A woody peat humic acid iron complex fertilizer, a preparation method thereof and application thereof in improving farmland soil

Abstract

The present application provides a kind of woody peat humic acid iron complex fertilizer and its preparation method and application in improving cultivated soil, belong to fertilizer technical field.The woody peat humic acid iron complex fertilizer provided in the present application has organic matter content of 47.4wt% or more, mainly is difficult to decompose organic matter component, has the effect of quickly improving the organic matter content of cultivated soil, especially the content of difficult to decompose organic matter;Woody peat humic acid iron complex fertilizer can quickly aggregate soil particles after being applied to soil, effectively enhance the stability of soil structure;Woody peat humic acid iron complex fertilizer is rich in nitrogen, phosphorus, potassium, sulfur nutrient elements, can improve soil nitrogen, phosphorus, potassium, sulfur and other nutrients after being applied to soil.The woody peat humic acid iron complex fertilizer provided in the present application can effectively improve the organic matter of cultivated soil, soil structure and soil nutrient status, so as to provide good material and means for cultivated soil improvement.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fertilizers, and particularly relates to a woody peat humic acid iron complex fertilizer, a preparation method thereof and application thereof in improving cultivated land soil. BACKGROUND

[0002] At present, through land consolidation projects, active consolidation, reclamation and development of low-yield cultivated land and reserve cultivated land resources are an important measure to alleviate the rapid decline in the number of cultivated land. However, due to the lack of long-term fertilization and maturation process, the soil quality of these newly consolidated cultivated land is generally poor, and there are prominent problems such as low soil organic matter content, poor soil structure, and nutrient deficiency. In order to improve the soil organic matter and nutrient content of newly consolidated cultivated land and improve its soil structure, people traditionally use straw, organic fertilizer or even only rely on chemical fertilizer to fertilize and mature the soil of such newly consolidated cultivated land. However, since straw and organic fertilizer are easy to decompose, and chemical fertilizer is easy to leach and has a short effective period, traditional fertilization methods generally need 10-20 years to significantly improve the fertility level of newly consolidated cultivated land. Therefore, how to quickly improve the soil organic matter and nutrient content and improve the soil structure is a difficulty in the rapid and efficient use of newly consolidated cultivated land.

[0003] Organic matter is the most important carbon pool, nutrient and energy source in farmland ecosystems, and is also the main cementing material for the formation and stability of good soil structure, which greatly affects the soil's ability to retain and supply fertilizer and its buffering performance, and thus is the most important indicator for measuring the quality and fertility level of cultivated land. For high-quality fertile cultivated land, the proportion of recalcitrant organic matter in soil organic matter usually accounts for 60%-90%. Therefore, one of the keys to quickly fertilizing newly consolidated cultivated land is how to quickly improve its organic matter, especially the content of recalcitrant organic matter. Based on this understanding, in recent years, people have also used recalcitrant biochar and humic acid to fertilize and improve the soil. However, although biochar can quickly increase the content of recalcitrant organic matter in soil, it is mainly in a free state in soil and is difficult to combine with soil clay minerals to form organic-inorganic complexes, thereby making it difficult to effectively improve the soil structure. Although humic acid has better combination ability with soil minerals than biochar, its combination efficiency may not be fully utilized if there is a lack of sufficient bridging ions (such as iron ions, calcium ions, etc.).

[0004] In addition, humic acid is usually an alkali-soluble organic component extracted from peat, coal, organic fertilizer, river and lake sediment, soil, etc. with an alkali solution (such as sodium hydroxide) of a certain concentration. If the alkali-soluble humic acid is to be changed into a solid state that is insoluble, a strong acid solution such as sulfuric acid or hydrochloric acid needs to be added to the alkali-soluble humic acid solution to adjust the pH of the humic acid solution to about 2. At this time, the components that are not dissolved in the acid solution will combine with H +The ion reacts to become solid phase material and mutually aggregates and deposits. This part of solid phase component is called humic acid, and the component still dissolved in the acid solution is called fulvic acid (also called yellow humic acid). As can be seen from the traditional extraction method of humic acid, although the traditional process can obtain solid humic acid, but it cannot simultaneously aggregate and deposit the fulvic acid with the smallest molecular weight, the highest total acidity and activity, the higher cation exchange capacity and complex capacity. This part of active fulvic acid can only be applied to the soil or crops in the form of water-soluble yellow humic acid. However, because the fulvic acid is easily dissolved in water, the fulvic acid is easily leached when applied alone. And the traditional extraction method does not introduce iron, calcium and other bridge ions, and cannot better enhance the binding capacity of humic acid and soil minerals. In addition, the traditional extraction method also needs to use a large amount of sulfuric acid or hydrochloric acid and other regulated hazardous chemicals. SUMMARY

