Special water-soluble cotton fertilizer taking cotton stalks as raw material and containing humic acid and mineral elements as well as preparation method and application of special water-soluble cotton fertilizer

Abstract

The invention discloses a special water-soluble cotton fertilizer which takes cotton stalks as a raw material and contains humic acid and mineral elements as well as a preparation method and application of the special water-soluble cotton fertilizer. The method effectively solves the problem of utilization of agriculture and forestry biomass solid wastes, and realizes full utilization and self-circulation of cotton mineral elements and organic matters. The cotton stalks serve as byproducts of cotton production and are rich in calcium, potassium, nitrogen, phosphorus, silicon and other elements, mineral elements and water-soluble humic acid / fulvic acid are extracted through a simple process to prepare the humic acid fertilizer, the humic acid fertilizer is applied to cotton again, nutrient elements needed by plants can be returned to soil while the yield of the crops is increased, and the quality of the cotton is improved. The agricultural renewable resource cotton stalk is fully utilized, the agricultural planting cost is reduced, and economic benefit maximization is promoted.

Description

Technical Field

[0001] The invention belongs to the field of solid waste resource utilization, and particularly relates to a water-soluble cotton-specific fertilizer containing humic acid and mineral elements and using cotton stalks as raw materials, and a preparation method and application thereof. Background Art

[0002] As one of the important economic crops in my country's agricultural production, cotton has been continuously expanded in planting area and production scale in recent years. Cotton stalks, as the main by-product of cotton, are mainly composed of cellulose, hemicellulose, and lignin. They also contain protein, vitamins, nitrogen, phosphorus, potassium, and trace elements. They are a high-quality agricultural renewable resource. After processing, cotton stalks can be used as fuel, feed, or fertilizer, and can also be used as industrial raw materials such as construction and packaging materials. At present, the main way to utilize cotton stalks is to directly crush and return them to the field. However, due to the special structure of cotton stalks and the relatively high degree of lignification, their effective degradation rate in the field is low, making it difficult to convert them into usable fertilizers. The comprehensive utilization technology of cotton stalk resources has many prominent problems such as insufficient innovation and low utilization efficiency, which restricts the effective utilization of cotton stalk resources and affects the cost saving and efficiency improvement and sustainable development of the cotton industry. Therefore, it is urgent to develop cotton stalk resource utilization technology.

[0003] Cotton needs a variety of nutrients such as nitrogen, phosphorus, potassium, calcium, and magnesium during its growth process, and cotton has its own rules for absorbing nutrients, and the types and quantities of nutrients required at different growth stages are also different. However, the nutrition directly provided by the soil is limited, and the nutritional requirements of cotton during its growth period cannot be guaranteed, which in turn affects the high and stable yield of cotton. Therefore, it is necessary to apply fertilizers additionally. There are many types of existing cotton fertilizers, among which cotton-specific fertilizers are mostly nitrogen, phosphorus, and potassium compound fertilizers, which are mainly composed of the three inorganic elements of nitrogen, phosphorus, and potassium. Long-term application will destroy the soil aggregate structure and easily cause soil compaction, thereby affecting the growth process of cotton. Although a single cotton organic fertilizer has a large organic matter content, the nutrients therein are difficult to release efficiently, which is not conducive to cotton absorption, and most fertilizers are not applied in a targeted manner according to the nutrient requirements of cotton during different growth periods. Therefore, it is necessary to develop cotton-specific fertilizers that can meet the nutritional element requirements of cotton during different growth periods.

[0004] Humic acid is an organic high molecular active substance, which is widely used in agriculture, forestry, animal husbandry, chemical industry, building materials, medicine and health, environmental protection and other fields. Studies have shown that humic acid has the functions of improving soil, promoting the formation of soil aggregate structure, improving soil water and fertilizer retention capacity, stimulating crop growth, etc. In recent years, with the continuous advancement of ecological agriculture construction, the promotion of organic fertilizers has alleviated the problem of blind and excessive application of chemical fertilizers to a large extent. Among them, humic acid fertilizers have attracted much attention due to their wide range of uses and pollution-free. Humic acid fertilizers are also widely used in cotton planting. However, the current preparation method of humic acid cotton special fertilizers, although partially solving the demand for nutrients in the growth process of cotton, has a high product cost, more requirements for the raw materials used, and the preparation process is complicated and uncontrollable. It is difficult to carry out targeted application according to the demand for nutrients in different growth periods of cotton, which needs further improvement. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a water-soluble cotton fertilizer containing humic acid and mineral elements using cotton stalks as raw materials.

