A kind of seedling culture medium nutrient soil and its production method using organic solid waste

Abstract

A method for preparing a seedling substrate nutrient soil is provided. The method uses corn stalks and cow dung as raw materials, sequentially prepares a humus substrate through a pretreatment step, an infiltration step, and a catalysis step, then performs a slaking treatment on the humus substrate, mixes the slaking humus substrate with sandy soil, perlite, pumice, vermiculite, coconut shell, polyglutamic acid, and chitosan, and adds purified water to obtain a water content of 40 to 50%. The seedling substrate nutrient soil prepared by the present invention is coordinated by four mechanisms: chemical water absorption, physical water storage, gradient water release, and stable structure. After absorbing water, the substrate can store enough water and slow down water loss through the pore structure, so that water and nutrients in the nutrient soil are maintained for a long time without loss. After watering for 2 weeks, the substrate water content is still stable at 40 to 50%, which is conducive to the rapid growth and reproduction of the seedling root system during the seedling cultivation process.

Description

Technical Field

[0001] The invention relates to the technical field of seedling cultivation substrate preparation, and in particular to a nutrient seedling cultivation substrate soil and a production method thereof using organic solid waste. Background Art

[0002] Nutrient soil is specially formulated to support the growth and development of seedlings during the seedling raising process. It contains a variety of mineral nutrients, is loose and aerated, retains water and fertilizer, and is pest and disease-free. Nutrient soil for seedlings is typically composed of fertile field soil, organic ingredients like coconut coir and humus, inorganic ingredients like perlite and vermiculite, and functional additives like slow-release fertilizers and water-retaining agents.

[0003] The water retention and nutrient stability of the seedling medium are crucial for seedling growth. Poor water retention leads to rapid drying of the medium and water deprivation of the roots; excessive water retention can lead to water accumulation, oxygen deprivation, and root rot. Therefore, an ideal medium strikes a balance between water retention and air permeability. Because seedling roots are underdeveloped and have weak absorption capacity, they require a constant supply of water to avoid drought stress. Nutrients must be dissolved in water to be absorbed by the roots, and a medium with good water retention stabilizes nutrient concentration and reduces loss. A medium with good and stable water retention provides continuous moisture during seed germination, preventing the seed coat in the medium from drying out or back-drying out, and promoting uniform seedling emergence. A moderately moist environment stimulates root expansion, and a stable water supply reduces stress responses in seedlings, allowing for good leaf expansion, enhanced photosynthesis, and improved stress resistance.

[0004] If the moisture content of the substrate remains stable for a short period of time, the substrate will dry out quickly, causing the seedlings to wilt and stagnate. In severe cases, the roots will age and even die. Frequent watering to replenish moisture will cause nutrients to be lost with the water, making the substrate infertile. Frequent watering can also cause the pores in the substrate to be frequently filled with water in a short period of time, leading to water accumulation. The roots, lacking oxygen, cannot carry out aerobic respiration, their energy supply is interrupted, and the root tip cells begin to die, manifesting as browning and rotting of the roots (commonly known as "root rot"), and the loss of their absorption function.

[0005] Therefore, it is necessary to further explore a seedling medium that can retain water for a long time and keep the water content stable within the range suitable for seedling cultivation. Summary of the Invention

[0006] The present invention aims to provide a seedling culture medium nutrient soil based on organic solid waste.

[0007] The present invention aims to provide a method for preparing a seedling-growing substrate. This method produces a high-quality humus substrate, which is then compounded with other organic and inorganic components. The resulting substrate exhibits long-lasting, stable water retention and nutrient distribution, maintaining a moisture content of 40-50% over a long period of time, thereby improving the quality of the substrate for seedling cultivation.

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

[0009] A high-quality humus, characterized in that: corn straw and cow dung are used as raw materials, and the humus is prepared through a pretreatment step, an infiltration step and a catalysis step in sequence, and then further subjected to a aging treatment. In the catalysis step, a carboxyl maltose iron aqueous solution and titanium dioxide are added to the mixed raw material powder after the infiltration treatment, and after uniform mixing, the mixture is placed in a closed environment at 180-200° C. and a pressure of 1.5-1.8 MPa to react for 2-4 hours.

[0010] Furthermore, in the catalytic treatment, the mass ratio of the carboxyl maltose iron aqueous solution, the mixed raw material powder and titanium dioxide is 2~3:100:0.5~1, and the mass percentage concentration of the carboxyl maltose iron aqueous solution is 0.1%~0.2%.

[0011] Furthermore, the pretreatment step is to take 20-30 parts of dry corn stalks and 10-15 parts of dry cow dung by weight, mix them, place them in a grinder and grind them until the diameter of the corn stalks is 3-5 mm to obtain mixed raw material powder.

[0012] Furthermore, the infiltration step is to spray a 0.5% by mass citric acid solution into the pretreated mixed raw material powder, and then let it stand for 24 to 36 hours after mixing. The mass ratio of the mixed raw material powder to the citric acid solution is 100:15 to 20.