[0005] Therefore, the present application aims to provide a preparation method of a woody peat humic acid iron complex fertilizer, which is simple, can simultaneously complex and aggregate humic acid and fulvic acid, does not use sulfuric acid, hydrochloric acid and other regulated hazardous chemicals, has lower production cost, is easy to mass produce, and has one-time investment and long-term effect.

[0006] The present application also aims to provide an application of the woody peat humic acid iron complex fertilizer in improving the farmland soil.

[0007] The present application also aims to provide a woody peat humic acid iron complex fertilizer, which can quickly and durably increase the soil organic matter, especially the content of refractory organic matter, improve the soil structure condition, and increase the soil nutrient content.

[0008] The present application provides a woody peat humic acid iron complex fertilizer, which is prepared from the following raw materials in a proportion:

[0009] 100g of woody peat, 0.2-0.3mol of sodium hydroxide, 0.15-0.3mol of iron chloride, 5-10g of ammonium sulfate and 2-5g of potassium dihydrogen phosphate.

[0010] Preferably, the woody peat humic acid iron complex fertilizer is prepared from the following raw materials in a proportion: 100g of woody peat, 2-3L of 0.1mol / L sodium hydroxide aqueous solution, 1.5-3L of 0.1mol / L iron chloride aqueous solution, 5-10g of ammonium sulfate and 2-5g of potassium dihydrogen phosphate.

[0011] The present application provides a preparation method of the woody peat humic acid iron complex fertilizer as described in the above scheme, which comprises the following steps:

[0012] Mixing the woody peat with the sodium hydroxide aqueous solution to obtain a crude woody peat humic acid solution;

[0013] Mixing the iron chloride aqueous solution with the crude woody peat humic acid solution, aging to obtain the woody peat humic acid iron.

[0014] After the wood peat humic acid iron is purified by water washing, ammonium sulfate and potassium dihydrogen phosphate are added while stirring to obtain the wood peat humic acid iron complex fertilizer.

[0015] Preferably, the aging time is 24-64 h.

[0016] Preferably, the aging temperature is 15-30 DEG C.

[0017] Preferably, the moisture content of the wood peat is 20%-150%.

[0018] Preferably, the mixing method is preferably that 100 g of the wood peat is mixed with 2 L of 0.1 mol / L sodium hydroxide aqueous solution, after the upper solution is collected, the remaining precipitate is mixed with 1 L of 0.1 mol / L sodium hydroxide aqueous solution, the upper solution is collected, and the two upper solutions are combined to obtain a crude wood peat humic acid solution.

[0019] Preferably, after the aging, the method further comprises collecting the solid phase from the aged system, and water washing and purifying to remove the salt.

[0020] The application also provides the application of the wood peat humic acid iron complex fertilizer or the wood peat humic acid iron complex fertilizer prepared by the preparation method in the improvement of cultivated soil.

[0021] Preferably, the cultivated land includes various types of cultivated land with lower fertility level such as newly improved cultivated land and low-yield land.

[0022] Based on the above technical solution, the wood peat humic acid iron complex fertilizer has the following characteristics and technical advantages:

[0023] 1) In the wood peat humic acid iron preparation method, the extraction process of humic acid has the advantages of lower cost, simpler operation, and simultaneous solidification of humic acid components and active fulvic acid components compared with the traditional extraction process. At the same time, the wood peat humic acid iron preparation method provides a large amount of bridging iron ions, which can effectively enhance the binding capacity of wood peat humic acid and soil minerals, promote soil carbon sequestration and soil structure improvement. In addition, the wood peat humic acid iron preparation method of the application does not need to use regulated hazardous chemicals such as sulfuric acid and hydrochloric acid, and has lower management cost.

[0024] 2) The woody peat humic acid iron complex fertilizer of the present application is rich in recalcitrant humic acid and high-activity ferrihydrite component, the degree of complexation of humic acid with iron (including ferrihydrite) is uniform, and the woody peat humic acid iron complex fertilizer has a small particle size of about 20 nm, has high reactivity, and thus has the ability to rapidly increase the recalcitrant organic matter in the cultivated soil and improve the soil structure. Meanwhile, the woody peat is rich in recalcitrant humic acid, and the humic acid content is 62.0 wt%.