[0006] Another object of the present invention is to provide a method for preparing the water-soluble cotton fertilizer containing humic acid and mineral elements using cotton stalks as raw materials.

[0007] Another object of the present invention is to provide application of the water-soluble cotton-specific fertilizer containing humic acid and mineral elements using cotton stalks as raw materials.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing a water-soluble cotton fertilizer containing humic acid and mineral elements using cotton stalks as raw materials comprises the following steps:

[0010] (1) crushing cotton stalks, drying, and sieving to obtain cotton stalk powder;

[0011] (2) mixing 100 parts by mass of cotton stalk powder with a hydrochloric acid solution, ultrasonicating, and filtering to obtain an acid-washed liquid product and an acid-washed solid product;

[0012] (3) adding 1 to 3 parts by weight of a chelating agent to the pickling liquid product, adjusting the pH, and stirring the reaction to obtain a chelating solution;

[0013] (4) adding 1 to 2 parts by weight of a catalyst to the acid-washed solid product, mixing, grinding, and roasting to obtain a weathered coal-like precursor;

[0014] (5) adding an oxidant solution to a weathered coal precursor, mixing and stirring to react, and filtering to obtain an oxidized liquid product and an oxidized solid product;

[0015] (6) adding an acid solution to the oxidized solid product, adjusting the pH, ultrasonicating, and drying to obtain a humic acid-containing fertilizer raw material;

[0016] (7) The chelating solution and the oxidized liquid product are mixed, stirred, dried and granulated to obtain a water-soluble cotton fertilizer containing humic acid and mineral elements.

[0017] The sieving in step (1) is through a 100-mesh sieve.

[0018] The ratio of the cotton stalk powder and the hydrochloric acid solution in step (2) is 1 g:5 mL.

[0019] The concentration of the hydrochloric acid solution in step (2) is 5%.

[0020] The ultrasonic condition in step (2) is 1 h at 25°C.

[0021] The chelating agent described in step (3) is at least one of EDTA, IDHA, DTPA and citric acid.

[0022] The pH adjustment in step (3) is to adjust the pH to 6-7.

[0023] The stirring reaction in step (3) is carried out for 30 to 90 minutes.

[0024] The catalyst in step (4) is Fe 2 O 3 、CuO、ZnCl 2 、FeCl 3 , FeOOH or at least one of the following.

[0025] The calcination conditions in step (4) are calcination at 200-300°C for 1-3h; preferably, the temperature is increased to 250°C at a rate of 10°C / min and calcined for 2h.

[0026] The oxidant solution in step (5) is H 2 O 2 NH 4 NO 3 , HNO 3 At least one of the solutions.

[0027] The concentration of the oxidant solution in step (5) is 2-4%.

[0028] The ratio of the oxidant solution described in step (5) to the cotton stalk powder described in step (1) is 1-3 mL: 1 g.

[0029] The mixing and stirring reaction in step (5) is carried out for 1 to 3 hours.

[0030] The pH adjustment in step (6) is to adjust the pH to 6-7.

[0031] The ultrasonic conditions in step (6) are as follows: frequency 60 kHz, power 500 W, temperature 50° C., and time 30 min.

[0032] The volume ratio of the chelating solution and the oxidation liquid product in step (7) is 1:2.

[0033] A water-soluble cotton-specific fertilizer containing humic acid and mineral elements and taking cotton stalks as raw materials is prepared according to the preparation method.

