Farmland drought-resisting, water-retaining and fertilizing multifunctional fertilizer and preparation method thereof

Abstract

The invention relates to the field of agricultural fertilizers, in particular to a farmland drought-resisting, water-retaining and fertilizing multifunctional fertilizer and a preparation method thereof. The multifunctional fertilizer is prepared from the following components in parts by weight: 2 to 6 parts of starch grafted acrylic acid SAP, 1 to 4 parts of cyclopentanone, 2 to 6 parts of enzymolysis brown algae extract, 1 to 4 parts of straw carbon, 1 to 4 parts of polyglutamic acid, 1 to 4 parts of betaine, 2 to 6 parts of polyacrylamide, 6 to 12 parts of humic acid, 40 to 50 parts of organic fertilizer, 15 to 25 parts of NPK chemical fertilizer and 5 to 10 parts of bentonite. Wherein the organic fertilizer is prepared by fermenting 70% of chicken manure, 20% of pig manure and 10% of straw powder. The fertilizer can reduce soil hardening, improve porosity, enhance air permeability and reduce water and soil loss caused by rain wash, and humic acid is a carbon source of soil microorganisms and can stimulate reproduction of beneficial microorganisms (such as nitrogen-fixing bacteria and phosphate solubilizing bacteria), accelerate decomposition of organic matters and release more effective nutrients.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural fertilizers, in particular to a multifunctional fertilizer for drought resistance, water conservation and fertilizer cultivation in farmland and a preparation method thereof. BACKGROUND

[0002] In agricultural production, water and nutrients are key factors affecting the growth and development of crops, and play a decisive role in the yield and quality of crops. However, current agricultural production faces many severe challenges. On the one hand, water resource shortage is becoming increasingly serious. Droughts occur frequently and widely, seriously restricting the growth and yield of crops. China is a large agricultural country, and precipitation is unevenly distributed in some areas, with drought disasters occurring from time to time, causing great losses to agricultural production. According to relevant data, in 2020, the drought in Fuxin, Liaoning Province, caused the crop disaster area to reach more than 2 million mu, with a yield reduction rate of more than 30%. At the same time, the efficiency of agricultural water use is low, and traditional irrigation methods such as flooding irrigation and ditch irrigation cause a large amount of waste of water resources, further exacerbating the tense situation of water resources; on the other hand, the problem of soil fertility decline cannot be ignored. Long-term unreasonable fertilization, excessive tillage and water and soil loss, etc. factors, leading to soil structure damage, soil organic matter content reduction, soil water and fertilizer conservation capacity weakening, soil serious hardening, aeration and permeability deterioration, affecting the growth of crop root system and nutrient absorption.

[0003] To cope with these problems, multifunctional fertilizers have emerged as the times require. In recent years, multifunctional fertilizers have received widespread attention and development worldwide. In China, with the implementation of a series of fertilizer reduction and efficiency projects, zero growth of fertilizer use and green planting and breeding circular agriculture pilot, the multifunctional fertilizer industry has developed rapidly. However, the existing multifunctional fertilizers still have many shortcomings. The cost of some multifunctional fertilizers is too high, such as some products containing special synergists or using complex preparation process, the price is often several times that of ordinary fertilizers, limiting their widespread application in large-scale agricultural production, especially in the planting of field crops; in terms of function synergy, although many multifunctional fertilizers claim to have multiple functions, in actual application, the functions may interfere with each other, and the synergistic effect cannot be fully played, making it difficult to truly meet the complex needs of crops for water and nutrients at different growth stages. Moreover, the adaptability of some multifunctional fertilizers in different soil conditions is poor, and their water conservation, fertilizer cultivation and other functions are greatly discounted in special soil environments such as saline-alkali soil and acid soil. As an important component of multifunctional fertilizers, water-retaining agents also have many defects, such as high cost of some water-retaining agents, limiting their large-scale application; poor salt tolerance of some water-retaining agents, greatly reducing the water retention effect in saline-alkali soil; and weak degradability of some water-retaining agents, which may cause potential harm to the soil environment in the long term.

[0004] Traditional fertilizers (pure inorganic fertilizer, simple compound fertilizer) have obvious defects, such as inorganic fertilizer, which is easy to leach (nitrogen loss), fixed (phosphorus is fixed by iron and aluminum ions) to cause low utilization rate, and long-term use aggravates soil acidification and hardening; and the nutrients of organic fertilizer are released slowly, which is difficult to meet the demand of crop rapid growth period, and the cost is high, and the short-term yield increasing effect is not obvious; the core defects of traditional fertilizer are "single function" and "ecological unfriendly": inorganic fertilizer pursues quick-acting but destroys soil, organic fertilizer focuses on soil improvement but fertilizer supply is lagging, and compound fertilizer does not realize multi-dimensional cooperation; which directly leads to the problems of "increasing yield but not increasing income" (high cost), "fertilizer injury" (soil degradation), "weak resistance" and the like in agricultural production, and it is urgent to break through the traditional limitation through new multi-functional fertilizer technology, so as to ensure the water and fertilizer cooperation of soil and the efficient growth of crops under drought conditions.

[0005] In summary, it is urgent to develop a multifunctional fertilizer which can effectively resist drought and retain water, improve soil fertility, improve fertilizer utilization rate and is environment-friendly. The present application aims to provide a farmland drought-resistant water-retaining and soil-fertilizing multifunctional fertilizer and a preparation method thereof, to solve the above problems in existing agricultural production and promote the sustainable development of agriculture. SUMMARY

[0006] To solve the above problems, the present application provides a farmland drought-resistant water-retaining and soil-fertilizing multifunctional fertilizer and a preparation method thereof, which is used to solve the problem of single function of traditional fertilizer, and the multifunctional fertilizer with drought-resistant water-retaining effect, making agricultural fertilization more convenient.

