Peat water-retaining fertilizer and preparation method thereof

Abstract

The invention relates to the technical field of agricultural fertilizers, in particular to a peat water-retaining fertilizer and a preparation method thereof, and the peat water-retaining fertilizer comprises the following raw materials in parts by mass: 700-900 parts of a large granular urea aqueous solution, 60-100 parts of peat, 40-50 parts of an inorganic fertilizer, 25-35 parts of an organic fertilizer, 5-10 parts of modified humic acid, 2-8 parts of water-retaining gel and 5-10 parts of a filler. The peat water-retaining fertilizer provided by the invention has excellent water-retaining capacity and good heavy metal ion removal capacity, and can improve the soil environment so as to promote the growth of crops.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of agricultural fertilizer, in particular to a peat water-retaining fertilizer and a preparation method thereof. BACKGROUND

[0002] Peat, as a natural organic resource with a long history, plays an irreplaceable role in the sustainable development of agriculture due to its water and fertilizer retention characteristics. Peat is mainly formed by the accumulation of plant residues in a low-temperature, anaerobic swamp environment over thousands of years, and is rich in undecomposed cellulose, lignin, and humic acid organic matter, with an organic matter content of typically 40%-95%. This unique formation process endows peat with a loose and porous structure, enabling it to have excellent physical regulation capabilities: on the one hand, it can adsorb several times its own weight of water, alleviating drought stress; on the other hand, through the ion exchange of humic acid, it can fix nutrients such as nitrogen, phosphorus, and potassium, reducing loss and achieving the effect of "water retention like a sponge and fertilizer retention like a magnet".

[0003] In terms of soil improvement, peat fertilizer exhibits multiple ecological values. The problems of soil compaction and salinization caused by long-term application of chemical fertilizers are becoming increasingly serious, while peat can promote the formation of soil aggregate structure, coordinate water, air, and heat balance, and enhance microbial activity. Studies have shown that the addition of peat can increase root development in soil by 40% and improve phosphorus fertilizer utilization by more than 100%. Especially in the treatment of saline-alkali soil, peat combined with vegetation planting can significantly reduce soil salt content. Its water retention characteristics reduce evaporation and inhibit the upward movement of salt, allowing areas that were previously unable to be cultivated to be transformed into high-yield farmland.

[0004] However, there are still many problems in the application of peat fertilizer at present. For example, patent number CN1796337A discloses "peat biological compound microbial fertilizer and its production process", which is mainly a secondary expansion culture solution prepared by using peat, potassium feldspar powder, and phosphorite powder as carriers, and white sugar, potassium dihydrogen phosphate, magnesium sulfate, sodium chloride, calcium sulfate, potassium feldspar powder, etc. as raw materials. The solid carrier is mixed with the culture solution to prepare a peat biological compound microbial fertilizer. The advantages of this invention are: simplifying the production process, continuously providing effective potassium and nitrogen for plants, and promoting plant growth and development. However, the content of heavy metal ions in the soil of some areas is high, which hinders the normal growth of plants. The above-mentioned disclosed patent does not add raw materials that can effectively complex heavy metals, and the ability to remove heavy metals is limited.

[0005] Therefore, there is an urgent need to develop a water-retaining fertilizer with strong water-retaining capacity and the ability to remove heavy metal ions from soil. SUMMARY

[0006] The purpose of the present application is to provide a peat water-retaining fertilizer and a preparation method thereof, to solve the problem of weak water-retaining capacity and weak heavy metal ion removal ability of current fertilizers.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The present invention provides a peat water-retaining fertilizer, comprising the following raw materials in parts by weight: 700-900 parts of a 44-46 wt% granular urea aqueous solution, 60-100 parts of peat, 40-50 parts of inorganic fertilizer, 25-35 parts of organic fertilizer, 5-10 parts of modified humic acid, 2-8 parts of water-retaining gel, and 5-10 parts of filler.

[0008] This invention uses large-particle urea aqueous solution, peat, inorganic fertilizer, organic fertilizer, modified humic acid, water-retaining gel and filler as main raw materials to prepare a peat water-retaining fertilizer. This peat water-retaining fertilizer has good water retention capacity and can remove heavy metal ions in the soil, thus improving the soil environment.

[0009] In some embodiments, the inorganic fertilizer is a mixture of superphosphate, monoammonium phosphate, chelated iron, potassium sulfate, chelated zinc and sodium octaborate tetrahydrate, in a mass ratio of 1:(0.4~0.6):(0.08~0.15):(0.4~0.6):(0.06~0.1):(0.06~0.1).