[0034] The water-soluble cotton fertilizer containing humic acid and mineral elements is used as cotton fertilizer.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] (1) The present invention effectively solves the problem of utilizing agricultural and forestry biomass solid waste, and realizes the full utilization and self-circulation of cotton mineral elements and organic matter. Cotton stalks, as a by-product of cotton production, are rich in calcium, potassium, nitrogen, phosphorus, silicon and other elements. Humic acid fertilizer is prepared by extracting mineral elements and water-soluble humic acid / fulvic acid through a simple process and then reapplied to cotton, which helps to return the nutrients needed by plants to the soil while increasing crop yields, making full use of cotton stalks, an agricultural renewable resource, reducing agricultural planting costs and maximizing economic benefits.

[0037] (2) As an organic fertilizer, the application of humic acid can effectively alleviate the problem of excessive use of traditional inorganic fertilizers and achieve fertilizer weight loss and efficiency improvement. The application of humic acid fertilizer can improve the bioavailability of nutrients (especially phosphorus) to crops and effectively improve nutrient efficiency; and humic acid can replace chelated and complexed heavy metal ions in the soil with its own ions, making heavy metal elements less likely to be absorbed by crops. In addition, humic acid can promote the formation of soil aggregates, improve soil ventilation and water permeability, and reduce the alkalinity of saline-alkali soil.

[0038] (3) Humic acid fertilizer has good water solubility and high fertilizer utilization rate. It is suitable for agricultural fertilization method of integrated water and fertilizer, especially for cotton-growing areas in water-poor areas in northwest my country.

[0039] (4) Biomass raw materials are renewable and easy to obtain, the fertilizer preparation process is simple, the production cost is low, the production process is green and environmentally friendly, and there is no discharge of "three wastes", which has good economic value and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of the present invention;

[0041] Figure 2This is the thermogravimetric diagram of the cotton stalk sample;

[0042] Figure 3 The comparison between the artificial humic acid from mineral source and the commercial humic acid from mineral source obtained in Example 1 is shown in FIG. 13 C NMR spectrum;

[0043] Figure 4 This is a comparison diagram of cotton growth when no fertilizer is applied to the soil before cotton planting and when the water-soluble cotton-specific fertilizer containing humic acid and mineral elements obtained in Example 1 is applied to the soil;

[0044] Figure 5 This is a scanning electron microscope image of the water-soluble cotton fertilizer containing humic acid and mineral elements obtained in Example 1. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0046] If no specific experimental conditions are specified in the following embodiments, conventional experimental conditions or experimental conditions recommended by the reagent company are generally followed. The materials and reagents used, unless otherwise specified, are all reagents and materials obtained from commercial sources.

[0047] Example 1

[0048] 1.1 Analysis of cotton stalk composition

[0049] Cotton stalks from a village in a county in Xinjiang were sawn into small sections of 5 to 8 cm, placed in an oven at 100 to 110°C and dried to constant weight to obtain dry cotton stalks, which were then placed in a crusher for crushing and grinding and passed through a 100-mesh sieve to obtain cotton stalk powder. The prepared cotton stalk powder was placed in a vacuum drying dish for later use.

[0050] Take an appropriate amount of cotton stalk powder for thermogravimetric analysis to explore its calcination reaction temperature. Figure 2 It can be seen that the decomposition rate of cotton stalk is faster at 200-300℃, so the roasting temperature range is determined to be 200-300℃.

[0051] In order to detect the elemental composition of cotton stalks, cotton stalk powder was treated at high temperature to obtain ash. 10g of cotton stalk powder was weighed, roasted at 600℃ for 2h, and then naturally dried at room temperature. After drying, it was weighed. The organic matter content of the cotton stalk was calculated based on the mass difference before and after roasting. The organic matter content in the cotton stalk was 92.27%.

[0052]

[0053] XRF analysis was performed on the cotton stalk samples roasted into ash to determine their elemental composition. The measured element content needed to be multiplied by the organic matter content of the cotton stalk to obtain the actual element content in the cotton stalk. Calculation showed that 1g of cotton stalk contained 0.302g of potassium, 0.245g of calcium, 0.097g of magnesium, 0.086g of silicon, and 0.042g of phosphorus. In addition, it also contained a variety of mineral elements, which can provide rich nutrient elements for the preparation of multi-element chelated liquid fertilizer.

[0054] The specific components of cotton stalks are shown in Tables 1 and 2.