[0007] In order to achieve the above purpose, the technical scheme of the present application is as follows: a farmland drought-resistant water-retaining and soil-fertilizing multifunctional fertilizer, comprising the following components by weight: starch grafting acrylic acid SAP 2-6 parts, cyclopentanone 1-4 parts, enzyme-degraded brown algae extract 2-6 parts, straw carbon 1-4 parts, polyglutamic acid 1-4 parts, betaine 1-4 parts, polyacrylamide 52-106 parts, humic acid 106-1215 parts, organic fertilizer 40-50 parts, NPK fertilizer 15-25 parts and bentonite 5-10 parts, wherein the organic fertilizer is obtained by fermentation of chicken manure 70%, pig manure 20% and straw powder 10%.

[0008] Further, it comprises the following components by weight: starch grafting acrylic acid SAP 2 parts, cyclopentanone 1 part, enzyme-degraded brown algae extract 2 parts, straw carbon 1 part, polyglutamic acid 1 part, betaine 1 part, polyacrylamide 2 parts, humic acid 6 parts, organic fertilizer 40 parts, NPK fertilizer 15 parts and bentonite 5 parts.

[0009] Further, it comprises the following components by weight parts: starch grafting acrylic acid SAP 4 parts, cyclopentanone 3 parts, enzymatic brown algae extract 3 parts, straw charcoal 2 parts, polyglutamic acid 2 parts, betaine 2 parts, polyacrylamide 4 parts, humic acid 8 parts, organic fertilizer 45 parts, NPK chemical fertilizer 20 parts and bentonite 8 parts.

[0010] Further, it comprises the following components by weight parts: starch grafting acrylic acid SAP 6 parts, cyclopentanone 4 parts, enzymatic brown algae extract 6 parts, straw charcoal 4 parts, polyglutamic acid 4 parts, betaine 4 parts, polyacrylamide 6 parts, humic acid 12 parts, organic fertilizer 50 parts, NPK chemical fertilizer 25 parts and bentonite 10 parts.

[0011] Further, a method for preparing a multifunctional fertilizer for drought resistance, water conservation and soil fertilization in farmland, the preparation steps are as follows: Step one, raw material pretreatment: first, the organic fertilizer is composted and fermented for 30 days, and the compost is turned over 3 times during the process, then the compost is dried to a moisture content of less than 30%, and the compost is mixed with straw charcoal in proportion, finally the mixed straw charcoal and compost are crushed to pass through a 20 mesh screen; Mix NPK chemical fertilizer and cyclopentanone in proportion, then crush to pass through a 40 mesh screen, so that the particle diameter is ≤0.42mm; Crush polyacrylamide powder and starch grafting acrylic acid to 80 mesh, the particle diameter is ≤0.18mm, then spray treatment with 20% NaCl solution, wherein water:NaCl=4:1; Mix humic acid with KOH in a ratio of 10:1 to activate, dry and crush to 60-80 mesh after aging for 24 hours; Sodium modification of bentonite, add 4% Na2CO3 to bentonite, then dry to a moisture content of ≤8%, finally crush to pass through a 60 mesh screen; Step two, core layer granulation: put the treated organic fertilizer into a double screw extrusion granulator for granulation treatment to form organic fertilizer particles as the core layer of the fertilizer; Step three, intermediate layer coating: put the organic fertilizer particles into the pretreated NPK fertilizer particles for intermediate layer coating to form the base fertilizer; Step four, preparation of bonding solution: prepare 60 parts of 15% fulvic acid solution, 5 parts of powder seaweed extract, 2 parts of betaine, 3 parts of polyvinyl alcohol and 30 parts of water, dissolve polyvinyl alcohol in a 60℃ water bath, after cooling to 40℃, add fulvic acid solution, powder seaweed extract, enzymatic brown algae extract, polyglutamic acid, betaine and water, filter to form the bonding solution for standby; Step five, mixing of wrapping layer: mix the pretreated polyacrylamide, starch grafting acrylic acid, humic acid and bentonite uniformly to form the wrapping layer; Step six, the wrapping layer coating: evenly wrap the base fertilizer surface with the adhesive liquid, then put into the wrapping layer for coating, forming the fertilizer semi-finished product; Step seven, low-temperature drying: put the fertilizer semi-finished product into the drying machine for low-temperature drying; Step eight, vacuum impregnation: after low-temperature drying, the fertilizer semi-finished product is vacuumed to-0.08MPa for 20 minutes, then soaked with the impregnation liquid under normal pressure for 30 minutes, drained and then dried for the second time; Step nine, microbial coating: the vacuum-impregnated fertilizer semi-finished product is coated with microbes using the fluidized bed bottom spraying technology, the inlet air temperature is controlled at 35℃, after coating, 2% CaCl2 solution is used for spraying cross-linking and solidification; Step ten, screening and packaging: the microbial coating treatment completed fertilizer semi-finished product is screened and then packaged to obtain the fertilizer finished product multifunctional fertilizer.

[0012] Further, in the step six, the adhesive liquid is sprayed, the spraying pressure is 0.8MPa, the atomized particle size is 50-80μm, and the adhesive liquid addition amount is 8-10% of the total weight of the material.

[0013] Further, in the step seven, the low-temperature drying uses the countercurrent rotary dryer, the inlet air temperature is≤80℃, and the drying is performed until the moisture content of the particles is≤8%.

[0014] Further, in the step eight, the impregnation liquid is composed of 3% abscisic acid, 2% potassium silicate and 30% ethanol solution.

[0015] Further, in the step ten, the vibration screen is used to separate the qualified particles of 2-4mm, the oversize material≥4mm is returned to the granulator for regrinding, and the undersize material≤2mm is returned to the intermediate layer coating process.

[0016] Further, in the step nine, the coating liquid used for coating is mixed by 3% sodium alginate solution 70 parts, 50 billion CFU / g Bacillus subtilis suspension 20 parts and 2% chitosan acetic acid solution 10 parts.

[0017] The effects of each component used in the application are as follows: Polyacrylamide: 1. Water retention and drought resistance: Polyacrylamide is a high molecular polymer with strong water absorption and water retention, which can absorb hundreds of times of water of its own weight, form "hydrogel" to wrap soil particles, reduce water evaporation and leakage, prolong water supply time and relieve drought stress.

[0018] 2. Improve soil structure: Polyacrylamide can promote the formation of soil aggregate structure, reduce soil hardening, improve porosity, and enhance air permeability, while reducing water and soil loss caused by rainwater erosion.