[0025] 3) The woody peat humic acid iron complex fertilizer of the present application can effectively increase the content of organic matter, especially recalcitrant organic matter, in the newly improved cultivated soil, and the improvement efficiency is significantly higher than that of straw, a traditional organic material, and is at the same level as that of biochar and humic acid.

[0026] 4) The woody peat humic acid iron complex fertilizer of the present application also has high contents of nitrogen, phosphorus, potassium, and sulfur nutrient elements, and has the ability to effectively increase the content of nutrient elements in the cultivated soil. The woody peat humic acid iron has a higher effect on the improvement of the C / N ratio of the soil than straw, biochar, and humic acid.

[0027] 5) The woody peat humic acid iron complex fertilizer of the present application can rapidly increase the stability of the soil aggregate structure, and the improvement efficiency is not only much higher than that of the control, but also much higher than that of straw, biochar, and humic acid. The effect of humic acid without a bridging ion on the stability of the soil aggregate structure can only approach that of half the amount of the woody peat humic acid iron complex fertilizer.

[0028] 6) The woody peat humic acid iron complex fertilizer of the present application also has the effect of improving the alkalinity of the calcareous soil and reducing the pH value of the soil, and the influence on the soil salt content is also less than that of organic materials such as straw, biochar, and humic acid. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 NMR spectrum of woody peat humic acid;

[0030] Figure 2 Influence of different volumes of ferric chloride solution on the preparation of woody peat humic acid iron;

[0031] Figure 3 Excess ferric chloride solution detection results during the preparation of woody peat humic acid iron; Note: The left beaker in each group is the supernatant original solution after the first centrifugal separation, and the right beaker is the supernatant after the addition of 10 mL of 0.1 mol / L sodium hydroxide solution;

[0032] Figure 4 X-ray diffraction (XRD) spectrum of the woody peat humic acid iron in Example 3;

[0033] Figure 5 Scanning electron microscope (SEM) results of the woody peat humic acid iron complex fertilizer;

[0034] Figure 6 The result of the spectrum analysis of the wood peat humic acid iron complex fertilizer;

[0035] Figure 7 The result of the detection of the organic carbon content of the improved soil of the different treatment groups;

[0036] Figure 8 The result of the detection of the total nitrogen content of the improved soil of the different treatment groups;

[0037] Figure 9 The result of the detection of the C / N of the improved soil of the different treatment groups;

[0038] Figure 10 The result of the detection of the water stable aggregate of the improved soil of the different treatment groups. DETAILED DESCRIPTION

[0039] The wood peat humic acid iron complex fertilizer is prepared from the following raw materials in a proportion:

[0040] 100g wood peat, 0.2-0.3mol sodium hydroxide, 0.15-0.3mol iron chloride, 5-10g ammonium sulfate and 2-5g potassium dihydrogen phosphate.

[0041] In the present application, the wood peat humic acid iron complex fertilizer is preferably prepared from the following raw materials in a proportion: 100g wood peat, 2-3L 0.1mol / L sodium hydroxide aqueous solution, 1.5-3L 0.1mol / L iron chloride aqueous solution, 5-10g ammonium sulfate and 2-5g potassium dihydrogen phosphate, and more preferably 100g wood peat, 3L 0.1mol / L sodium hydroxide aqueous solution and 2L 0.1mol / L iron chloride aqueous solution, 5-7g ammonium sulfate and 3-4g potassium dihydrogen phosphate.

[0042] The present application provides a preparation method of the wood peat humic acid iron complex fertilizer, which comprises the following steps:

[0043] Mixing wood peat with sodium hydroxide aqueous solution to obtain a crude wood peat humic acid solution;

[0044] Mixing iron chloride aqueous solution with the crude wood peat humic acid solution, aging to obtain wood peat humic acid iron;

[0045] After water washing and purification of the wood peat humic acid iron, adding ammonium sulfate and potassium dihydrogen phosphate while stirring to obtain wood peat humic acid iron complex fertilizer.

[0046] The present application mixes wood peat with sodium hydroxide aqueous solution to obtain a crude wood peat humic acid solution.