[0055] Table 1 Basic components of cotton stalk

[0056]

[0057] Table 2 Element content of cotton stalk

[0058]

[0059]

[0060] 1.2 Preparation of water-soluble fertilizer using cotton stalks as raw materials

[0061] (1) Weigh 100 g of dried, crushed, and ground cotton stalk powder that has passed through a 100-mesh sieve;

[0062] (2) mixing the cotton stalk powder and 500 mL of 5% HCl solution uniformly, subjecting the mixture to ultrasonic treatment at 25° C. for 1 h to fully react, and then filtering the mixture with a 0.45 μm filter membrane to separate the solid from the liquid to obtain an acid-washed liquid product and an acid-washed solid product;

[0063] (3) adding 2 g of EDTA (chelating agent) to the separated acid-washed liquid product, adjusting the pH value of the liquid to 6.5 with a 1 mol / L KOH solution, and magnetically stirring for 1 h to allow chelation to obtain a multi-element chelated liquid fertilizer A;

[0064] (4) Add 1.5 g Fe 2 O 3 (catalyst), after mixing, fully grind, adjust the oxygen content of the calcination atmosphere to 10%, and program the temperature at a rate of 10°C / min, and calcine at 250°C for 2h to obtain a weathered coal precursor;

[0065] (5) The weathered coal precursor was mixed with 200 mL 3% H 2 O 2 The solution (oxidant aqueous solution) is mixed, magnetically stirred for 2 hours to fully react, and then filtered with a 0.45 μm filter membrane to separate the solid and liquid to obtain an oxidized liquid product and an oxidized solid product;

[0066] (6) Add an appropriate amount of dilute sulfuric acid to the separated oxidized solid product and adjust the pH to 6.5. Then activate it by ultrasound at a frequency of 60 kHz, a power of 500 W, a temperature of 50° C., and a time of 30 min. Then dry it at 40° C. to obtain a humic acid-containing fertilizer raw material;

[0067] (7) The separated oxidized liquid product is liquid fertilizer B containing humic acid / fulvic acid. Liquid fertilizer A and liquid fertilizer B are mixed in a volume ratio of 1:2, and magnetic stirring is performed for 1 hour to make the mixture evenly mixed. After concentration and granulation, a water-soluble cotton-specific fertilizer solid product containing humic acid and mineral elements is obtained.

[0068] Table 3 Technical index test results of water-soluble fertilizer solid products

[0069]

[0070] Comparative Example 1

[0071] (1) Weigh 100 g of dried, crushed, and ground cotton stalk powder that has passed through a 100-mesh sieve;

[0072] (2) mixing the cotton stalk powder and 500 mL of 5% HCl solution uniformly, subjecting the mixture to ultrasonic treatment at 25° C. for 1 h to fully react, and then filtering the mixture with a 0.45 μm filter membrane to separate the solid from the liquid to obtain an acid-washed liquid product and an acid-washed solid product;

[0073] (3) adding 2 g of EDTA (chelating agent) to the separated acid-washed liquid product, adjusting the pH value of the liquid to 6.5 with a 1 mol / L KOH solution, and magnetically stirring for 1 h to allow chelation to obtain a multi-element chelated liquid fertilizer A;

[0074] (4) roasting the separated acid-washed solid product, adjusting the oxygen content of the roasting atmosphere to 10%, and heating at a rate of 10° C. / min, and roasting at 250° C. for 2 h to obtain a weathered coal precursor;

[0075] (5) The weathered coal precursor was mixed with 200 mL 3% H 2 O 2 The solution (oxidant aqueous solution) is mixed, magnetically stirred for 2 hours to fully react, and then filtered with a 0.45 μm filter membrane to separate the solid and liquid to obtain an oxidized liquid product and an oxidized solid product;

[0076] (6) Add an appropriate amount of dilute sulfuric acid to the separated oxidized solid product and adjust the pH to 6.5. Then activate it by ultrasound at a frequency of 60 kHz, a power of 500 W, a temperature of 50° C., and a time of 30 min. Then dry it at 40° C. to obtain a humic acid-containing fertilizer raw material;

[0077] (7) The separated oxidized liquid product is liquid fertilizer B containing humic acid / fulvic acid. Liquid fertilizer A and liquid fertilizer B are mixed in a volume ratio of 1:2, and magnetic stirring is performed for 1 hour to make the mixture evenly mixed. After concentration and granulation, a water-soluble cotton-specific fertilizer solid product containing humic acid and mineral elements is obtained.