[0019] Humic acid: 1. Activates soil nutrients: Humic acid contains active groups such as carboxyl and phenolic hydroxyl groups, which can complex with metal ions such as calcium, magnesium, and iron in the soil, reducing the fixation of nutrients such as phosphorus and potassium (e.g., preventing the formation of insoluble phosphates), and improving fertilizer utilization.

[0020] 2. Promotes microbial activity: Humic acid is a carbon source for soil microorganisms, stimulating the reproduction of beneficial microorganisms (such as nitrogen-fixing bacteria and phosphorus-solubilizing bacteria), accelerating the decomposition of organic matter, and releasing more available nutrients.

[0021] 3. Enhances plant stress resistance: Humic acid can improve plant cell membrane stability, promote root development, and enhance the tolerance to drought, salinity, and other adverse conditions.

[0022] Organic fertilizer: 1. Provides long-term nutrients: Organic fertilizer contains rich organic matter (such as cellulose and protein) and trace elements (such as calcium, magnesium, and sulfur), which are slowly released by microbial decomposition (such as nitrogen, phosphorus, and potassium) to meet the needs of plants throughout their growth period.

[0023] 2. Improves soil texture: Humic substances in organic fertilizer can increase soil organic matter content, improve soil aggregate structure, and enhance water and nutrient retention capacity (such as increasing cation exchange capacity, adsorbing ammonium nitrogen, and potassium ions).

[0024] 3. Inhibits soil-borne diseases: Fermented organic fertilizer contains antagonistic microorganisms (such as Bacillus subtilis), which can inhibit the reproduction of pathogenic fungi (such as Fusarium and Rhizoctonia solani) and reduce the risk of soil-borne diseases.

[0025] NPK chemical fertilizer: 1. Rapidly available nutrients: Urea (nitrogen source), ammonium phosphate (phosphorus source), and potassium chloride (potassium source) provide essential macronutrients (N, P, K) for plants, meeting the rapid nutrient demand during key growth stages such as seedling and flowering, avoiding growth retardation or yield reduction due to nutrient deficiency.

[0026] 2. Balanced nutrition: Precise proportioning of N, P, and K (such as high-nitrogen for leaves, high-phosphorus for flowers, and high-potassium for fruits) coordinates plant vegetative growth and reproductive growth, improving yield and quality.

[0027] Bentonite: 1. Enhances water and nutrient retention: Sodium-modified bentonite has an expansion capacity of ≥8 mL / g (unmodified bentonite has an expansion capacity of about 3-5 mL / g), and after absorbing water, it forms a "sponge-like" structure that adsorbs water and nutrients (such as ammonium ions and potassium ions), reducing leaching.

[0028] 2. Adjusts soil pH: Sodium-based bentonite is weakly alkaline, which can neutralize H⁺ in acidic soils (such as red soil), alleviating acid damage; at the same time, its interlayer structure can exchange harmful ions (such as aluminum ions) in the soil, reducing toxicity.

[0029] The above scheme realizes the following beneficial effects: 1. "Water retention-water supply" dual effect enhancement: polyacrylamide rapid water absorption and bentonite slow water release cooperate to form a "short-term water locking + long-term water supply" water regulation system, the water supply time is extended by 20%-30% during drought period; at the same time, organic fertilizer and humic acid improve soil structure, reduce water evaporation, and further improve drought resistance.

[0030] 2. "Quick- and slow-acting" nutrient complementation: NPK fertilizer provides quick-acting nutrients (2-7 days for effect), meeting the early needs of plants; organic fertilizer and humic acid slowly release nutrients (15-30 days for sustained fertilizer supply) through microbial decomposition, avoiding the problems of "early seedling burning and late fertilizer loss", and increasing nutrient utilization rate by 15%-20%.

[0031] 3. "Soil improvement-bacterium inhibition" dual protection: humic acid and organic fertilizer increase soil organic matter (target increase of 1-2 g / kg), promoting the formation of granular structure; bentonite adsorbs heavy metals and pathogenic bacteria, combined with antagonistic microorganisms in organic fertilizer, the incidence of soil-borne diseases is reduced by 30%-40%.

[0032] 4. "Stress resistance-yield increase" comprehensive improvement: humic acid and polyacrylamide enhance plant drought resistance (leaf wilting rate reduced by 25%), NPK and organic fertilizer ensure nutrient supply (crop yield increased by 10%-15%), ultimately achieving the multifunctional goal of "drought resistance without yield reduction and sustainable soil fertility improvement".

[0033] 5. Layered coating (core layer→middle layer→wrapping layer) is the core innovation of the preparation method, through the spatial distribution optimization of multi-component functional layers, the precise regulation of nutrient release and water retention performance is realized: · Core layer (organic fertilizer particles): The double-screw extrusion granulator makes the pretreated organic fertilizer into core particles (particle size 2-4 mm), which utilizes the "porous structure + viscosity" characteristics of organic fertilizer to provide stable physical support for the middle layer and the wrapping layer, and continuously releases organic matter and trace elements (such as calcium, magnesium, sulfur) through slow decomposition, meeting the long-term nutrient needs of crops during the whole growth period, and field tests show that the addition of straw carbon increases soil organic matter by 133%, and cooperates with bentonite to form a "sponge-granular" composite structure.

[0034] · Middle layer (NPK fertilizer coating): NPK fertilizer particles are evenly coated on the surface of the organic fertilizer core to form a "quick-acting nutrient layer". NPK (urea, ammonium phosphate, potassium chloride) as a soluble component, can be released quickly within 1-2 weeks after fertilization (accounting for 30%-40% of the total nutrient content), meeting the "urgent nutrient demand" of crops during the critical stages of seedling and flowering, and avoiding growth retardation due to nutrient deficiency.