[0047] In the present application, the woody peat contains more humic acid than the common organic base, and the content of humic acid is up to 62.0%, which solves the problem of large demand for humic acid and is beneficial to improve the preparation efficiency of woody peat humic acid iron complex fertilizer. The woody peat sample used in the embodiment of the present application is provided by Beijing Zhongxiang Lifeng Technology Co., Ltd. (produced in Indonesia).

[0048] In the present application, the water content of the woody peat is preferably 20% to 150%, more preferably 30 to 140%, further preferably 50% to 120%, and still further preferably 70% to 100%. The experiment of the present application proves that the woody peat with different water contents has an influence on the preparation of woody peat humic acid iron fertilizer. The woody peat after air drying (low water content) has strong hydrophobicity, and the mixing time needs to be lengthened to fully extract humic acid.

[0049] In the present application, the mixing method is preferably mixing 100g of woody peat with 2L of 0.1mol / L sodium hydroxide aqueous solution, collecting the supernatant, and then mixing the remaining precipitate with 1L of 0.1mol / L sodium hydroxide aqueous solution, collecting the supernatant, and combining the two supernatants to obtain a crude woody peat humic acid solution. This method is beneficial to improve the extraction content of humic acid.

[0050] After obtaining the crude woody peat humic acid solution, the present application mixes the aqueous ferric chloride solution and the crude woody peat humic acid solution, and ages to obtain woody peat humic acid iron.

[0051] In the present application, the aqueous ferric chloride solution is preferably added to the crude woody peat humic acid solution, the ferric chloride reacts with sodium hydroxide in the crude woody peat humic acid solution to form nanometer hydro ferrite, the pH of the system is 2.0 to 2.5, the nanometer hydro ferrite and humic acid undergo complexation reaction, and the X-ray diffraction detection results show that the hydro ferrite basically does not undergo crystallization transformation, but successfully complexes with humic acid. Meanwhile, the present application also studies the addition ratio of ferric chloride to crude woody peat humic acid, and the results show that when the volume ratio of the crude woody peat humic acid solution to the aqueous ferric chloride solution is 30:10 or 30:15, the upper layer of the reaction solution is green and blue-green, which is the color of ferrous ions, indicating that the humic acid is excessive, and when the volume ratio is 30:20 or 30:30, the upper layer of the reaction solution is yellow, which is similar to the color of the formed hydro ferrite, indicating that there is residual ferric chloride that has not been completely reacted when the volume ratio is 30:20 or 30:30.

[0052] In the present application, the aging time is preferably 24-64h, more preferably 32-58h, further preferably 35-52h, still further preferably 42-48h, and most preferably 45h. The aging temperature is preferably 10-35℃, more preferably 12-32℃, and most preferably 15-30℃. Meanwhile, the aging time is also optimized in the present application. The results show that the pattern of the aging time (24h or 64h) shows relatively obvious broad peaks near 35° and 62°, which are basically consistent with the diffraction pattern of 2-line ferrihydrite, indicating that the ferrihydrite basically does not undergo crystallization transformation under this condition, and is successfully complexed with humic acid, and is separated immediately after mixing, without realizing complexation.

[0053] In the present application, after aging, the solid phase is collected from the aged system, and the salt is removed. The method for collecting the solid phase is preferably centrifugation. After collecting the precipitate, water washing is used to remove the salt. The water washing is preferably performed until the electrical conductivity is less than 100μs / cm to obtain the woody peat humic acid iron.

[0054] After the woody peat humic acid iron is purified by water washing, it is uniformly mixed with ammonium sulfate and potassium dihydrogen phosphate to obtain a woody peat humic acid iron complex fertilizer.

[0055] The present application provides the application of the woody peat humic acid iron complex fertilizer in improving the soil of cultivated land.

[0056] In the present application, the application method of the woody peat humic acid iron complex fertilizer is preferably as follows:

[0057] 1) The woody peat humic acid iron complex fertilizer as described above is applied to the cultivated land to be improved.

[0058] 2) The applied woody peat humic acid iron complex fertilizer is turned into the plough layer of the cultivated land to be improved.

[0059] Among them, the application method includes mechanical application and manual application.

[0060] Among them, the application amount of the woody peat humic acid iron complex fertilizer is recommended to be between 0.5-3.5 tons per mu.

[0061] Among them, the woody peat humic acid iron complex fertilizer can be applied together with fertilizers, straws, etc. when applied.

[0062] Among them, the cultivated land to be improved includes dry land and paddy field.