[0013] Furthermore, the aging treatment is to add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 28-32° C. in a closed environment and mature for 5-7 days.

[0014] Furthermore, in the aging treatment, the components are calculated by weight as follows: 55-65 parts of humus base material, 2-3 parts of seaweed extract, 0.2-0.3 parts of live nitrogen-fixing bacteria, 0.7-1.1 parts of potassium dihydrogen phosphate, and 1.5-1.8 parts of dipotassium hydrogen phosphate.

[0015] A method for preparing high-quality humus using organic solid waste is characterized in that: corn straw and cow dung are used as raw materials, and humus is prepared through a pretreatment step, an infiltration step and a catalysis step in sequence, and then further aging treatment is performed. In the catalysis step, a carboxyl maltose iron aqueous solution and titanium dioxide are added to the mixed raw material powder after the infiltration treatment, and after uniform mixing, the mixture is placed in a closed environment at 180-200°C and a pressure of 1.5-1.8 MPa to react for 2-4 hours.

[0016] Furthermore, in the catalytic treatment, the mass ratio of the carboxyl maltose iron aqueous solution, the mixed raw material powder and titanium dioxide is 2~3:100:0.5~1, and the mass percentage concentration of the carboxyl maltose iron aqueous solution is 0.1%~0.2%.

[0017] Humus can absorb water and nutrients through its colloidal structure, but inferior humus has low colloidal activity and insufficient porosity, which leads to weakened soil water retention capacity (water is easily lost) or excessive stickiness (water retention). At the same time, nutrients are easily leached with water, increasing the risk of pollution.

[0018] In the present invention, when preparing the humus substrate, carboxymaltose iron and titanium dioxide are used to jointly catalyze the hydrolysis of straw and cow dung to prepare a high-quality humus substrate, which plays an important role in maintaining the stability of the moisture content, matrix structure and nutrient distribution of the matrix. The organic ligand (carboxymaltose) of carboxymaltose iron in the present invention can be adsorbed on the surface of TiO2, thereby increasing the Fe 3+ Dispersion, avoid agglomeration, and stabilize iron ions through chelation, retaining more active sites and promoting charge separation; in addition, TiO2 can adsorb reduced Fe 2+ , which is then oxidized to Fe 3+ , avoid Fe 2+ Due to excessive accumulation, precipitation occurs (such as the formation of Fe (OH)2), thereby stabilizing the redox balance of the catalytic system and assisting catalytic redox, thereby preparing high-quality humus substrate.

[0019] Furthermore, the pretreatment step is to take 20-30 parts of dry corn stalks and 10-15 parts of dry cow dung by weight, mix them, place them in a grinder and grind them until the diameter of the corn stalks is 3-5 mm to obtain mixed raw material powder.

[0020] Furthermore, the infiltration step is to spray a 0.5% by mass citric acid solution into the pretreated mixed raw material powder, and then let it stand for 24 to 36 hours after mixing. The mass ratio of the mixed raw material powder to the citric acid solution is 100:15 to 20.

[0021] Furthermore, the aging treatment is to add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 28-32° C. in a closed environment and mature for 5-7 days.

[0022] Furthermore, in the aging treatment, the components are calculated by weight as follows: 55-65 parts of humus base material, 2-3 parts of seaweed extract, 0.2-0.3 parts of live nitrogen-fixing bacteria, 0.7-1.1 parts of potassium dihydrogen phosphate, and 1.5-1.8 parts of dipotassium hydrogen phosphate.

[0023] Most specifically, a method for preparing high-quality humus from organic solid waste is characterized by comprising the following steps:

[0024] (1) Pretreatment: 20-30 parts by weight of dry corn stalks and 10-15 parts of dry cow dung are mixed and crushed in a grinder until the diameter of the corn stalks is 3-5 mm to obtain a mixed raw material powder;

[0025] (2) Infiltration: Spray a 0.5% by mass fraction of citric acid solution into the pretreated mixed raw material powder, let it stand for 24 to 36 hours after mixing, and the mass ratio of the mixed raw material powder to the citric acid solution is 100:15 to 20;

[0026] (3) Catalysis: adding carboxymaltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment, mixing evenly, placing it in a closed environment at 180-200 ° C and a pressure of 1.5-1.8 MPa for reaction for 2-4 hours, the mass ratio of carboxymaltose iron aqueous solution, mixed raw material powder and titanium dioxide is 2-3:100:0.5-1, and the mass percentage concentration of the carboxymaltose iron aqueous solution is 0.1%-0.2%;

[0027] (4) Ripening: Add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate to the humus substrate. In a closed environment, set the temperature to 28-32°C and ripen for 5-7 days. The components are calculated by weight as follows: 55-65 parts of humus substrate, 2-3 parts of seaweed extract, 0.2-0.3 parts of live nitrogen-fixing bacteria, 0.7-1.1 parts of potassium dihydrogen phosphate, and 1.5-1.8 parts of dipotassium hydrogen phosphate.