[0035] · Wrapping layer (polyacrylamide + humic acid + bentonite mixed coating): The pretreated polyacrylamide (water retention), humic acid (activation promotion) and bentonite (fertilizer retention) are closely attached to the surface of the intermediate layer through the adhesive liquid (fulvic acid + seaweed extract + polyvinyl alcohol) to form a "slow-release water-retention composite layer", and the addition of seaweed extract can improve the adhesion of the coating layer, and the polyglutamic acid can form an interpenetrating network with the polysaccharides of seaweed extract to enhance the toughness of the coating layer: The water absorption of polyacrylamide forms a "hydrogel", reducing water evaporation and leakage (water retention capacity improved by more than 50%), and the addition of starch grafted acrylic acid SAP and bentonite can form a "fast water absorption-slow water release" system, polyacrylamide is responsible for short-term water locking, starch-based SAP provides continuous water supply through the reticular structure, and improves drought resistance; meanwhile, humic acid can enhance its salt tolerance (carboxyl groups chelate metal ions); Humic acid complexed nutrients, delaying the dissolution rate of NPK (long-term release period extended to 80-100 days); Bentonite adsorbs ammonium and potassium ions, reducing leaching (increasing nutrient utilization rate by 20%-30%).

[0036] Additional aspects and advantages of the application will be described in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The process flow chart of the preparation method of the farmland drought-resistant water-retention and fertilizer-enriching multifunctional fertilizer of the application. DETAILED DESCRIPTION

[0038] The technical solutions of the application will be described clearly and completely below with reference to the drawings, obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0039] In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0040] In the description of the present application, it should be noted that unless otherwise expressly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] Further details are described below through specific embodiments: Example 1:

[0042] A farmland drought-resistant water-retaining and fertilizing multifunctional fertilizer, comprising the following components in parts by weight: starch grafting acrylic acid SAP 2-6 parts, cyclopentanone 1-4 parts, enzymatic brown algae extract 2-6 parts, straw carbon 1-4 parts, polyglutamic acid 1-4 parts, betaine 1-4 parts, polyacrylamide 2-6 parts, humic acid 6-12 parts, organic fertilizer 40-50 parts, NPK chemical fertilizer 15-25 parts and bentonite 5-10 parts, wherein the organic fertilizer is made by fermentation of chicken manure 70%, pig manure 20% and straw powder 10%.

[0043] Example 2:

[0044] The difference from the above-mentioned embodiments is that the farmland drought-resistant water-retaining and fertilizing multifunctional fertilizer comprises the following components in parts by weight: starch grafting acrylic acid SAP 2 parts, cyclopentanone 1 part, enzymatic brown algae extract 2 parts, straw carbon 1 part, polyglutamic acid 1 part, betaine 1 part, polyacrylamide 2 parts, humic acid 6 parts, organic fertilizer 40 parts, NPK chemical fertilizer 15 parts and bentonite 5 parts.

[0045] Example 3:

[0046] The difference from the above-mentioned embodiments is that the farmland drought-resistant water-retaining and fertilizing multifunctional fertilizer comprises the following components in parts by weight: starch grafting acrylic acid SAP 4 parts, cyclopentanone 3 parts, enzymatic brown algae extract 3 parts, straw carbon 2 parts, polyglutamic acid 2 parts, betaine 2 parts, polyacrylamide 4 parts, humic acid 8 parts, organic fertilizer 45 parts, NPK chemical fertilizer 20 parts and bentonite 8 parts.

[0047] Example 4:

[0048] The difference from the above-mentioned embodiments is that the farmland drought-resistant water-retaining and fertilizing multifunctional fertilizer comprises the following components in parts by weight: starch grafting acrylic acid SAP 6 parts, cyclopentanone 4 parts, enzymatic brown algae extract 6 parts, straw carbon 4 parts, polyglutamic acid 4 parts, betaine 4 parts, polyacrylamide 6 parts, humic acid 12 parts, organic fertilizer 50 parts, NPK chemical fertilizer 25 parts and bentonite 10 parts.

[0049] Example 5:

[0050] The difference from the above examples is that, as shown in the accompanying drawings, a method for preparing a multifunctional fertilizer for drought resistance, water conservation and soil fertilization in farmland, the preparation steps are as follows: Figure 1 Step 1, raw material pretreatment: first, the organic fertilizer is fermented for 30 days, and the pile is turned over 3 times during the process, then the compost is dried to a moisture content of less than 30%, and the compost is mixed with straw charcoal in proportion, and finally the mixed straw charcoal and compost are crushed to pass through a 20 mesh screen; Mix NPK fertilizer and cyclopentanone in proportion, then crush to pass through a 40 mesh screen, so that the particle diameter is ≤0.42mm; Crush polyacrylamide and starch grafted acrylic acid to 80 mesh, the particle diameter is ≤0.18mm, then spray with 20% NaCl solution, the ratio of water to NaCl is 4:1; Mix humic acid with KOH at a ratio of 10:1 to activate, dry and crush to 60-80 mesh after aging for 24 hours; Sodium modification of bentonite, add 4% Na2CO3 to bentonite, then dry to a moisture content of ≤8%, and finally crush to pass through a 60 mesh screen; Step 2, core layer granulation: put the treated organic fertilizer into a double screw extrusion granulator for granulation treatment to form organic fertilizer particles as the core layer of the fertilizer; Step 3, intermediate layer coating: put the organic fertilizer particles into the pretreated NPK fertilizer particles for intermediate layer coating to form the base fertilizer; Step 4, preparation of bonding solution: prepare 60 parts of 15% fulvic acid solution, 5 parts of powder seaweed extract, 2 parts of betaine, 3 parts of polyvinyl alcohol and 30 parts of water, dissolve polyvinyl alcohol in a 60℃ water bath, cool to 40℃, then add fulvic acid solution, powder seaweed extract, enzymatic brown algae extract, polyglutamic acid, betaine and water, filter to form the bonding solution for standby; Step 5, mixing of wrapping layer: mix the pretreated polyacrylamide, starch grafted acrylic acid, humic acid and bentonite uniformly to form the wrapping layer; Step 6, wrapping layer coating: evenly coat the bonding solution on the surface of the base fertilizer, then put it into the wrapping layer for coating to form the fertilizer semi-finished product, wherein the bonding solution is sprayed, the spraying pressure is 0.8MPa, the atomized particle size is 50-80μm, and the amount of bonding solution added is 8-10% of the total weight of the material; Step 7, low temperature drying: put the fertilizer semi-finished product into a drying machine for low temperature drying, the low temperature drying uses a countercurrent rotary dryer, the inlet air temperature is ≤80℃, and the drying is carried out until the moisture content of the particles is ≤8%; Step 7, low temperature drying: put the fertilizer semi-finished product into a drying machine for low temperature drying, the low temperature drying uses a countercurrent rotary dryer, the inlet air temperature is ≤80℃, and the drying is carried out until the moisture content of the particles is ≤8%; Step eight, vacuum impregnation: after low-temperature drying, the fertilizer semi-finished product is vacuumed to-0.08 MPa for 20 minutes, then soaked in the impregnating solution under normal pressure for 30 minutes, drained and dried again, the impregnating solution is composed of 3% abscisic acid, 2% potassium silicate and 30% ethanol solution; Step nine, microbial coating: the vacuum-impregnated fertilizer semi-finished product is coated with microorganisms using fluidized bed bottom spraying technology, the inlet air temperature is controlled at 35℃, after coating, 2% CaCl2 solution is sprayed for cross-linking and solidification; the coating solution used for coating is mixed by 3% sodium alginate solution 70 parts, 50 billion CFU / g Bacillus subtilis suspension 20 parts and 2% chitosan acetic acid solution 10 parts; Step ten, screening and packaging: the microbial coating treatment completed fertilizer semi-finished product is screened, the qualified particles of 2-4 mm are separated by vibration screening, the oversize material ≥4 mm is returned to the granulator for re-pulverization, and the undersize material ≤2 mm is returned to the middle layer coating process; then the multifunctional fertilizer product is obtained by packaging, the packaging adopts moisture-proof woven bag, lined with PE film, each bag is 50 kg, and is labeled with "drought-resistant water-retaining and fertilizing multifunctional fertilizer" and ingredient ratio.