[0010] Preferably, the inorganic fertilizer is a mixture of superphosphate, monoammonium phosphate, chelated iron, potassium sulfate, chelated zinc and sodium octaborate tetrahydrate, in a mass ratio of 1:0.5:0.1:0.5:0.08:0.08.

[0011] In some embodiments, the organic fertilizer is one or more of rapeseed cake powder, bone meal, mushroom residue, and grape residue.

[0012] In some embodiments, the method for preparing the modified humic acid includes the following steps: A1. Mix humic acid with 13-16 wt% dilute sulfuric acid, heat to 45-55℃ and stir for 3-4 hours, then dry under reduced pressure to obtain pretreated humic acid. A2. Under an inert protective gas atmosphere, the pretreated humic acid from step A1 is mixed with acrylic acid and added to toluene. An initiator is added, and the mixture is heated to 65~75℃ and stirred at a constant temperature for 5~6 hours. After the mixture is heated, it is concentrated under reduced pressure and dried to obtain a polyacrylic acid modified humic acid composite. A3. Under an inert protective gas atmosphere, the polyacrylic acid modified humic acid complex from step A2 is mixed with trehalose, and the mixture is heated and stirred to obtain modified humic acid.

[0013] This invention first pretreats humic acid with sulfuric acid, which sulfonates the humic acid. Then, the pretreated humic acid is mixed with acrylic acid, and polyacrylic acid is grafted into the humic acid structure under the action of an initiator. Trehalose is then introduced, forming a modified humic acid with a three-dimensional cross-linked network structure through hydrogen and chemical bonds. This modified humic acid has a certain water retention capacity and excellent adsorption capacity, capable of adsorbing heavy metal ions in the soil, thereby improving the soil environment and promoting plant growth. The reason for this may be that the sulfonic acid groups can dissociate into -SO3 in the soil solution. - By capturing positively charged heavy metal ions through electrostatic attraction, the selective adsorption capacity for low-concentration heavy metals is enhanced. At the same time, acrylic acid provides a large number of carboxyl groups, which can chelate heavy metal ions to form stable five-membered ring chelates. The introduction of trehalose forms a framework structure with humic acid and acrylic acid, exposing more adsorption sites and improving the stability of modified humic acid.

[0014] In some embodiments, in step A1, the mass-to-volume ratio of humic acid to dilute sulfuric acid is 1:(0.9~1.1).

[0015] In some embodiments, in step A2, the mass ratio of pretreated humic acid to acrylic acid is 1:(1~1.4).

[0016] Preferably, in step A2, the mass ratio of pretreated humic acid to acrylic acid is 1:1.2.

[0017] This application enables the carboxyl groups in the humic acid structure to retain some activity by adjusting the mass ratio of pretreated humic acid to acrylic acid, allowing them to crosslink with trehalose to obtain a three-dimensional network structure.

[0018] In some embodiments, the initiator in step A2 is azobisisobutyronitrile.

[0019] In some embodiments, in step A2, the amount of initiator added is 0.004 to 0.006 times the mass of the pretreated humic acid.

[0020] In some embodiments, in step A3, the mass ratio of the polyacrylic acid modified humic acid complex to trehalose is 1:(0.9~1.2).

[0021] Preferably, in step A3, the mass ratio of the polyacrylic acid modified humic acid complex to trehalose is 1:1.

[0022] This application improves the adsorption capacity of modified humic acid by adjusting the mass ratio of polyacrylic acid-modified humic acid complex to trehalose, thereby enabling the active groups in humic acid to crosslink more completely with trehalose.

[0023] In some embodiments, in step A3, the temperature rise rate is 2~4℃ / min, the temperature is 170~190℃, and the stirring time is 50~60min.

[0024] Preferably, in step A3, the temperature rise rate is 3℃ / min, the temperature is 180℃, and the stirring time is 55min.

[0025] In some embodiments, the water-retaining gel is an acrylic-acrylamide gel.

[0026] In some embodiments, the filler is any one or more of diatomaceous earth, attapulgite, and bentonite.

[0027] Another aspect of the present invention provides a method for preparing peat water-retaining fertilizer, comprising the following steps: (1) The organic fertilizer is decomposed and then mixed with the inorganic fertilizer, granulated and dried to obtain a compound solid fertilizer; (2) The composite solid fertilizer is mixed with modified humic acid, water-retaining gel and filler, and then swollen in a large particle urea aqueous solution. Then the composite solid fertilizer in step (1) is added and granulated in a granulator. After air drying, it is mixed with peat to obtain peat water-retaining fertilizer.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses large-particle urea aqueous solution, peat, inorganic fertilizer, organic fertilizer, modified humic acid, water-retaining gel and filler as the main raw materials to prepare a peat water-retaining fertilizer. The peat water-retaining fertilizer has good water retention capacity and can remove heavy metal ions in the soil and improve the soil environment.