[0063] Among them, the thickness of the plough layer of the improved cultivated land is 15-20cm.

[0064] The above merely describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the scope of the present application.

[0065] The wood-based peat humic acid iron complex fertilizer, the preparation method thereof and the application thereof in improving the soil of farmland will be described in detail below in combination with the embodiments, but they should not be understood as limiting the protection scope of the present application.

[0066] Example 1

[0067] Effect of different volumes of sodium hydroxide solution on preparation of wood-based peat humic acid iron

[0068] 100 g of wood-based peat and 2 L of 0.1 mol / L sodium hydroxide aqueous solution were mixed and fully stirred, and the upper solution was collected by centrifugation. 100 g of wood-based peat and 2 L of sodium hydroxide aqueous solution were mixed and fully stirred, and the upper solution was collected by centrifugation. The above two groups of collected crude humic acid solutions were added with 2 L of 0.1 mol / L ferric chloride solution while stirring. After being placed at room temperature for 24 hours, they were centrifuged and washed with water, and the product was obtained after purification to a conductivity of less than 100 μs / cm.

[0069] If the use of sodium hydroxide is reduced or increased, the corresponding ferric chloride solution should also be increased or reduced. However, considering the cost and time of extraction, it is still recommended to extract 3 L of crude humic acid solution twice.

[0070] Example 2

[0071] Effect of different volumes of ferric chloride solution on preparation of wood-based peat humic acid iron

[0072] 100 g of wood-based peat and 2 L of 0.1 mol / L sodium hydroxide solution were mixed and fully stirred, and the upper solution was collected by centrifugation. The residue was added with 1 L of sodium hydroxide solution, and the above steps were repeated, and a total of 3 L of crude humic acid solution was collected. Different volumes of 0.1 mol / L ferric chloride solution were added while stirring, including 1 L, 1.5 L, 2 L, and 3 L, a total of 4 gradients. After being placed at 25°C for 24 hours, they were centrifuged and washed with water, and the product was obtained after purification to a conductivity of less than 100 μs / cm.

[0073] As Figure 2As shown, 30:10, 30:15, 30:20 and 30:30 are volume ratios, respectively corresponding to 1L, 1.5L, 2L, 3L of ferric chloride solution added to 3L of crude humic acid solution. The solution in the beaker is the first supernatant centrifuged out in step 3. Compared with the color of the pure 0.1M ferric chloride solution in the 5th beaker, the colors of the beakers of 30:10, 30:15 and 30:20 are obviously lighter, and the color of the beaker of 30:10 is close to transparent. This indicates that 1L of ferric chloride solution cannot completely complex 3L of crude humic acid solution. Moreover, when the salt is washed and centrifuged in step 3 of the volume ratio, the crude humic acid iron solution with a conductivity of 3000 μs / cm cannot be completely precipitated by centrifugation, which is similar to the centrifugal property of humic acid at this conductivity, indicating that there are many sites of crude humic acid that have not combined with ferric chloride, the reaction is incomplete, and the volume of the ferric chloride solution should be increased. The color of the beaker of 30:30 is very deep, indicating that the volume ratio also causes a large amount of residual ferric chloride to be unused, resulting in waste.

[0074] In order to further determine that the color of the supernatant in the beaker is mainly presented by the residual ferric chloride, 20 mL of solution is taken from each beaker, and 10 mL of 0.1 mol / L sodium hydroxide solution is added, as shown in Figure 3 It can be seen that the colors of the first two gradients (30:10, 30:25) are green and blue-green, which are the colors of ferrous ions, and the colors of the last two gradients (30:20 and 30:30) are yellow, which are the colors of ferric ions, and are similar to the color of the formed ferrihydrite in the last beaker. This indicates that the color is indeed mainly presented by the iron ions, and the residual ferric chloride in the gradients 30:20 and 30:30 is not completely reacted.

[0075] Based on the above simple discussion, the most recommended volume ratio of crude humic acid and ferric chloride solution of the present application is 30:20-30:15.

[0076] Example 3

[0077] Effect of different aging times on preparation of wood-based peat humic acid iron

[0078] 100g of wood-based peat and 2L of sodium hydroxide solution are mixed and stirred thoroughly, and after centrifugation, the upper solution is collected, and the residue continues to be added with 1L of sodium hydroxide solution to repeat the above steps, and a total of 3L of crude humic acid solution is collected. Different volumes of 0.1 mol / L ferric chloride solution 2L are added while stirring. Three groups of aging times are set at 25°C, including 0 hours, 24 hours and 64 hours, and after aging, the solution is centrifuged and washed with water, and the product is obtained after purification to a conductivity of less than 100 μs / cm.