[0028] A seedling substrate nutrient soil is characterized by: using corn stalks and cow dung as raw materials, sequentially performing a pretreatment step, an infiltration step, and a catalysis step to prepare a humus substrate, then subjecting the humus substrate to a maturation treatment, and then mixing the maturated humus substrate with sandy soil, perlite, pumice, vermiculite, coconut shell, polyglutamic acid, and chitosan, and adding purified water to obtain a water content of 40-50%.

[0029] Furthermore, the pretreatment step in preparing the humus substrate is to take 20-30 parts of dry corn stalks and 10-15 parts of dry cow dung by weight, mix them, place them in a grinder and grind them until the diameter of the corn stalks is 3-5 mm to obtain mixed raw material powder.

[0030] Furthermore, the infiltration step is to spray a 0.5% by mass citric acid solution into the pretreated mixed raw material powder, and then let it stand for 24 to 36 hours after mixing. The mass ratio of the mixed raw material powder to the citric acid solution is 100:15 to 20.

[0031] Furthermore, the catalytic step is to add carboxyl maltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment, mix them evenly, and place them in a closed environment at 180~200℃ and a pressure of 1.5~1.8Mpa to react for 2~4h.

[0032] Furthermore, in the catalytic step, the mass ratio of the carboxyl maltose iron aqueous solution, the mixed raw material powder and titanium dioxide is 2~3:100:0.5~1, and the mass percentage concentration of the carboxyl maltose iron aqueous solution is 0.1%~0.2%.

[0033] Furthermore, the aging treatment is to add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 28-32° C. in a closed environment and mature for 5-7 days.

[0034] Furthermore, in the aging treatment, the components are calculated by weight as follows: 55-65 parts of humus base material, 2-3 parts of seaweed extract, 0.2-0.3 parts of live nitrogen-fixing bacteria, 0.7-1.1 parts of potassium dihydrogen phosphate, and 1.5-1.8 parts of dipotassium hydrogen phosphate.

[0035] Furthermore, in terms of weight, the seedling matrix nutrient soil comprises 55 to 65 parts of mature humus base material, 100 to 120 parts of sandy soil, 12 to 15 parts of perlite, 3 to 5 parts of pumice, 5 to 8 parts of vermiculite, 8 to 10 parts of coconut shell, 4 to 6 parts of polyglutamic acid, and 2 to 3 parts of chitosan.

[0036] A method for preparing nutrient soil for a seedling culture medium is characterized by: using corn stalks and cow dung as raw materials, sequentially performing a pretreatment step, an infiltration step, and a catalysis step to prepare a humus substrate, then subjecting the humus substrate to a maturation treatment, and then mixing the maturated humus substrate with sandy soil, perlite, pumice, vermiculite, coconut shell, polyglutamic acid, and chitosan, and adding purified water to obtain a water content of 40-50%.

[0037] Furthermore, the pretreatment step in preparing the humus substrate is to take 20-30 parts of dry corn stalks and 10-15 parts of dry cow dung by weight, mix them, place them in a grinder and grind them until the diameter of the corn stalks is 3-5 mm to obtain mixed raw material powder.

[0038] Furthermore, the infiltration step is to spray a 0.5% by mass citric acid solution into the pretreated mixed raw material powder, and then let it stand for 24 to 36 hours after mixing. The mass ratio of the mixed raw material powder to the citric acid solution is 100:15 to 20.

[0039] Furthermore, the catalytic step is to add carboxyl maltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment, mix them evenly, and place them in a closed environment at 180~200℃ and a pressure of 1.5~1.8Mpa to react for 2~4h.

[0040] Furthermore, in the catalytic step, the mass ratio of the carboxyl maltose iron aqueous solution, the mixed raw material powder and titanium dioxide is 2~3:100:0.5~1, and the mass percentage concentration of the carboxyl maltose iron aqueous solution is 0.1%~0.2%.

[0041] Furthermore, the aging treatment is to add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 28-32° C. in a closed environment and mature for 5-7 days.

[0042] Furthermore, in the aging treatment, the components are calculated by weight as follows: 55-65 parts of humus base material, 2-3 parts of seaweed extract, 0.2-0.3 parts of live nitrogen-fixing bacteria, 0.7-1.1 parts of potassium dihydrogen phosphate, and 1.5-1.8 parts of dipotassium hydrogen phosphate.

[0043] Furthermore, in terms of weight, the seedling matrix nutrient soil comprises 55 to 65 parts of mature humus base material, 100 to 120 parts of sandy soil, 12 to 15 parts of perlite, 3 to 5 parts of pumice, 5 to 8 parts of vermiculite, 8 to 10 parts of coconut shell, 4 to 6 parts of polyglutamic acid, and 2 to 3 parts of chitosan.