[0029] (2) The sulfonic acid group in the modified humic acid structure of the present invention can dissociate into -SO3 in soil solution. - By capturing positively charged heavy metal ions through electrostatic attraction, the selective adsorption capacity for low-concentration heavy metals is enhanced. At the same time, acrylic acid provides a large number of carboxyl groups, which can chelate heavy metal ions to form stable five-membered ring chelates. The introduction of trehalose forms a framework structure with humic acid and acrylic acid, exposing more adsorption sites and improving the stability of modified humic acid. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0031] Unless otherwise specified, the post-processing operations described below, such as "reduced pressure drying", "mixing", "heating", "stirring", "granulation", "air drying", "air drying", and "fermentation", can be selected by those skilled in the art based on actual conditions, and are not further limited.

[0032] The parameters for the composting process are as follows: Day 1 to 5: during the warming period, the temperature rises from 25℃ to 30℃ to 50℃ to 55℃; Day 6 to 15: during the constant temperature period, the temperature stabilizes at 55℃ to 65℃; Day 16 to 22: the temperature naturally drops to 40℃ to 45℃; Day 23 to 40: during the maturation stage, the temperature drops to 30℃ to 35℃, maintaining a moisture content of 50% to 55%.

[0033] Acrylic acid-acrylamide gel was purchased from Xi'an Ruixi Biotechnology Co., Ltd.; the large-particle urea aqueous solution was prepared by mixing large-particle urea (purchased from Shandong Guangxun Chemical Co., Ltd.) with deionized water according to the mass concentrations described in the following embodiments.

[0034] Preparation Example 1 The preparation method of modified humic acid includes the following steps: A1. Mix 10g of humic acid with 10ml of 15wt% dilute sulfuric acid, heat to 50℃ and stir for 3h, then dry under reduced pressure to obtain pretreated humic acid. A2. Under N2 atmosphere, 10g of pretreated humic acid and 12g of acrylic acid from step A1 were mixed and added to 150ml of toluene. 0.05g of azobisisobutyronitrile was added, and the mixture was heated to 70℃ and stirred at a constant temperature for 5h. After the reaction was completed, the mixture was concentrated under reduced pressure and dried to obtain polyacrylic acid modified humic acid composite. A3. Under N2 atmosphere, mix 10g of the polyacrylic acid modified humic acid complex from step A2 with 11g of trehalose, raise the temperature to 180℃ at a heating rate of 3℃ / min and stir for 50min to obtain modified humic acid.

[0035] Preparation Example 2 The preparation method of modified humic acid is the same as that in Preparation Example 1, except that the amount of acrylic acid is 17g.

[0036] Preparation Example 3 The preparation method of modified humic acid is the same as that in Preparation Example 1, except that the amount of acrylic acid is 8g.

[0037] Preparation Example 4 The preparation method of modified humic acid is the same as that in Preparation Example 1, except that the amount of trehalose is 7g.

[0038] Example 1 A peat water-retaining fertilizer comprises the following raw materials in parts by weight: 800 parts of 45wt% granular urea aqueous solution, 80 parts of peat, 45 parts of inorganic fertilizer, 30 parts of organic fertilizer, 7 parts of modified humic acid, 5 parts of acrylic acid-acrylamide gel, and 8 parts of diatomaceous earth.

[0039] The inorganic fertilizers included superphosphate, monoammonium phosphate, chelated iron, potassium sulfate, chelated zinc, and sodium octaborate tetrahydrate in a mass ratio of 1:0.5:0.1:0.5:0.08:0.08; the organic fertilizers were bone meal and grape pomace in a mass ratio of 1:1; and the modified humic acid was prepared from Preparation Example 1.

[0040] The preparation method of peat water-retaining fertilizer includes the following steps: (1) The organic fertilizer is decomposed and then mixed with the inorganic fertilizer, granulated and dried to obtain a compound solid fertilizer; (2) The compound solid fertilizer is mixed with modified humic acid, acrylic acid-acrylamide gel and diatomaceous earth, and swelled in a large particle urea aqueous solution. Then the compound solid fertilizer in step (1) is added and granulated in a granulator (the disc tilt angle is set to 38° and the rotation speed is set to 50r / min). After air drying, it is mixed with peat to obtain peat water-retaining fertilizer.