[0078] Table 4 shows the yields of humic acid prepared by Example 1 and Comparative Example 1. It can be seen from the table that the yield of Example 1 is higher, indicating that the addition of a catalyst can increase the yield of humic acid.

[0079] Table 4 Yield of humic acid from different treatments

[0080]

[0081] Example 2

[0082] (1) Weigh 100 g of dried, crushed, and ground cotton stalk powder that has passed through a 100-mesh sieve;

[0083] (2) mixing the cotton stalk powder and 700 mL of 5% HCl solution uniformly, subjecting the mixture to ultrasonic treatment at 25° C. for 1 h to fully react, and then filtering the mixture with a 0.45 μm filter membrane to separate the solid from the liquid to obtain an acid-washed liquid product and an acid-washed solid product;

[0084] (3) adding 1.5 g IDHA (chelating agent) to the separated acid-washed liquid product, adjusting the pH value of the liquid to 6.0 with 1 mol / L KOH solution, and magnetically stirring for 1 h to chelate the liquid to obtain a multi-element chelated liquid fertilizer A;

[0085] (4) adding 1 g of CuO (catalyst) to the separated acid-washed solid product, mixing and grinding the mixture thoroughly, adjusting the oxygen content of the calcination atmosphere to 15%, and heating the mixture at a rate of 10° C. / min, and calcining the mixture at 200° C. for 2 h to obtain a weathered coal precursor;

[0086] (5) The weathered coal precursor was mixed with 300 mL 3% NH 4 NO 3 The solution (oxidant aqueous solution) is mixed, magnetically stirred for 2 hours to fully react, and then filtered with a 0.45 μm filter membrane to separate the solid and liquid to obtain an oxidized liquid product and an oxidized solid product;

[0087] (6) Add an appropriate amount of dilute sulfuric acid to the separated oxidized solid product and adjust the pH to 6.5. Then activate it by ultrasound at a frequency of 60 kHz, a power of 500 W, a temperature of 50° C., and a time of 30 min. Then dry it at 40° C. to obtain a humic acid-containing fertilizer raw material;

[0088] (7) The separated oxidized liquid product is liquid fertilizer B containing humic acid / fulvic acid. Liquid fertilizer A and liquid fertilizer B are mixed in a volume ratio of 1:2, and magnetic stirring is performed for 1 hour to make the mixture evenly mixed. After concentration and granulation, a water-soluble cotton-specific fertilizer solid product containing humic acid and mineral elements is obtained.

[0089] Example 3

[0090] (1) Weigh 100 g of dried, crushed, and ground cotton stalk powder that has passed through a 100-mesh sieve;

[0091] (2) mixing the cotton stalk powder and 500 mL of 5% HCl solution uniformly, subjecting the mixture to ultrasonic treatment at 25° C. for 1 h to fully react, and then filtering the mixture with a 0.45 μm filter membrane to separate the solid from the liquid to obtain an acid-washed liquid product and an acid-washed solid product;

[0092] (3) adding 3 g of DTPA (chelating agent) to the separated acid-washed liquid product, adjusting the pH value of the liquid to 5.0 with a 1 mol / L KOH solution, and magnetically stirring for 1 h to allow chelation to obtain a multi-element chelated liquid fertilizer A;

[0093] (4) Add 2 g ZnCl 2 (catalyst), after mixing, fully grind, adjust the oxygen content of the calcination atmosphere to 5%, and program the temperature at a rate of 10°C / min, and calcine at 250°C for 2.5h to obtain a weathered coal precursor;

[0094] (5) The weathered coal precursor was mixed with 400 mL 1% HNO 3 The solution (oxidant aqueous solution) is mixed, magnetically stirred for 2 hours to fully react, and then filtered with a 0.45 μm filter membrane to separate the solid and liquid to obtain an oxidized liquid product and an oxidized solid product;