[0044] Most specifically, a method for preparing a seedling-growing substrate nutrient soil is characterized by comprising the following steps:

[0045] 1. Preparation of humus substrate

[0046] (1) Pretreatment: 20-30 parts by weight of dry corn stalks and 10-15 parts of dry cow dung are mixed and crushed in a grinder until the diameter of the corn stalks is 3-5 mm to obtain a mixed raw material powder;

[0047] (2) Infiltration: Spray a 0.5% by mass fraction of citric acid solution into the pretreated mixed raw material powder, let it stand for 24 to 36 hours after mixing, and the mass ratio of the mixed raw material powder to the citric acid solution is 100:15 to 20;

[0048] (3) Catalysis: adding carboxymaltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment, mixing evenly, placing it in a closed environment at 180-200 ° C and a pressure of 1.5-1.8 MPa for reaction for 2-4 hours, the mass ratio of carboxymaltose iron aqueous solution, mixed raw material powder and titanium dioxide is 2-3:100:0.5-1, and the mass percentage concentration of the carboxymaltose iron aqueous solution is 0.1%-0.2%;

[0049] 2. Mature humus substrate

[0050] Add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 28-32°C in a closed environment and mature for 5-7 days. The components are calculated by weight as follows: 55-65 parts of humus substrate, 2-3 parts of seaweed extract, 0.2-0.3 parts of viable nitrogen-fixing bacteria, 0.7-1.1 parts of potassium dihydrogen phosphate, and 1.5-1.8 parts of dipotassium hydrogen phosphate;

[0051] 3. Compound nutrient soil

[0052] According to weight, 55-65 parts of mature humus substrate, 100-120 parts of sandy soil, 12-15 parts of perlite, 3-5 parts of pumice, 5-8 parts of vermiculite, 8-10 parts of coconut shell, 4-6 parts of polyglutamic acid, and 2-3 parts of chitosan are mixed evenly, and purified water is added to the water content of 40-50% to obtain seedling matrix nutrient soil.

[0053] Nutrient soil, with its core being sandy soil, has poor water retention. To improve the water retention capacity of the substrate, existing technologies typically add large amounts of synthetic polymeric water-retaining agents. These agents form highly viscous gels after absorbing water. If the amount used exceeds the pore capacity of the substrate, the substrate particles can become cemented, pores can become clogged, and eventually compaction can occur. While using natural water-retaining agents can avoid the problem of clumping, they struggle to maintain a stable substrate moisture content over the long term and can lead to new problems. For example, relying on large amounts of chitosan, polyglutamic acid, and other agents for water retention can lead to excess water retention, resulting in a heavy and sticky substrate and hindered root growth. Furthermore, the substrate's air permeability decreases, causing respiratory and metabolic disorders in the roots, leading to distortions. Furthermore, the microbial ecosystem within the substrate becomes unbalanced. Rapid water loss also reduces the efficiency of nutrient dissolution and migration, leading to nutrient deficiencies and damaging the substrate's physical structure. Subsequent watering makes it difficult for water to penetrate, resulting in "surface runoff," further exacerbating water loss.

[0054] In the composite nutrient soil matrix, perlite, pumice, and coconut shell form a coarse-pore framework for drainage and ventilation, while the vermiculite and humus base provide fine pores for deep water storage. Small amounts of polyglutamic acid and chitosan form a network to lock in moisture, creating a gradient water-release system. The colloidal adsorption of humus and the high-molecular-weight water-locking properties of polyglutamic acid create a dual chemical water-retention mechanism. Chitosan optimizes water distribution through structural modification. Together, these three elements "fix" water within the matrix pores, creating efficient water storage and, through a gradient water-release mechanism, ensure long-term water stability within the matrix.

[0055] The slow biodegradation of humus and coconut shells, combined with the inert support of perlite and pumice, ensures the long-term stability of the matrix structure and prevents the degradation of water retention over time. The biological components (humus and coconut shells) and the inert minerals (perlite and pumice) form a "dynamic-static" support system. Microbial activity maintains structural activity, while the inert materials prevent structural collapse, ensuring long-term stability of the matrix porosity and preventing water loss due to structural damage. Ultimately, this creates a closed-loop, four-step synergistic network of chemical water absorption, physical water storage, gradient water release, and structural stability, maintaining a stable water retention rate of 40%-50% for 15 days.

[0056] The present invention has the following technical effects:

[0057] The seedling raising matrix nutrient soil prepared by the present invention cooperates through four mechanisms of chemical water absorption, physical water storage, gradient water release and stable structure, so that after the matrix absorbs water, it can not only store sufficient water, but also slow down water loss through the pore structure, so that the water and nutrients in the nutrient soil are maintained for a long time without loss. After watering for 2 weeks, the water content of the matrix is ​​still stable at 40-50%, which is conducive to the rapid growth and reproduction of the seedling root system during the seedling raising process. DETAILED DESCRIPTION

[0058] The present invention is described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention.