[0041] Example 2 A peat water-retaining fertilizer comprises the following raw materials in parts by weight: 700 parts of 44wt% granular urea aqueous solution, 60 parts of peat, 40 parts of inorganic fertilizer, 25 parts of organic fertilizer, 5 parts of modified humic acid, 2 parts of acrylic acid-acrylamide gel, and 5 parts of diatomaceous earth.

[0042] The inorganic fertilizers included superphosphate, monoammonium phosphate, chelated iron, potassium sulfate, chelated zinc, and sodium octaborate tetrahydrate in a mass ratio of 1:0.4:0.08:0.4:0.06:0.06; the organic fertilizers were bone meal and grape pomace in a mass ratio of 1:1; and the modified humic acid was prepared from Preparation Example 1.

[0043] The preparation method of peat water-retaining fertilizer includes the following steps: (1) The organic fertilizer is decomposed and then mixed with the inorganic fertilizer, granulated and dried to obtain a compound solid fertilizer; (2) The compound solid fertilizer is mixed with modified humic acid, acrylic acid-acrylamide gel and diatomaceous earth, and swelled in a large particle urea aqueous solution. Then the compound solid fertilizer in step (1) is added and granulated in a granulator (the disc tilt angle is set to 38° and the rotation speed is set to 50r / min). After air drying, it is mixed with peat to obtain peat water-retaining fertilizer.

[0044] Example 3 A peat water-retaining fertilizer comprises the following raw materials in parts by weight: 900 parts of 46wt% granular urea aqueous solution, 100 parts of peat, 50 parts of inorganic fertilizer, 35 parts of organic fertilizer, 10 parts of modified humic acid, 8 parts of acrylic acid-acrylamide gel, and 10 parts of diatomaceous earth.

[0045] The inorganic fertilizers included superphosphate, monoammonium phosphate, chelated iron, potassium sulfate, chelated zinc, and sodium octaborate tetrahydrate in a mass ratio of 1:0.6:0.15:0.6:0.1:0.1; the organic fertilizers were bone meal and grape pomace in a mass ratio of 1:1; and the modified humic acid was prepared from Preparation Example 1.

[0046] The preparation method of peat water-retaining fertilizer includes the following steps: (1) The organic fertilizer is decomposed and then mixed with the inorganic fertilizer, granulated and dried to obtain a compound solid fertilizer; (2) The compound solid fertilizer is mixed with modified humic acid, acrylic acid-acrylamide gel and diatomaceous earth, and swelled in a large particle urea aqueous solution. Then the compound solid fertilizer in step (1) is added and granulated in a granulator (the disc tilt angle is set to 38° and the rotation speed is set to 50r / min). After air drying, it is mixed with peat to obtain peat water-retaining fertilizer.

[0047] Example 4 A peat water-retaining fertilizer and its preparation method are described. The specific implementation method is the same as in Example 1, except that the modified humic acid is prepared in Example 2.

[0048] Example 5 A peat water-retaining fertilizer and its preparation method are described. The specific implementation method is the same as in Example 1, except that the modified humic acid is prepared in Example 3.

[0049] Example 6 A peat water-retaining fertilizer and its preparation method are described. The specific implementation method is the same as in Example 1, except that the modified humic acid is prepared in Example 4.

[0050] Comparative Example 1 Comparative Example 2 A peat water-retaining fertilizer and its preparation method are described. The specific implementation method is the same as in Example 1, except that humic acid of equal mass is used instead of modified humic acid.

[0051] Performance testing; (1) An experiment was conducted in a field in Dazeshan Town, Pingdu City, Chengyang District, Qingdao, Shandong Province. The experimental subjects were grape seedlings. Before sowing, the average soil moisture content at a depth of 10 cm was measured for each treatment. After harvest, the average soil moisture content at a depth of 10 cm was measured for each treatment. During the experiment, each experimental group was applied with peat water-retaining fertilizer prepared in Examples 1-6 and Comparative Example 1 of this application, at a rate of 65 kg / mu. The results are shown in Table 1.

[0052] Table 1

[0053] According to the data in Table 1, the peat water-retaining fertilizers prepared in Examples 1-4 of this application have good water retention capacity; in Example 5, the water retention capacity of the peat water-retaining fertilizer decreased due to the reduction of acrylic acid caused by the change in the mass ratio of pretreated humic acid to acrylic acid; in Example 6, the water retention capacity of the peat water-retaining fertilizer decreased due to the change in the mass ratio of polyacrylic acid modified humic acid complex to trehalose; and in Comparative Example 1, the water retention capacity of the peat water-retaining fertilizer decreased due to the use of an equal mass of humic acid instead of modified humic acid.