[0051] The weight parts of the raw materials in the examples are selected according to any one of examples 1-4.

[0052] The roles of each component used in the application are as follows: Polyacrylamide: 1. Water retention and drought resistance: Polyacrylamide is a high molecular polymer with strong water absorption and water retention, it can absorb hundreds of times its own weight of water, form a "hydrogel" to wrap soil particles, reduce water evaporation and leakage, prolong water supply time, and alleviate drought stress.

[0053] 2. Improve soil structure: Polyacrylamide can promote the formation of soil aggregate structure, reduce soil hardening, improve porosity, and enhance air permeability, while reducing soil erosion caused by rainwater erosion.

[0054] Humic acid: 1. Activating soil nutrients: Humic acid contains active groups such as carboxyl and phenolic hydroxyl groups, which can complex with metal ions such as calcium, magnesium and iron in the soil, reduce the fixation of nutrients such as phosphorus and potassium (such as avoiding the combination of phosphorus and calcium to form insoluble phosphate), and improve the utilization rate of fertilizer.

[0055] 2. Promote microbial activity: Humic acid is a carbon source for soil microorganisms, which can stimulate the reproduction of beneficial microorganisms (such as nitrogen-fixing bacteria and phosphorus-solubilizing bacteria), accelerate the decomposition of organic matter, and release more available nutrients.

[0056] 3. Enhance plant stress resistance: Humic acid can improve the stability of plant cell membrane, promote root development, and enhance the tolerance to drought, salinity and other adverse conditions.

[0057] Organic fertilizer: 1. Provide long-term nutrients: Organic fertilizer contains rich organic matter (such as cellulose, protein) and trace elements (calcium, magnesium, sulfur, etc.), which slowly release nutrients (such as nitrogen, phosphorus, potassium) through microbial decomposition, meeting the needs of plant growth throughout the life cycle. Among them, chicken manure contains 25.5% organic matter, 1.63% nitrogen, 1.54% phosphorus and 0.85% potassium, which is significantly higher than other livestock and poultry manure, equivalent to 5-6 times of cow manure, which can quickly supplement soil nutrients; At the same time, the organic matter in pig manure is 15.0%, the nitrogen is 0.60%, the phosphorus is 0.40%, the potassium is 0.44%, the carbon-nitrogen ratio is low (14:1), the decomposition is fast and the fertilizer effect is durable, It has the characteristics of "warm fertilizer", which can improve sandy soil and clay soil; And, mixed fermentation can reduce the high salt risk of chicken manure, while taking advantage of the balanced nutrients of pig manure and the organic matter of straw to improve the synergistic effect of fertilizer water retention and fertilization.

[0058] 2. Improve soil texture: Humic substances in organic fertilizer can increase soil organic matter content, improve soil aggregate structure, and improve water and fertilizer retention capacity (such as increase cation exchange capacity, adsorb ammonium nitrogen, potassium ions, etc.).

[0059] 3. Inhibit soil-borne diseases: Fermented organic fertilizer contains antagonistic microorganisms (such as Bacillus subtilis), which can inhibit the reproduction of pathogenic bacteria (such as Fusarium, Rhizoctonia solani) and reduce the risk of soil-borne diseases.

[0060] NPK chemical fertilizer: 1. Rapid available fertilizer: Urea (nitrogen source), ammonium phosphate (phosphorus source), potassium chloride (potassium source) provide essential macronutrients (N, P, K) for plants, meeting the rapid nutrient demand of key growth stages such as seedling stage and flowering stage, and avoiding growth retardation or yield reduction due to nutrient deficiency.

[0061] 2. Balanced nutrition: By accurately matching N, P, K (such as high nitrogen to promote leaves, high phosphorus to promote flowers, and high potassium to promote fruits), the plant's vegetative growth and reproductive growth are coordinated, and the yield and quality are improved.

[0062] Bentonite: 1. Enhance water and fertilizer retention: The swelling capacity of sodium-modified bentonite is ≥8 mL / g (the swelling capacity of unmodified bentonite is about 3-5 mL / g), and the volume expands after water absorption, forming a "sponge-like" structure, adsorbing water and nutrients (such as ammonium ions and potassium ions), and reducing leaching.

[0063] 2. Adjust soil pH: Sodium-based bentonite is weakly alkaline, which can neutralize H⁺ in acidic soil (such as red soil) and alleviate acid damage; At the same time, its interlayer structure can exchange harmful ions (such as aluminum ions) in the soil, reducing toxicity.