[0059] Example 1

[0060] A method for preparing a seedling-raising substrate nutrient soil comprises the following steps:

[0061] 1. Preparation of humus substrate

[0062] (1) Pretreatment: 30 parts by weight of dry corn stalks and 10 parts by weight of dry cow dung were mixed, and the mixture was crushed in a grinder until the diameter of the corn stalks was 3-5 mm to obtain a mixed raw material powder;

[0063] (2) Infiltration: Spray 0.5% by mass of citric acid solution into the pretreated mixed raw material powder, let it stand for 36 hours after mixing, and the mass ratio of the mixed raw material powder to the citric acid solution is 100:15;

[0064] (3) Catalysis: Add carboxymaltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment, mix them evenly, and place them in a closed environment at 200°C and a pressure of 1.5 MPa for reaction for 4 hours. The mass ratio of carboxymaltose iron aqueous solution, mixed raw material powder and titanium dioxide is 3:100:0.5, and the mass percentage concentration of the carboxymaltose iron aqueous solution is 0.1%;

[0065] 2. Mature humus substrate

[0066] Add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 28°C in a closed environment and mature for 7 days. The components are calculated by weight as follows: 55 parts of humus substrate, 2 parts of seaweed extract, 0.2 parts of viable nitrogen-fixing bacteria, 0.7 parts of potassium dihydrogen phosphate, and 1.5 parts of dipotassium hydrogen phosphate;

[0067] 3. Compound nutrient soil

[0068] According to weight parts, 55 parts of mature humus substrate, 100 parts of sandy soil, 12 parts of perlite with a particle size of 1-3 mm, 3 parts of pumice with a particle size of 1-3 mm, 5 parts of vermiculite with a particle size of 0.5-1.0 mm, 8 parts of coconut shells, 4 parts of polyglutamic acid, and 2 parts of chitosan are mixed evenly, and purified water is added to the water content to reach 50% to obtain seedling matrix nutrient soil.

[0069] Example 2

[0070] A method for preparing a seedling-raising substrate nutrient soil comprises the following steps:

[0071] 1. Preparation of humus substrate

[0072] (1) Pretreatment: 20 parts by weight of dry corn stalks and 15 parts by weight of dry cow dung were mixed, and the mixture was crushed in a grinder until the diameter of the corn stalks was 3-5 mm to obtain a mixed raw material powder;

[0073] (2) Infiltration: Spray a 0.5% by mass fraction of citric acid solution into the pretreated mixed raw material powder, let it stand for 24 hours after mixing, and the mass ratio of the mixed raw material powder to the citric acid solution is 100:20;

[0074] (3) Catalysis: adding carboxymaltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment, mixing evenly, placing it in a closed environment at 180°C and a pressure of 1.8 MPa for reaction for 2 hours, the mass ratio of carboxymaltose iron aqueous solution, mixed raw material powder and titanium dioxide is 2:100:1, and the mass percentage concentration of the carboxymaltose iron aqueous solution is 0.2%;

[0075] 2. Mature humus substrate

[0076] Add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 32°C in a closed environment and mature for 5 days. The components are calculated by weight as follows: 65 parts of humus substrate, 3 parts of seaweed extract, 0.3 parts of viable nitrogen-fixing bacteria, 1.1 parts of potassium dihydrogen phosphate, and 1.8 parts of dipotassium hydrogen phosphate;

[0077] 3. Compound nutrient soil

[0078] According to weight parts, 65 parts of mature humus substrate, 120 parts of sandy soil, 15 parts of perlite with a particle size of 1-3 mm, 5 parts of pumice with a particle size of 1-3 mm, 8 parts of vermiculite with a particle size of 0.5-1.0 mm, 10 parts of coconut shells, 6 parts of polyglutamic acid, and 3 parts of chitosan are mixed evenly, and purified water is added to the water content to reach 40% to obtain seedling matrix nutrient soil.

[0079] Example 3

[0080] A method for preparing a seedling-raising substrate nutrient soil comprises the following steps:

[0081] 1. Preparation of humus substrate

[0082] (1) Pretreatment: 25 parts by weight of dry corn stalks and 12 parts by weight of dry cow dung were mixed, and the mixture was crushed in a grinder until the diameter of the corn stalks was 3-5 mm to obtain a mixed raw material powder;

[0083] (2) Infiltration: Spray 0.5% by mass of citric acid solution into the pretreated mixed raw material powder, let it stand for 30 hours after mixing, and the mass ratio of the mixed raw material powder to the citric acid solution is 100:18;

[0084] (3) Catalysis: adding carboxymaltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment, mixing evenly, placing it in a closed environment at 190°C and a pressure of 1.6 MPa for reaction for 3 hours, the mass ratio of carboxymaltose iron aqueous solution, mixed raw material powder and titanium dioxide is 2.5:100:0.8, and the mass percentage concentration of the carboxymaltose iron aqueous solution is 0.15%;