[0095] (6) Add an appropriate amount of dilute sulfuric acid to the separated oxidized solid product and adjust the pH to 6.5. Then activate it by ultrasound at a frequency of 60 kHz, a power of 500 W, a temperature of 50° C., and a time of 30 min. Then dry it at 40° C. to obtain a humic acid-containing fertilizer raw material;

[0096] (7) The separated oxidized liquid product is liquid fertilizer B containing humic acid / fulvic acid. Liquid fertilizer A and liquid fertilizer B are mixed in a volume ratio of 1:2, and magnetic stirring is performed for 1 hour to make the mixture evenly mixed. After concentration and granulation, a water-soluble cotton-specific fertilizer solid product containing humic acid and mineral elements is obtained.

[0097] Example 4

[0098] (1) Weigh 100 g of dried, crushed, and ground cotton stalk powder that has passed through a 100-mesh sieve;

[0099] (2) mixing the cotton stalk powder and 600 mL of 5% HCl solution uniformly, subjecting the mixture to ultrasonic treatment at 25° C. for 1 h to allow the mixture to fully react, and then filtering the mixture with a 0.45 μm filter membrane to separate the solid from the liquid to obtain an acid-washed liquid product and an acid-washed solid product;

[0100] (3) adding 1 g of citric acid (chelating agent) to the separated pickled liquid product, adjusting the pH value of the liquid to 6.5 with 1 mol / L KOH solution, and magnetically stirring for 1 h to chelate the liquid to obtain a multi-element chelated liquid fertilizer A;

[0101] (4) Add 2 g FeCl 3 (catalyst), after mixing, fully grind, adjust the oxygen content of the calcination atmosphere to 10%, and program the temperature at a rate of 10°C / min, and calcine at 200°C for 2.5h to obtain a weathered coal precursor;

[0102] (5) The weathered coal precursor was mixed with 200 mL 2% HNO 3 The solution (oxidant aqueous solution) is mixed, magnetically stirred for 2 hours to fully react, and then filtered with a 0.45 μm filter membrane to separate the solid and liquid to obtain an oxidized liquid product and an oxidized solid product;

[0103] (6) Add an appropriate amount of dilute sulfuric acid to the separated oxidized solid product and adjust the pH to 6.5. Then activate it by ultrasound at a frequency of 60 kHz, a power of 500 W, a temperature of 50° C., and a time of 30 min. Then dry it at 40° C. to obtain a humic acid-containing fertilizer raw material;

[0104] (7) The separated oxidized liquid product is liquid fertilizer B containing humic acid / fulvic acid. Liquid fertilizer A and liquid fertilizer B are mixed in a volume ratio of 1:2, and magnetic stirring is performed for 1 hour to make the mixture evenly mixed. After concentration and granulation, a water-soluble cotton-specific fertilizer solid product containing humic acid and mineral elements is obtained.

[0105] Example 5

[0106] (1) Weigh 100 g of dried, crushed, and ground cotton stalk powder that has passed through a 100-mesh sieve;

[0107] (2) mixing the cotton stalk powder and 500 mL of 5% HCl solution uniformly, subjecting the mixture to ultrasonic treatment at 25° C. for 1 h to fully react, and then filtering the mixture with a 0.45 μm filter membrane to separate the solid from the liquid to obtain an acid-washed liquid product and an acid-washed solid product;

[0108] (3) adding 3 g of EDTA (chelating agent) to the separated acid-washed liquid product, adjusting the pH value of the liquid to 6.5 with a 1 mol / L KOH solution, and magnetically stirring for 1 h to chelate the liquid to obtain a multi-element chelated liquid fertilizer A;

[0109] (4) Add 0.5 g Fe 2 O 3 , 0.5 g FeOOH (catalyst), mix and grind thoroughly, adjust the oxygen content of the calcination atmosphere to 5%, and program the temperature at a rate of 10 ° C / min, and calcine at 250 ° C for 2 h to obtain a weathered coal precursor;