[0064] Based on the above-mentioned multifunctional fertilizer for farmland drought resistance, water retention and fertilization and its preparation method, the following tests are carried out: Experiment one Purpose of the experiment: Verify the effect of the formula multifunctional fertilizer in drought resistance, water retention and soil fertility.

[0065] Experimental materials: Experimental group fertilizer: adopt the multifunctional fertilizer (according to the formula of embodiment 3: polyacrylamide 8 parts, humic acid 13 parts, organic fertilizer 45 parts, NPK fertilizer 20 parts, bentonite 8 parts) of the application.

[0066] Control group fertilizer: Blank control group (CK1): no fertilizer; Conventional fertilizer group (CK2): equal amount of ordinary NPK fertilizer (N-P2O5-K2O=15-15-15).

[0067] Experimental crop: corn (typical crop sensitive to water and nutrients).

[0068] Experimental soil: sandy loam soil in semi-arid area (poor water retention capacity, easy to verify water retention effect), initial pH 6.2, organic matter content 1.2%, field water holding capacity 25%.

[0069] Experimental steps: 1. Soil preparation: select sandy loam soil areas with similar fertility, divide into 12 plots (3 groups x 4 repetitions), each plot area is 30m² (6m x 5m).

[0070] 2. Plot planning: randomly arrange the groups, and set 4 repetitions for each group (avoid marginal effect).

[0071] 3. Fertilizer treatment: apply base fertilizer before sowing, the experimental group uses 40kg / acre, CK2 applies equal N-P-K nutrient amount (about 30kg / acre), and CK1 does not apply fertilizer.

[0072] 4. Irrigation control: normal irrigation during seedling stage to jointing stage (maintain field water holding capacity 70%); stop irrigation after jointing stage, simulate drought stress (target field water holding capacity decreases to 40%-50%).

[0073] 5. Regular detection: · Water retention index: measure 0-20cm soil moisture content every 7 days (3 times per plot) by TDR; · Drought resistance index: measure leaf relative water content (RWC) and malondialdehyde (MDA) content after jointing stage; measure corn yield (converted to yield per mu) at harvest; · Fertilization index: detect soil organic matter (permanganate method), available phosphorus (Olsen method) and available potassium (flame photometry) before sowing and after harvesting.

[0074] 6. Data analysis: use SPSS for variance analysis (p<0.05), and compare the differences between the experimental group and the control group.

[0075] Experimental results: Effects of the farmland drought-resistant water-retaining and fertilizer-boosting multifunctional fertilizer on soil and crops: Time point / indicator Experimental group (multi-functional fertilizer) Conventional fertilizer group (CK2) Blank control group (CK1) Soil moisture content (0-20 cm, %) Jointing stage (early drought) 22.1±1.2 18.5±0.8 15.3±0.6 Grain filling stage (mid-drought) 18.3±0.9 14.2±0.7 11.1±0.5 Harvesting stage 16.5±0.7 12.8±0.6 9.2±0.4 Soil organic matter content (%) Before sowing 1.2 1.2 1.2 After harvesting 2.8±0.2 1.8±0.1 1.1±0.1 Maize yield (kg / acre) 685±25 520±20 380±15 Analyzing the above experimental results found: 1. Water retention effect: The soil moisture content of the experimental group was significantly higher than that of CK2 and CK1 during the drought stress period (jointing to grain filling period), and remained 16.5% at the harvest period (CK2 was only 12.8%, and CK1 was only 9.2%), indicating that the fertilizer can effectively extend the soil water supply time in semi-arid areas.

[0076] 2. Drought resistance effect: The corn yield of the experimental group reached 685 kg / acre, which was 31.7% and 80.3% higher than that of CK2 (520 kg / acre) and CK1 (380 kg / acre), respectively, verifying its role in alleviating drought stress.

[0077] 3. Fertilization effect: The soil organic matter content of the experimental group after harvest reached 2.8% (increased by 133% compared with before sowing), which was significantly higher than that of CK2 (1.8%) and CK1 (1.1%); at the same time, the effective phosphorus and available potassium contents were increased by 25% and 18% respectively compared with CK2, indicating that the fertilizer can significantly improve the soil fertility in semi-arid areas and promote nutrient utilization.

[0078] Experiment two I. Experimental purpose To verify the unique effects of the layered wrapping process (core layer + intermediate layer + wrapping layer) of the present application in improving the structural stability of the fertilizer, controlling the release rate of nutrients, enhancing water retention performance, and retaining the activity of functional components, and to compare the differences with non-layered wrapping process.

[0079] II. Experimental materials and grouping · Experimental group (T): using complete layered wrapping process (steps two to six): Core layer: organic fertilizer particles (step two); Intermediate layer: NPK fertilizer coating (step three); Wrapping layer: polyacrylamide + humic acid + bentonite mixed coating (steps five to six).

[0080] · Control group: CK1: without intermediate layer (only core layer + wrapping layer): omit step three, directly mix organic fertilizer particles with wrapping layer; CK2: without wrapping layer (only core layer + intermediate layer): omit steps five to six, only use NPK to coat organic fertilizer particles; CK3: No layering (raw materials are directly mixed and granulated): all raw materials (organic fertilizer, NPK, polyacrylamide, humic acid, bentonite) are directly mixed and granulated without layering structure.

[0081] • Base formula: the raw material ratio of Example 3 (8 parts of polyacrylamide, 13 parts of humic acid, 45 parts of organic fertilizer, 20 parts of NPK fertilizer, and 8 parts of bentonite) is used.

[0082] III. Experimental steps 1. Raw material pretreatment: all raw materials (organic fertilizer fermentation, NPK crushing, polyacrylamide NaCl treatment, humic acid activation, and bentonite sodiumization) are treated according to Step One of Example 5.

[0083] 2. Granulation and coating with different processes: T group: complete layering and coating of core layer → intermediate layer → coating layer according to Steps Two to Six; CK1: Step Two → Steps Five to Six (no intermediate layer, directly coat the core layer with the coating layer); CK2: Step Two → Step Three (no coating layer, only coat the core layer with the intermediate layer); CK3: all raw materials are directly mixed and fed into the double-screw granulator for granulation (without layering).