[0085] 2. Mature humus substrate

[0086] Add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 30°C in a closed environment and mature for 6 days. The components are calculated by weight as follows: 60 parts of humus substrate, 2.5 parts of seaweed extract, 0.25 parts of viable nitrogen-fixing bacteria, 1.0 parts of potassium dihydrogen phosphate, and 1.6 parts of dipotassium hydrogen phosphate;

[0087] 3. Compound nutrient soil

[0088] According to weight parts, 60 parts of mature humus substrate, 110 parts of sandy soil, 14 parts of perlite with a particle size of 1-3 mm, 4 parts of pumice with a particle size of 1-3 mm, 6 parts of vermiculite with a particle size of 0.5-1.0 mm, 9 parts of coconut shells, 5 parts of polyglutamic acid, and 2.5 parts of chitosan are mixed evenly, and purified water is added to the water content to reach 45% to obtain seedling matrix nutrient soil.

[0089] Comparative Example 1

[0090] Compared with Example 3, the difference is that in the step of preparing the humus substrate, only a single TiO2 is used for catalysis, and the remaining steps are the same as Example 3.

[0091] Comparative Example 2

[0092] Compared with Example 3, the difference is that in the step of preparing the humus substrate, only a single carboxymaltose iron aqueous solution is used for catalysis, and the remaining steps are the same as Example 3.

[0093] Comparative Example 3

[0094] Compared with Comparative Example 2, the difference is that in the step of preparing the humus substrate, a single 0.1% ferric chloride solution is used to replace the carboxymaltose ferric aqueous solution during catalysis, and the remaining steps are the same as Comparative Example 2.

[0095] Comparative Example 4

[0096] Compared with Example 3, the difference is that in the step of preparing the humus substrate, a 0.1% by mass ferric chloride solution is used to replace the carboxymaltose ferric aqueous solution during catalysis, and the remaining steps are the same as in Example 3.

[0097] Humic acid content is an important indicator of the quality of humic substances. Furthermore, the humic acid / fulvic acid (H / F) ratio, functional group density, and molecular weight distribution are also important indicators for evaluating the quality of humic substances. The humic acid content, H / F ratio (potentiometric titration, measuring the proportion of carboxyl and phenolic hydroxyl groups in the humic substances) of the humic substrates prepared in Example 3, Comparative Examples 1, and 2 were analyzed. Table 1 shows the results of the blank control group, which was mostly obtained by treating the humic substrates without any catalyst and then maturing them under the same temperature and pressure conditions.

[0098] Table 1:

[0099]

[0100] High humic acid content and high functional group density mean that humus is highly active, with stronger ion exchange, complexing ability and fertilizer retention. In addition, the higher the humus H / F ratio, the more stable the humus structure and the stronger the fertilizer retention ability. As can be seen from the above, the humic acid content, H / F and functional group density in the humus substrate prepared by each embodiment of the present invention are all at a relatively high level, while in Comparative Example 1, a single TiO2 is used as a catalyst to catalyze the oxidation of raw materials. The humic acid content, H / F and functional group density in the prepared humus are similar to those in the blank control group, indicating that a single TiO2 does not play a good catalytic effect in the preparation process. After the catalysis of a single carboxyl maltose iron, the quality of the humus is significantly improved. However, in Example 3, after the composite catalysis of TiO2 and carboxyl maltose iron, TiO2 and carboxyl maltose iron produce a synergistic catalytic effect, which significantly improves the quality of the final humus. In Comparative Example 3, a single ferric chloride solution was used to replace the carboxylic maltose iron in Comparative Example 2 to catalyze the preparation of a humus substrate. The quality of the humus obtained was significantly higher than that of Comparative Example 2. However, after being used in combination with TiO2, the quality of the humus obtained was not as good as that of Example 3 in which TiO2 and carboxylic maltose iron were combined. It can be seen that the synergistic effect between the two is poor.

[0101] The physical and chemical properties of the final substrate nutrient soil prepared in each embodiment and each comparative example were tested.

[0102] Testing of physical and chemical performance indicators of seedling matrix nutrient soil:

[0103] (1) Soil bulk density test

[0104] Soil bulk density refers to the dry weight of soil per unit volume (including pores) in its natural state, expressed in g / cm³. It is calculated by sampling with a knife ring method, drying, and weighing:

[0105] 1. Sampling: Press the ring knife vertically into the soil, keeping the soil structure intact, flatten the ends and seal them.

[0106] 2. Wet weight: Weigh the total weight of the ring cutter + wet soil (M), and record the ring cutter's own weight (G).

[0107] 3. Measure the moisture content of the soil: Take some wet soil and use the drying method to determine the moisture content (W%).

[0108] 4. Soil dry weight = (M - G) × (1-W%)

[0109] 5. Ring volume V = π × (radius²) × height.