[0110] (5) The weathered coal precursor was mixed with 150 mL 4% H 2 O 2 The solution (oxidant aqueous solution) is mixed, magnetically stirred for 2 hours to fully react, and then filtered with a 0.45 μm filter membrane to separate the solid and liquid to obtain an oxidized liquid product and an oxidized solid product;

[0111] (6) Add an appropriate amount of dilute sulfuric acid to the separated oxidized solid product and adjust the pH to 6.5. Then activate it by ultrasound at a frequency of 60 kHz, a power of 500 W, a temperature of 50° C., and a time of 30 min. Then dry it at 40° C. to obtain a humic acid-containing fertilizer raw material;

[0112] (7) The separated oxidized liquid product is liquid fertilizer B containing humic acid / fulvic acid. Liquid fertilizer A and liquid fertilizer B are mixed in a volume ratio of 1:2, and magnetic stirring is performed for 1 hour to make the mixture evenly mixed. After concentration and granulation, a water-soluble cotton-specific fertilizer solid product containing humic acid and mineral elements is obtained.

[0113] Test Example 1

[0114] Field tests were conducted at a cotton planting base in Xinjiang to test the effects of the water-soluble cotton-specific fertilizer solid products containing mineral-source artificial humic acid and self-produced mineral elements obtained in Comparative Example 1 and Examples 1 to 5 of the present invention.

[0115] Test cotton variety: Xinluzao 74.

[0116] Test method: The test field is divided into 6 plots, each of 1 mu. The test group uses the water-soluble cotton fertilizer containing mineral-source artificial humic acid and self-produced mineral elements prepared in Comparative Example 1 and Examples 1 to 5 as cotton bud stage and flower and boll stage special fertilizers. Each application is mixed with 300 times water and diluted for drip irrigation. The bud stage is applied once within one week after the cotton buds appear at a dosage of 25 kg per mu; the flower and boll stage is applied twice, after the cotton buds are initially opened and fully bloomed, and the application amount is 20 kg per mu each time. The control group does not apply the formula fertilizer of the present invention, but applies commercially available solid nitrogen, phosphorus and potassium compound fertilizers. According to the local cotton fertilization habits, the inorganic fertilizer application amount is designed to be 200 kg per mu, divided into three applications, and each application is one month apart. Finally, the cotton yield is counted during the cotton harvest period, and the yield increase rate is calculated. The results are shown in Table 5; at the same time, the 0-20 cm tillage layer soil is collected after the cotton is harvested, and the physical and chemical properties of the soil are tested. The analysis results are shown in Table 6.

[0117] Table 5 Comparison results of cotton yield

[0118]

[0119] Table 6 Analysis results of soil properties in the cultivated layer

[0120]

[0121] The data results in Table 5 show that the cotton yield of the water-soluble cotton-specific fertilizer containing mineral-like artificial humic acid and self-produced mineral elements prepared in Examples 1 to 5 is significantly higher than that of the control group using commercially available solid nitrogen, phosphorus and potassium compound fertilizers, and the yield increase rate of cotton is 15.83-23.12%. Although the cotton yield of the water-soluble cotton-specific fertilizer containing mineral-like artificial humic acid and self-produced mineral elements prepared in Comparative Example 1 is higher than that of the control group using commercially available solid nitrogen, phosphorus and potassium compound fertilizers, the yield increase effect is not as obvious as that of Examples 1 to 5. This shows that the cotton-specific fertilizer provided by the present invention is rich in nutrient elements and has a reasonable ratio, and has a good yield increase effect on cotton planting.

[0122] The data results in Table 6 show that the water-soluble cotton-specific fertilizer containing mineral-based artificial humic acid and its own mineral elements has the effects of soil improvement and fertilization, can effectively increase the nutrient content of the soil, promote the utilization of nutrients by crops, and increase soil permeability, which is not only helpful to the crops themselves, but also can improve the soil conditions for crop growth.

[0123] Test Example 2

[0124] A field test was conducted at a cotton planting base in Xinjiang to test the effect of applying the humic acid-based fertilizer product and the fulvic acid water-soluble fertilizer product prepared by the present invention when planting cotton year after year.

[0125] Test cotton variety: Xinluzao 74.