[0079] As can be seen from Example 2, both volume ratios of 30:15 and 30:20 can be used to prepare the product. In this experiment, the X-ray diffraction (XRD) patterns of the samples prepared using the two volume ratios and centrifuged immediately without aging time were compared, and the XRD patterns of the samples prepared using the volume ratios of 30:15 and 30:20 and aged for 24 hours and 64 hours, respectively, were compared.

[0080] As can be seen from Example 2, both volume ratios of 30:15 and 30:20 can be used to prepare the product. In this experiment, the X-ray diffraction (XRD) patterns of the samples prepared using the two volume ratios and centrifuged immediately without aging time were compared, and the XRD patterns of the samples prepared using the volume ratios of 30:15 and 30:20 and aged for 24 hours and 64 hours, respectively, were compared. Figure 4 As can be seen from Example 2, both volume ratios of 30:15 and 30:20 can be used to prepare the product. In this experiment, the X-ray diffraction (XRD) patterns of the samples prepared using the two volume ratios and centrifuged immediately without aging time were compared, and the XRD patterns of the samples prepared using the volume ratios of 30:15 and 30:20 and aged for 24 hours and 64 hours, respectively, were compared.

[0081] As can be seen from Example 2, both volume ratios of 30:15 and 30:20 can be used to prepare the product. In this experiment, the X-ray diffraction (XRD) patterns of the samples prepared using the two volume ratios and centrifuged immediately without aging time were compared, and the XRD patterns of the samples prepared using the volume ratios of 30:15 and 30:20 and aged for 24 hours and 64 hours, respectively, were compared.

[0082] Example 4

[0083] Effect of different aging temperatures on preparation of the product

[0084] 100g of wood peat was mixed with 2L of sodium hydroxide solution and stirred thoroughly. After centrifugation, the supernatant was collected, and the residue was added with 1L of sodium hydroxide solution and the above steps were repeated. A total of 3L of crude humic acid solution was collected. While stirring, 2L of 0.1mol / L ferric chloride solution was added. After being placed at room temperature (10-18℃ in winter and 30-35℃ in summer) and 25℃ (temperature-controlled incubator) for 24 hours, the product was obtained by centrifugation and washing with water until the electrical conductivity was less than 100μs / cm.

[0085] Results: There was no significant difference in the extraction process. Therefore, to reduce production costs, the product can be placed at room temperature.

[0086] Example 5

[0087] Effect of different wood peat moisture contents on preparation of the product

[0088] The steps and technical solutions of this experiment were the same, except that two types of wood peat raw materials were used: one was 100g of naturally air-dried wood peat (mass moisture content of 26%), and the other was 100g of wet wood peat (mass moisture content of 141%).

[0089] The conclusion of this experiment is that the air-dried wood peat has strong hydrophobicity, and the stirring time of step 1 should be lengthened to fully extract the humic acid. The use of a volume ratio of 30:20 can still produce the product, which to some extent indicates that the choice of the volume ratio for extraction is more related to the concentration of sodium hydroxide in the crude humic acid than to the mass of humic acid.

[0090] Example 6

[0091] Nutrient content analysis of the woody peat humic acid iron complex fertilizer prepared by the present application

[0092] The total nitrogen, total phosphorus, total potassium and total sulfur of the woody peat humic acid iron complex fertilizer product prepared by the present application were determined by the soil agricultural chemical analysis method compiled by Lu Rukun et al. The results are shown in Table 1. The content of nitrogen, phosphorus, potassium and sulfur nutrient elements in the woody peat humic acid iron complex fertilizer of the present application is 20.66 g / kg, 6.37 g / kg, 7.35 g / kg and 14.88 g / kg, respectively, which indicates that it can increase the content of soil nutrients such as nitrogen, phosphorus, potassium and sulfur after being applied to the soil.