[0110] 6. Bulk density = soil dry weight / ring knife volume

[0111] (2) Ventilation Pore Detection

[0112] Air pores (non-capillary pores) refer to the large pores in the soil through which air can flow freely. The water loss after water absorption is calculated as follows:

[0113] 1. Sampling: Collect undisturbed soil samples using a circular cutter.

[0114] 2. Saturated water absorption: Soak the ring knife in water for 12 hours and weigh it to obtain the maximum water holding capacity (M3).

[0115] 3. Remove non-capillary water: Place the ring knife on dry sand for 2 hours and weigh it to obtain the capillary water holding capacity (M4).

[0116] Calculate according to the following formula:

[0117] Non-capillary porosity = 0.1 × (M3 - M4) × matrix density / 1.0 (water density)

[0118] (3) Water-holding pore detection

[0119] Water-holding pores (capillary pores) refer to the micropores in the soil that retain water through capillary action. The calculation formula is:

[0120] Capillary porosity = (0.1 × M4 × matrix density) / 1.0 8 .

[0121] (IV) Organic matter testing

[0122] Ignition method (loss on ignition method) Weigh the dried soil sample ( W1 ), burned in a muffle furnace at 550℃ for 4 hours, and weighed after cooling ( W2 ), calculated according to the following formula:

[0123] Organic matter content = ( W1 - W2 ) / W1 × 100%

[0124] (V) Humic acid detection

[0125] Potassium dichromate oxidation method: Potassium dichromate is used to oxidize the organic carbon in humic acid under acidic conditions, and the humic acid content is calculated by titrating the remaining oxidant:

[0126] Sample preparation: Grind and sieve the air-dried soil sample (0.149 mm) and weigh 0.2-0.5 g.

[0127] Oxidation reaction: Add 0.8 mol / L potassium dichromate solution and concentrated sulfuric acid, heat at 170-180°C for 5 minutes to fully oxidize the humic acid;

[0128] Titration: Using o-phenanthroline as the indicator, titrate with ferrous sulfate standard solution to the endpoint (orange-red → brick-red), and record the consumption. Calculate according to: Humic acid content (%) = [(blank titration volume - sample titration volume) × ferrous sulfate concentration × 0.003 × 1.724 × 100] / sample dry weight.

[0129] (6) Cation exchange capacity

[0130] Soil treatment: Take an air-dried soil sample and pass it through a 0.25 mm sieve. Weigh 1-5 g (depending on the soil type) and place it in a centrifuge tube.

[0131] Ion exchange: Add 1 mol / L ammonium acetate solution (pH 7.0 or 8.5, depending on the soil pH) and shake for 30 minutes to fully replace cations.

[0132] Washing and extraction: Wash with 95% ethanol to remove free NH 4+ , after centrifugation, the supernatant was collected;

[0133] Distillation titration: Add magnesium oxide to distill and release NH3, absorb it with boric acid solution and titrate with standard hydrochloric acid solution to calculate CEC.

[0134] The test results of the performance indicators of the matrix nutrient soil in each group are shown in Table 2.

[0135] Table 2:

[0136]

[0137] From the above data, it can be seen that due to the large difference in humus prepared in each comparative example, the bulk density of the matrix nutrient soil formed by the compounding is significantly higher than that of each embodiment, and the total pore size is significantly reduced (invalid porosity is ignored), the air permeability and water holding capacity of the matrix nutrient soil are reduced, and the cation exchange capacity is also significantly reduced, which is not conducive to the growth during the seedling cultivation process. Among them, the matrix nutrient soil corresponding to humus (Comparative Example 2 and Comparative Example 3) prepared by the separate carboxyl maltose iron and ferric chloride groups can be compared. It can be seen that the overall effect of the ferric chloride group is slightly better than that of the carboxyl maltose iron group, but in the matrix nutrient soil (Example 3 and Comparative Example 4) corresponding to humus prepared by composite use with TiO2, TiO2 and carboxyl maltose iron produce a significant synergistic effect after composite, which improves the quality of the humus prepared, and plays a positive regulatory role in the various physical and chemical indicators of the subsequent matrix nutrient soil. In Comparative Example 4, most of the physical and chemical indicators are significantly worse than those of the single ferric chloride group of Comparative Example 3, which shows that TiO2 and ferric chloride produce a synergistic effect that is not conducive to the quality of humus during the preparation of humus.

[0138] In addition, after watering the nutrient soil of each group, the TDR moisture sensor was used to record the moisture content 24 hours after watering as the first day of the test. The moisture content on the 1st, 3rd, 7th, and 15th days was tested in sequence. The results are shown in Table 3.

