining capacity is weak, and the Cation Exchange Capacity (CEC) of the saline-alkali soil is always lower than 10 cmol/kg, so that the leaching loss rate of nitrogen and phosphorus nutrients exceeds that of a conventional farmland by more than 25%. In the prior art, although the organic matters can be lifted in a short period by simply adding the organic fertilizer, a mineral protection mechanism is omitted, the mineral combination proportion of the added carbon is less than 15%, and the physical isolation method prolongs the carbon retention time, but has limited salt inhibition effect and high operation cost. In recent years, research reveals that the iron oxide-organic matter coprecipitation can enhance the carbon stability (Nature Geoscience, 2020), but the direct application faces the key obstacle that the density of the surface hydroxyl groups of the natural iron oxide is more lower than 4.2 sites/nm2, the complexation efficiency of the natural iron oxide and humic acid carboxyl groups is less than 35%, and the carbon rate of mineral coating is only 18.6+/-5.1% due to the limited contact interface of a randomly mixed organic-mineral system. Therefore, development of a technology based on a directional bonding mechanism is needed, and long-acting fixation and barrier factor cooperative treatment of a carbon pool in the saline-alkali soil are synchronously realized through precisely regulating and controlling the characteristics of a mineral carrier, the matching of organic matter functional groups and the space contact efficiency. Disclosure of Invention In order to solve the technical problems, the invention is realized by the following technical scheme that the method for long-acting fertilizer preparation of the saline-alkali soil based on organic-mineral bonding directional carbon fixation comprises the following steps: S1, iron tailings are modified, namely the iron tailings are put into a low molecular organic acid solution with the concentration of 0.5-1.0 mol/L, the solid-liquid ratio is controlled to be 1:5-1:10, and the mixture is stirred for 2-4 hours at normal temperature; Washing the modified active carrier with water to be neutral, drying at 60-80 ℃, crushing, and sieving with a 200-mesh sieve to obtain an active carrier with the gamma-FeOOH crystal form accounting for more than or equal to 90%, wherein the density of surface hydroxyl groups is more than or equal to 5.8 sites/nm2; S2, preparing a functional material: S2.1, organic carbon source treatment: Selecting raw materials with carboxyl content more than or equal to 3.2 mmol/g and element composition C/H/O more than or equal to 58/4/35%, crushing to 80-100 meshes, selecting corn or rice straw with C/N ratio of 40-60:1, mechanically crushing to 2-5 cm, selecting cow dung or sheep dung with decomposition degree more than or equal to 80% and water content less than or equal to 30%, and crushing to 10-20 meshes; Premixing humic acid, straw scraps and manure in a proportion of 1 (1.5-2.5) to 1.0-1.5 to form an organic carbon source mixture; s2.2, mineral component treatment, namely grinding the desulfurized gypsum to the particle size of 0.1-0.5 mm, wherein The content is more than or equal to 95 percent; S2.3, preparing an auxiliary agent, namely preparing nano montmorillonite with the layer charge of 0.5-0.7 eq/mol into 10+/-1 g/L suspension, and performing ultrasonic dispersion for 20 minutes; s2.4 directed complex construction: Uniformly spraying 5-10 parts (calculated by dry montmorillonite) of nano montmorillonite suspension on the surface of 30-50 parts of organic carbon source mixture, slightly stirring and wetting, putting the wetted organic carbon source mixture, 100 parts of modified iron tailings and 15-25 parts of desulfurized gypsum powder into a double-shaft stirrer, and mixing for 10 minutes at the rotating speed of 30-45 rpm to form