[0054] (2) Seven corn experimental fields with severe heavy metal pollution (average lead content of 284.7 mg / kg) were selected and peat water-retaining fertilizers of Examples 1-6 and Comparative Example 1 were applied at a rate of 60 kg / mu. The lead content in the soil was tested after 30 days. The test results are shown in Table 2.

[0055] Table 2

[0056] According to the data in Table 2, the peat water-retaining fertilizers prepared in Examples 1-3 of this application can effectively reduce the heavy metal content in the soil. In Example 4, the mass ratio of pretreated humic acid to acrylic acid was changed, and the increase in acrylic acid led to a decrease in the cross-linking content of trehalose, thus weakening the adsorption capacity for heavy metals. In Example 5, the mass ratio of pretreated humic acid to acrylic acid was changed, and the decrease in acrylic acid reduced the cross-linking network structure, thus weakening the adsorption capacity for heavy metals. In Example 6, the mass ratio of polyacrylic acid modified humic acid complex to trehalose was changed, resulting in a weakening of the heavy metal adsorption capacity of the peat water-retaining fertilizer. In Comparative Example 1, the use of an equal mass of humic acid instead of modified humic acid resulted in a weakening of the heavy metal adsorption capacity of the peat water-retaining fertilizer.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A peat-based water-retaining fertilizer, characterized in that, The raw materials include the following parts by weight: 700-900 parts of large-particle urea aqueous solution with a concentration of 44-46wt%, 60-100 parts of peat, 40-50 parts of inorganic fertilizer, 25-35 parts of organic fertilizer, 5-10 parts of modified humic acid, 2-8 parts of water-retaining gel, and 5-10 parts of filler.

2. The peat water-retaining fertilizer according to claim 1, characterized in that, The inorganic fertilizer is a mixture of superphosphate, monoammonium phosphate, chelated iron, potassium sulfate, chelated zinc and sodium octaborate tetrahydrate.

3. The peat water-retaining fertilizer according to claim 1, characterized in that, The organic fertilizer is one or more of rapeseed cake powder, bone meal, mushroom residue, and grape residue.

4. The peat water-retaining fertilizer according to claim 1, characterized in that, The method for preparing the modified humic acid includes the following steps: A1. Mix humic acid with 13-16 wt% dilute sulfuric acid, heat to 45-55℃ and stir for 3-4 hours, then dry under reduced pressure to obtain pretreated humic acid. A2. Under an inert protective gas atmosphere, the pretreated humic acid from step A1 is mixed with acrylic acid and added to toluene. An initiator is added, and the mixture is heated to 65~75℃ and stirred at a constant temperature for 5~6 hours. After the mixture is heated, it is concentrated under reduced pressure and dried to obtain a polyacrylic acid modified humic acid composite. A3. Under an inert protective gas atmosphere, the polyacrylic acid modified humic acid complex from step A2 is mixed with trehalose, and the mixture is heated and stirred to obtain modified humic acid.

5. The peat water-retaining fertilizer according to claim 4, characterized in that, In step A2, the mass ratio of pretreated humic acid to acrylic acid is 1:(1~1.4).

6. The peat water-retaining fertilizer according to claim 4, characterized in that, In step A3, the mass ratio of polyacrylic acid modified humic acid complex to trehalose is 1:(0.9~1.2).

7. The peat water-retaining fertilizer according to claim 4, characterized in that, In step A3, the temperature rise rate is 2~4℃ / min, the temperature is 170~190℃, and the stirring time is 50~60min.

8. The peat water-retaining fertilizer according to claim 1, characterized in that, The water-retaining gel is an acrylic-acrylamide gel.

9. The peat water-retaining fertilizer according to claim 1, characterized in that, The filler is any one or more of diatomaceous earth, attapulgite, and bentonite.

10. A method for preparing peat water-retaining fertilizer according to any one of claims 1 to 9, characterized in that, Includes the following steps: (1) The organic fertilizer is decomposed and then mixed with the inorganic fertilizer, granulated and dried to obtain a compound solid fertilizer; (2) The composite solid fertilizer is mixed with modified humic acid, water-retaining gel and filler, and then swollen in a large particle urea aqueous solution. Then the composite solid fertilizer in step (1) is added and granulated in a granulator. After air drying, it is mixed with peat to obtain peat water-retaining fertilizer.

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