[0139] Table 3:

[0140]

[0141] From matrix nutrition soil after watering the 1st day, each group matrix nutrition soil water content is all between 70~75%, and it can be seen from the 3rd day detection water content change that the water content of the matrix nutrition soil of each embodiment drops to within 50%, and then extends as the detection number of days, and the water content of each embodiment changes extremely slowly, and after 15 days, water content still maintains more than 40%.And the matrix nutrition soil corresponding to each comparative example is all higher than 50% at the 3rd day test water content, and then extends as the detection number of days, and the water content in matrix nutrition soil significantly decreases, and the water content in 15 days matrix nutrition soil has dropped to less than 30%.Illustrate that the humus prepared by each comparative example significantly affects the water holding capacity of matrix nutrition soil in matrix nutrition soil.

[0142] In the process of compounding the matrix nutrient soil, in addition to the significant impact of humus quality on the physical and chemical properties of the matrix nutrient soil, the formulation of the remaining components also significantly affects the air permeability and water retention of the matrix nutrient soil. Based on Example 3, we experimented with removing polyglutamic acid (Group 1) and chitosan (Group 2) from the composite formula, as well as removing both polyglutamic acid and chitosan (Group 3). The physical and chemical indicators of the matrix nutrient soil compounded in each group are shown in Table 4.

[0143] Table 4:

[0144]

[0145] As can be seen from the table, in group 1 without polyglutamic acid, the cation exchange capacity of the matrix nutrient soil decreased, while the cation exchange capacity increased in group 2 without chitosan. After watering, the macromolecular water retention without polyglutamic acid in group 1 relied solely on humus for water retention, and the water content in the matrix nutrient soil decreased rapidly, and the water retention performance decreased significantly. Although group 2 had dual water retention due to humus colloid adsorption and polyglutamic acid macromolecular water locking, there was no chitosan to regulate the water distribution path, and the water content in the matrix nutrient soil also decreased rapidly. Group 3 did not have polyglutamic acid and chitosan, and the rate of decrease of the water content of the matrix nutrient soil was reduced instead, indicating that in the embodiment of the present invention, after humus and polyglutamic acid efficiently retained water, chitosan was still needed to optimize the water distribution in order to "fix" the water in the matrix pores and achieve long-term stability of the water in the matrix through the gradient water release mechanism. Without the dual water retention of humus and polyglutamic acid, the introduction of chitosan into the matrix nutrient soil to regulate the water distribution path will accelerate the loss of water in the matrix nutrient soil.

Claims

1. A method for preparing a seedling culture medium nutrient soil, characterized in that: Corn straw and cow dung are used as raw materials, and a humus substrate is prepared through a pretreatment step, an infiltration step and a catalysis step in sequence. The humus substrate is then matured, and the matured humus substrate is mixed with sandy soil, perlite, pumice, vermiculite, coconut shell, polyglutamic acid and chitosan, and purified water is added to the mixture until the water content is 40-50%. The infiltration step is to spray a citric acid solution with a mass fraction of 0.5% into the pretreated mixed raw material powder, and the mixture is allowed to stand for 24-36 hours after mixing. The mixed raw material powder and the citric acid solution are mixed. The mass of the citric acid solution is 100:15~20, and the catalytic step is to add a carboxyl maltose iron aqueous solution and titanium dioxide to the mixed raw material powder after the infiltration treatment. After mixing, it is placed in a closed environment at 180~200 ° C and a pressure of 1.5~1.8 MPa for 2~4 hours. The mass ratio of the carboxyl maltose iron aqueous solution, the mixed raw material powder and titanium dioxide in the catalytic step is 2~3:100:0.5~1, and the mass percentage concentration of the carboxyl maltose iron aqueous solution is 0.1%~0.2%.

2. The method for preparing a seedling culture medium nutrient soil according to claim 1, wherein: The pretreatment step in preparing the humus substrate is to take 20-30 parts of dry corn stalks and 10-15 parts of dry cow dung by weight, mix them, place them in a grinder and grind them until the diameter of the corn stalks is 3-5 mm to obtain mixed raw material powder.

3. The method for preparing a seedling culture medium nutrient soil according to claim 2, wherein: The aging treatment is to add seaweed extract, nitrogen-fixing bacteria, potassium dihydrogen phosphate and dipotassium hydrogen phosphate to the humus substrate, set the temperature at 28-32° C. in a closed environment and mature for 5-7 days.

4. The method for preparing a seedling culture medium nutrient soil according to claim 3, wherein: In the aging treatment, the components are calculated by weight as follows: 55-65 parts of humus base material, 2-3 parts of seaweed extract, 0.2-0.3 parts of live nitrogen-fixing bacteria, 0.7-1.1 parts of potassium dihydrogen phosphate, and 1.5-1.8 parts of dipotassium hydrogen phosphate.

5. The method for preparing a seedling culture medium nutrient soil according to claim 4, wherein: Calculated by weight, the seedling matrix nutrient soil comprises 55 to 65 parts of mature humus base material, 100 to 120 parts of sandy soil, 12 to 15 parts of perlite, 3 to 5 parts of pumice, 5 to 8 parts of vermiculite, 8 to 10 parts of coconut shell, 4 to 6 parts of polyglutamic acid, and 2 to 3 parts of chitosan.

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