[0126] Test method: A 1-mu test field was designated, and four crops of cotton were planted continuously. The cotton stalks of the previous crop were harvested, and a water-soluble cotton fertilizer product containing mineral-like artificial humic acid and self-produced mineral elements was prepared according to the method of Example 1, and the product was applied during the planting of the next crop of cotton. The yield of cotton was counted during each planting at the cotton harvest period, and the results are shown in Table 7.

[0127] Table 7 Comparison results of cotton continuous cropping yield

[0128]

[0129]

[0130] The data results in Table 7 show that the cotton yield is effectively improved and gradually stabilized by continuously applying the product of the present invention prepared by cotton stalks. Cotton stalks are rich in nitrogen, phosphorus, potassium, calcium, organic matter, trace elements, etc., which can balance the nutrients required for cotton growth. The present invention realizes the effective circulation of cotton mineral elements, helps to return the nutrients required by plants to the soil while increasing crop yields, and thus does not need to be planted in rotation.

[0131] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a water-soluble cotton fertilizer containing humic acid and mineral elements using cotton stalks as raw materials, characterized in that The steps include: (1) crushing cotton stalks, drying, and sieving to obtain cotton stalk powder; (2) mixing 100 parts by mass of cotton stalk powder with a hydrochloric acid solution, ultrasonicating, and filtering to obtain an acid-washed liquid product and an acid-washed solid product; (3) adding 1 to 3 parts by weight of a chelating agent to the pickling liquid product, adjusting the pH, and stirring the reaction to obtain a chelating solution; (4) adding 1 to 2 parts by weight of a catalyst to the acid-washed solid product, mixing, grinding, and roasting to obtain a weathered coal-like precursor; (5) adding an oxidant solution to a weathered coal precursor, mixing and stirring to react, and filtering to obtain an oxidized liquid product and an oxidized solid product; (6) adding an acid solution to the oxidized solid product, adjusting the pH, ultrasonicating, and drying to obtain a humic acid-containing fertilizer raw material; (7) The chelating solution and the oxidized liquid product are mixed, stirred, dried and granulated to obtain a water-soluble cotton fertilizer containing humic acid and mineral elements.

2. The preparation method according to claim 1, characterized in that: The sieving in step (1) is through a 100 mesh sieve; The ultrasonic condition in step (2) is 1 h at 25°C.

3. The preparation method according to claim 1, characterized in that: The ratio of the cotton stalk powder and the hydrochloric acid solution in step (2) is 1 g: 5 mL; The concentration of the hydrochloric acid solution in step (2) is 5%.

4. The preparation method according to claim 1, characterized in that: The chelating agent in step (3) is at least one of EDTA, IDHA, DTPA and citric acid; The pH adjustment in step (3) is to adjust the pH to 6-7; The stirring reaction in step (3) is carried out for 30 to 90 minutes.

5. The preparation method according to claim 1, characterized in that: The catalyst described in step (4) is at least one of Fe2O3, CuO, ZnCl2, FeCl3, and FeOOH.

6. The preparation method according to claim 1, characterized in that: The calcination conditions in step (4) are calcination at 200-300° C. for 1-3 hours.

7. The preparation method according to claim 1, characterized in that: The oxidant solution in step (5) is at least one of H2O2, NH4NO3, and HNO3 solutions; The concentration of the oxidant solution in step (5) is 2-4%; The ratio of the oxidant solution in step (5) to the cotton stalk powder in step (1) is 1-3 mL: 1 g; The mixing and stirring reaction in step (5) is carried out for 1 to 3 hours.

8. The preparation method according to claim 1, characterized in that: The pH adjustment in step (6) is to adjust the pH to 6-7; The ultrasonic conditions in step (6) are as follows: frequency 60 kHz, power 500 W, temperature 50° C., and time 30 min; The volume ratio of the chelating solution and the oxidation liquid product in step (7) is 1:

2.

9. A water-soluble cotton fertilizer containing humic acid and mineral elements using cotton stalks as raw materials, prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the water-soluble cotton fertilizer containing humic acid and mineral elements made from cotton stalks as claimed in claim 9 as a cotton fertilizer.

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