[0084] 3. Key indicator detection: Structural stability: determine the compression strength of the granules and the breakage rate (the proportion of granules ≥4mm and ≤2mm after sieving); Nutrient release characteristics: determine the available nutrients (1h water extraction N, P, K) and long-acting nutrients (the time for continuous leaching until the nutrient concentration is <5%); Water retention performance: determine the water absorption ratio (the weight ratio of water absorption after 24h immersion of dry granules) and water evaporation rate (the surface water evaporation rate of granules in a simulated drought environment); Functional ingredient retention: • Polyacrylamide hydrogel formation ability (microscopic observation of the thickness of the surface gel layer after the granules are exposed to water); • Humic acid active group retention rate (titration method to determine carboxyl content); • Swelling capacity of bentonite (swelling volume of bentonite after sodiumization).

[0085] IV. Key detection indicators and methods Indicator category Detection index Detection method Structural stability Particle compression strength (N / particle) Particle strength tester (take 2-4 mm particles to measure single particle crushing pressure) Damage rate (%) Vibrating screen method (after simulating transportation vibration for 30 minutes, the proportion of ≥4 mm and ≤2 mm particles) Nutrient release characteristics Available nutrient release rate (%) Water leaching method (particle immersion in deionized water for 1 h, the proportion of N, P, and K content in the total nutrient content in the filtrate) Long-acting nutrient release period (days) Simulated soil leaching experiment (time to reach < 5% of initial concentration of nutrient in leachate) Water retention performance Water absorption ratio (g / g) Weighing method (dry particles were immersed in deionized water for 24 h, and the weight ratio before and after water absorption was calculated) Water evaporation rate (% / h) Place the particles in a constant temperature and humidity box (25℃, humidity 40%), and weigh every hour to calculate the water loss proportion Functional ingredient retention Hydrogel layer thickness (μm) Microscope method (after the particle swells in water, observe the surface gel layer thickness by slicing) Humic acid active group (mmol / g) Acid-base titration method (determine the total amount of carboxyl and phenolic hydroxyl groups) Bentonite swelling capacity (mL / g) National standard method (GB / T 20973-2007, sodium-based bentonite swelling capacity determination) V. Experimental results and analysis Performance comparison between layering and coating process and non-layering process: Indicator / group Experimental group (T) CK1 (no intermediate layer) CK2 (no wrapping layer) CK3 (no layering) Particle compression strength (N / particle) 14.2±1.3 9.8±0.9 11.5±1.1 7.2±0.7 Damage rate (%) 8±2 25±3 18±2 35±4 Available nutrient release rate (%) 32±2 48±3 65±4 75±5 Long-acting nutrient release period (days) 95±5 70±4 50±3 35±3 Water absorption ratio (g / g) 160±8 120±6 90±5 75±4 Water evaporation rate (% / h) 1.2±0.1 2.5±0.2 3.8±0.3 4.5±0.4 Hydrogel layer thickness (μm) 120±10 80±8 0 (no wrapping layer) 50±5 Humic acid active group (mmol / g) 2.7±0.2 2.0±0.1 1.8±0.1 1.5±0.1 Bentonite swelling capacity (mL / g) 8.3±0.3 7.5±0.2 4.0±0.2 3.8±0.2 Analysis conclusion: 1. Structural stability: The layered coating process (T group) supports the toughness of the core layer (organic fertilizer), tightly fills the intermediate layer (NPK), and reinforces the surface of the wrapping layer (high molecular material), with a particle compression strength of 14.2 N / particle (CK3 only 7.2 N / particle) and a breakage rate of only 8% (CK3 up to 35%), significantly improving the anti-crushing ability during transportation and application.

[0086] 2. Nutrient release regulation: The layered structure realizes "quick-acting + long-acting" coordinated fertilizer supply: The intermediate layer (NPK) provides quick-acting nutrients (T group 1h release rate 32%), avoiding the risk of nutrient sudden release of CK2 (no wrapping layer, release rate 65%); The wrapping layer (polyacrylamide + humic acid + bentonite) forms a slow-release barrier, with a long-term period of up to 95 days (CK3 only 35 days), meeting the needs of the whole growth period of crops.

[0087] 3. Enhanced water retention performance: The polyacrylamide of the wrapping layer absorbs water to form a 120 μm hydrogel layer, and the sodium bentonite expands to a volume of 8.3 mL / g, making the water absorption rate of the T group reach 160 g / g (CK3 only 75 g / g), and the water evaporation rate only 1.2% / h (CK3 up to 4.5% / h), effectively alleviating drought stress.

[0088] 4. Functional component retention: The layered process avoids the high temperature / mechanical damage caused by direct mixing of raw materials (CK3): The retention rate of active groups of humic acid is increased by 80% compared with CK3 (2.7 vs 1.5 mmol / g); The sodiumization effect of bentonite is not disturbed (swelling volume 8.3 mL / g vs 3.8 mL / g of CK3).

[0089] In summary, the layered coating process of the present application significantly improves the structural stability, nutrient regulation ability and drought resistance and water retention performance of the fertilizer through the synergistic effect of the core layer (organic fertilizer retention) → intermediate layer (NPK quick-acting) → wrapping layer (water retention and slow release), verifying the unique advantages of its process design.

[0090] Obviously, the above embodiments are only examples for clear illustration, and not a limitation on the implementation. For ordinary skilled persons in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the implementation. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A multifunctional fertilizer for drought resistance, water retention, and fertilization in farmland, characterized in that, It comprises the following components by weight parts: starch grafting acrylic acid SAP 2-6 parts, cyclopentanone 1-4 parts, enzymatic brown algae extract 2-6 parts, straw charcoal 1-4 parts, polyglutamic acid 1-4 parts, betaine 1-4 parts, polyacrylamide 2-6 parts, humic acid 6-12 parts, organic fertilizer 40-50 parts, NPK fertilizer 15-25 parts and bentonite 5-10 parts, wherein the organic fertilizer is fermented by 70% chicken manure, 20% pig manure and 10% straw powder.