[0093] Table 1 Nutrient content of the woody peat humic acid iron complex fertilizer

[0094]

[0095] Example 7

[0096] Microstructure and element composition analysis of the woody peat humic acid iron complex fertilizer prepared by the present application

[0097] The microstructure and element composition and distribution of the woody peat humic acid iron complex fertilizer product prepared by the present application were determined by a Raman field emission combined with an electron scanning microscope (TESCAN MAIA3 GMU). As shown in the electron micrograph of FIG. 1, the woody peat humic acid iron complex fertilizer of the present application has a small particle size of about 20 nm, indicating that it has a high reactivity. Figure 5 As shown in the energy spectrum analysis results of FIG. 2, the woody peat humic acid iron complex fertilizer of the present application is rich in nutrient elements such as carbon, iron, oxygen, nitrogen, phosphorus, potassium and sulfur, and a small amount of silicon and aluminum elements, and has the ability to effectively improve the content of nutrient elements in the cultivated soil. The semi-quantitative analysis results of carbon and iron elements are 43.1wt% and 12.9wt%, respectively, and the semi-quantitative analysis results of nitrogen, phosphorus and potassium elements are 4.1wt%, 1.5wt% and 1.1wt%, respectively. In addition, except for silicon and aluminum elements, the remaining various nutrient elements in the sample are uniformly distributed, which indicates that the complexing degree of the woody peat humic acid and iron (including ferrihydrite) is high and uniform. Figure 6 Application Example 1

[0098] Application of the woody peat humic acid iron prepared by the present application in improving the organic carbon content of newly renovated cultivated soil

[0099]

[0100] ​The loess soil in Huangmian village (N36°44'5", E109°34'28") of Baota district, Yan'an city, Shaanxi province was selected as the research object. The soil was newly cultivated by land reclamation and leveling project. The soil had very low organic matter and nutrient content, with soil organic matter of 2.10 g / kg, very poor nutrients, and high calcium carbonate content, with pH of 9.0. The 0-20 cm surface soil samples were collected as the research object after the completion of the land reclamation project. The samples were dried and passed through a 2 mm sieve before being stored in bags. The constant temperature indoor incubation experiment was conducted in an artificial climate incubator. Five treatments were set up (3 replicates for each treatment): ① control (CK), ② straw treatment (S), ③ humic acid treatment (HA), ④ biochar treatment (B), and ⑤ wood-based peat humic acid iron treatment (HA-Fe). The specific experimental steps were as follows: 500 g of soil was weighed into a 1 L plastic culture bottle, and 5 g C / kg soil of the four organic materials was added according to the C application rate. The organic materials and soil were mixed evenly, and deionized water was added to adjust the soil moisture content to 70% of the field water capacity. The soil was incubated in a 28°C artificial climate incubator for 100 days. The soil moisture content was maintained constant by weighing during the incubation period. After incubation, the soil organic carbon, total nitrogen, pH, and electrical conductivity were measured.

[0101] As shown in the results in Figure 7 , the addition of organic materials can significantly increase the organic carbon content of loess soil. Among them, the wood-based peat humic acid iron has a much higher effect on the increase of organic carbon in loess soil than the traditional fertilizing organic material of straw, which is 2.0 times that of straw, and is comparable to the effect of biochar and humic acid. Figure 8 The results show that wood-based peat humic acid iron can significantly increase the total nitrogen content of loess soil. Figure 9The results of Table 2 show that the application of the wood-based peat humic acid iron can increase the C / N ratio of the yellow-brown soil, and the increase is much greater than that of the straw, the biochar and the humic acid, which indicates that the wood-based peat humic acid iron mainly promotes the difficult-to-decompose organic matter of the yellow-brown soil, and the promoted organic matter has higher stability. In addition, the results of Table 2 show that the wood-based peat humic acid iron can also reduce the pH of the calcareous yellow-brown soil. Although the application of the wood-based peat humic acid iron can increase the salt content of the soil, the influence is smaller than that of the straw, the biochar and the humic acid. This indicates that the wood-based peat humic acid iron has the effect of improving the alkalinity of the calcareous soil and reducing the pH of the soil, and the influence on the increase of the soil conductivity is also smaller than that of the straw, the biochar and the humic acid. In summary, the application of the wood-based peat humic acid iron to the newly renovated farmland yellow-brown soil can significantly promote the content of the soil organic matter, especially the difficult-to-decompose organic matter, increase the nitrogen level of the soil, reduce the pH of the calcareous yellow-brown soil, and has a better effect on the salt content of the soil than the traditional improved organic materials such as the straw, the biochar and the humic acid.

[0102] Table 2 is the pH value and EC determination results of the improved soil in different treatment groups

[0103]

[0104] Application Example 2

[0105] The wood-based peat humic acid iron prepared by the application is applied to rapidly improve the soil structure of the newly renovated farmland.