2. The drought-resisting, water-retaining, and fertility-improving multifunctional fertilizer for farmland according to claim 1, characterized in that, It comprises the following components by weight parts: starch grafting acrylic acid SAP 2 parts, cyclopentanone 1 part, enzymatic brown algae extract 2 parts, straw charcoal 1 part, polyglutamic acid 1 part, betaine 1 part, polyacrylamide 2 parts, humic acid 6 parts, organic fertilizer 40 parts, NPK fertilizer 15 parts and bentonite 5 parts.

3. The multi-functional fertilizer for drought resisting, water preserving and nutrient enriching in farmland according to claim 1, characterized in that, It comprises the following components by weight parts: starch grafting acrylic acid SAP 4 parts, cyclopentanone 3 parts, enzymatic brown algae extract 3 parts, straw charcoal 2 parts, polyglutamic acid 2 parts, betaine 2 parts, polyacrylamide 4 parts, humic acid 8 parts, organic fertilizer 45 parts, NPK fertilizer 20 parts and bentonite 8 parts.

4. The multi-functional fertilizer for drought resisting, water preserving and nutrient accumulating in farmland according to claim 1, characterized in that, It comprises the following components by weight parts: starch grafting acrylic acid SAP 6 parts, cyclopentanone 4 parts, enzymatic brown algae extract 6 parts, straw charcoal 4 parts, polyglutamic acid 4 parts, betaine 4 parts, polyacrylamide 6 parts, humic acid 12 parts, organic fertilizer 50 parts, NPK fertilizer 25 parts and bentonite 10 parts.

5. A preparation method of a farmland drought-resistant water-retaining and fertility-improving multifunctional fertilizer, the preparation steps of the farmland drought-resistant water-retaining and fertility-improving multifunctional fertilizer prepared according to any weight parts of claims 1-4 are as follows, characterized in that: Step one, raw material pretreatment: first, the organic fertilizer is fermented for 30 days, and the pile is turned over 3 times during the process, then the compost is dried to a moisture content of less than 30%, and the compost is mixed with straw charcoal according to the proportion, finally the mixed straw charcoal and compost are crushed to pass through a 20-mesh screen; The NPK fertilizer and cyclopentanone are premixed according to the proportion, then crushed to pass through a 40-mesh screen, and the particle diameter is ≤0.42mm; The polyacrylamide and starch grafting acrylic acid are crushed to 80 mesh, and the particle diameter is ≤0.18mm, then treated by spraying with 20% NaCl solution, wherein the water:NaCl=4:1; The humic acid is mixed with KOH at a ratio of 10:1 for activation, dried and crushed to 60-80 mesh after aging for 24 hours; The bentonite is modified by sodiumization, 4% Na2CO3 is added to the bentonite, then dried to a water content of ≤8%, and finally crushed to pass through a 60-mesh screen; Step two, core layer granulation: the treated organic fertilizer is put into a double-screw extrusion granulator for granulation treatment to form organic fertilizer particles as the core layer of the fertilizer; Step three, middle layer coating: the organic fertilizer particles are put into the pretreated NPK fertilizer particles for middle layer coating to form the basic fertilizer; Step four, the preparation of the adhesive solution: prepare a 15% concentration of fulvic acid solution 60 parts, powder seaweed extract 5 parts, betaine 2 parts, polyvinyl alcohol 3 parts and water 30 parts, 60℃ water bath dissolving polyvinyl alcohol, cooling to 40℃ after adding fulvic acid solution, powder seaweed extract, enzymatic brown algae extract, polyglutamic acid, betaine and water, filtration to form the adhesive solution for standby; Step five, the mixing of the wrapping layer: mix the pretreated polyacrylamide, starch grafted acrylic acid, humic acid and bentonite uniformly to form the wrapping layer; Step six, the coating of the wrapping layer: evenly wrap the adhesive solution on the surface of the base fertilizer, and then put it into the wrapping layer for coating to form the fertilizer semi-product; Step seven, low temperature drying: put the fertilizer semi-product into the drying machine for low temperature drying; Step eight, vacuum impregnation: vacuumize the low temperature dried fertilizer semi-product to-0.08MPa for 20 minutes, then soak it in the impregnation solution under normal pressure for 30 minutes, drain and then dry for the second time; Step nine, microbial coating: use fluidized bed bottom spraying technology to coat the vacuum impregnated fertilizer semi-product, control the inlet air temperature to be 35℃, and after coating, use 2% CaCl2 solution for spraying crosslinking and solidification; Step ten, screening and packaging: screen the microbial coating treated fertilizer semi-product, and then package to obtain the fertilizer product multifunctional fertilizer.

6. The method for preparing the multi-functional fertilizer for drought resistance, water conservation and fertilizer enrichment in farmland according to claim 5, characterized in that, In step six, the adhesive solution is sprayed, the spraying pressure is 0.8MPa, the atomization particle size is 50-80μm, and the adhesive solution addition amount is 8-10% of the total weight of the base fertilizer.

7. The method for preparing the multi-functional fertilizer for drought resisting, water preserving and fertilizer enriching in farmland according to claim 5, characterized in that, In step seven, the low temperature drying uses counterflow rotary dryer, the inlet air temperature is ≤80℃, and the drying is carried out until the moisture content of the particles is ≤8%.

8. The method for preparing the multi-functional fertilizer for drought resisting, water preserving, and nutrient accumulating in farmland according to claim 5, characterized in that, In step eight, the impregnation solution is composed of 3% abscisic acid, 2% potassium silicate and 30% ethanol solution.

9. The method for preparing the multi-functional fertilizer for drought resisting, water preserving, and nutrient accumulating in farmland according to claim 5, characterized in that, In step ten, the vibration screen is used to separate the qualified particles of 2-4mm, the oversize material ≥4mm is returned to the granulator for regrinding, and the undersize material ≤2mm is returned to the middle layer coating process.

10. The method for preparing the multi-functional fertilizer for drought resistance, water conservation and fertilizer enrichment in farmland according to claim 5, characterized in that, In step nine, the coating liquid used for coating is mixed by 3% sodium alginate solution 70 parts, 50 billion CFU / g bacillus subtilis suspension 20 parts and 2% chitosan acetic acid solution 10 parts.

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