[0106] The application example still selects the newly renovated farmland soil, i.e. the yellow-brown soil in the application example 1, as the research object of the embodiment. The experiment is divided into 6 treatments (3 repetitions for each treatment), which are: ① control (CK), ② straw treatment (S), ③ biochar treatment (B), ④ commercial humic acid treatment (HA), ⑤ half amount of wood-based peat humic acid iron treatment (1 / 2HA-Fe) and ⑥ full amount of wood-based peat humic acid iron treatment (HA-Fe). The specific experimental steps are as follows: 200g of soil sample passing through a 2mm sieve is weighed in a 1L plastic culture box, and 2.5g of C / kg of soil is added to the above-mentioned S, B, HA and HA-Fe, etc. 4 kinds of organic materials, and 1.25g of C / kg of half carbon is added to the above-mentioned half amount of wood-based peat humic acid iron (1 / 2HA-Fe). After the organic materials of each treatment are mixed with the soil sample in the culture box, the water content of the soil in the box is adjusted to 70% of the field water holding capacity, and placed in a 28℃ artificial climate incubator for constant temperature incubation for 2 weeks. The water content of the soil is maintained at a constant level by weighing during the whole incubation period. After the incubation is completed, the dried soil is taken out and the water stable aggregate of the 6 treatments is measured.

[0107] As Figure 10As shown in the results, after 2 weeks of short-term incubation, S and B treatments did not significantly increase the number of >2 mm and 2–0.25 mm macroaggregates compared with CK, and HA treatment did not significantly increase the number of 2–0.25 mm macroaggregates. In contrast, the addition of HA-Fe significantly increased the number of >2 mm and 0.25–2 mm macroaggregates after only 2 weeks. Compared with CK, HA-Fe increased the number of >2 mm macroaggregates by 54.7%, which was much higher than S, B, and HA treatments, which were 65.5, 201.1, and 6.3 times, respectively. The number of 2–0.25 mm macroaggregates in HA-Fe was also significantly higher than S, B, and HA treatments, which were 2.4, 3.9, and 3.3 times, respectively. In S, B, and HA treatments, the best-performing HA treatment increased the number of >2 mm macroaggregates by only half that of 1 / 2HA-Fe and much less than 1 / 2HA-Fe for 2–0.25 mm macroaggregates. In summary, the application of wood-based peat humic acid iron to newly renovated loessial soil can significantly and rapidly improve the stability of loessial soil aggregates and improve their structural conditions, with a much higher effect than traditional organic materials such as straw, biochar, and commercial humic acid.

Claims

1. A method for preparing a woody peat humic acid iron chelate fertilizer, characterized in that, The woody peat humic acid iron complex fertilizer is made from the following raw materials in the following proportions: 100g woody peat, 0.3mol sodium hydroxide, 0.15-0.3mol ferric chloride, 5-10g ammonium sulfate and 2-5g potassium dihydrogen phosphate; the moisture content of the woody peat is 100%-150%; Includes the following steps: Woody peat is mixed with an aqueous sodium hydroxide solution to obtain a crude woody peat humic acid solution. The mixing method is as follows: 100g of woody peat is mixed with 2L of 0.1mol / L aqueous sodium hydroxide solution, the supernatant is collected, and the remaining precipitate is mixed with 1L of 0.1mol / L aqueous sodium hydroxide solution, the supernatant is collected, and the two supernatants are combined to obtain the crude woody peat humic acid solution. An aqueous solution of ferric chloride was added to the coarse woody peat humic acid solution to make the pH of the resulting nano-iron ore system 2.0-2.

5. The nano-iron ore was aged, the solid phase was collected from the aged system, and the salt was removed by water washing until the conductivity was less than 100 μS / cm to obtain iron humate from woody peat. After the iron humate from the woody peat is purified by washing, ammonium sulfate and potassium dihydrogen phosphate are added while stirring to obtain iron humate chelate from the woody peat.

2. The production method according to claim 1, characterized by, The aging time is 24 to 64 hours.

3. The preparation method according to claim 1, characterized in that, The aging temperature is 10–35°C.

4. The application of the woody peat humic acid iron complex fertilizer obtained by the preparation method according to any one of claims 1 to 3 in improving newly reclaimed farmland soil.

5. The application according to claim 4, characterized in that, The newly renovated farmland has calcareous soil.

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