A seedling substrate based on rice straw and biogas residue, its preparation method and application

Abstract

This invention provides a seedling substrate based on rice straw and biogas residue and its preparation method. The substrate consists of basic raw materials and additives. The basic raw materials, by weight, include 50% decomposed rice straw, 20% biogas residue, and 30% vermiculite. The additives are 1% ferrous sulfate, 1% superphosphate, 1% ammonium sulfate, and 0.5% amino acid fertilizer, added according to the total weight of the basic raw materials. The seedling substrate of this invention has an alkaline available nitrogen content of 1204 mg / kg, an available phosphorus content of 730 mg / kg, an available potassium content of 2841 mg / kg, a pH of 7.19, an electrical conductivity of 3.23 mS / cm, a total porosity of 82%, and a bulk density of 0.30 g / cm³. 3 It can be applied to rice seedling transplanting, producing high-quality seedlings with strong seedling establishment ability and low seedling cost. It can not only promote the resource utilization of rice straw and biogas residue and reduce environmental pollution, but also has good economic, ecological and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization technology of straw, specifically relating to a seedling substrate based on rice straw and biogas residue, its preparation method and application. Background Technology

[0002] Caofeidian District, located in the central Bohai Rim region and belonging to the coastal saline-alkali area of ​​eastern Hebei (Tangshan and Qinhuangdao), is a major rice-producing area in Hebei Province, with a rice planting area of ​​approximately 320,000 mu (about 21,333 hectares). It requires about 9.6 million trays of 9-inch machine-transplanted rice seedlings annually, generating approximately 250,000 tons of straw after harvest. Investigations revealed that some farmers use a mixture of natural soil and seedling-strengthening agents to create their own seedling-raising nutrient soil, while seedling cooperatives purchase seedling substrate from other regions. Homemade nutrient soil makes it difficult to cultivate high-quality machine-transplanted seedlings on a large scale, directly resulting in inconsistent seedling quality. Furthermore, natural soil resources are limited, and long-term uncontrolled excavation will damage the ecosystem. While purchasing seedling substrate from other regions can cultivate high-quality seedlings, the high transportation costs and difficulties increase seedling production costs and may delay agricultural progress. Therefore, developing a localized, low-cost, and environmentally friendly rice machine-transplanting seedling substrate is an urgent task for the district.

[0003] Rice straw is rich in nutrients such as nitrogen, phosphorus, and potassium, making it an important organic resource. Biogas residue is a biological fermentation product produced from the anaerobic fermentation of organic matter such as livestock and poultry manure, containing large amounts of humic acid, organic matter, and nutrients such as nitrogen, phosphorus, and potassium. Both composted straw and biogas residue are agricultural solid wastes, rich in nutrients. However, straw raw materials have a complex structure, primarily composed of cellulose, hemicellulose, and lignin, which form a compact crystalline structure, affecting their biodegradability. This results in low degradation rates, slow fermentation initiation, and long fermentation times. Furthermore, due to the low temperatures in the rice-growing areas of eastern Hebei during autumn and winter, specific low-temperature-resistant microorganisms are needed to rapidly initiate composting under low-temperature conditions. If local rice straw and biogas residue are properly disposed of and developed into a substrate for mechanized rice transplanting, it can not only solve the problems of large soil consumption, difficulty in obtaining soil, and serious damage to the topsoil in self-made nutrient soil, but also increase the high-value utilization of straw, solve the problem of idle agricultural waste from factories around Caofeidian, save on rice seedling production costs, realize the recycling of waste in rice production, and have good economic, ecological and social benefits, which is conducive to the sustainable development of agriculture. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a rice seedling substrate based on rice straw and biogas residue, its preparation method and application. This invention, through screening the mixing ratio of basic raw materials for rice seedling substrate, screening acidifiers, screening nutrient fertilizers, and field verification experiments, finally arrives at a formula for developing a rice machine-transplanting seedling substrate using agricultural waste such as decomposed rice straw and biogas residue.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A seedling substrate based on rice straw and biogas residue, the seedling substrate being composed of basic raw materials and additives, wherein the basic raw materials include, by weight ratio, 30-80% decomposed rice straw, 10-30% biogas residue and 10-50% vermiculite, and the additives are, by weight ratio, 1-5% ferrous sulfate, 0.5-5% superphosphate, 0-5% ammonium bicarbonate, 0-5% monoammonium phosphate, 0.5-5% ammonium sulfate and 0.5-2% amino acid fertilizer.

[0007] Preferably, the seedling substrate is composed of basic raw materials and additives. The basic raw materials include 50% decomposed rice straw, 20% biogas residue and 30% vermiculite by weight. The additives are 1% ferrous sulfate, 1% superphosphate, 1% ammonium sulfate and 0.5% amino acid fertilizer added according to the total weight of the basic raw materials.

[0008] Preferably, the composted rice straw is prepared by soaking autumn-harvested rice straw in a 1% calcium hydroxide solution for 36-60 hours, then transferring it to a 1% ferrous sulfate solution for 12-36 hours. After the combined pretreatment with calcium hydroxide and ferrous sulfate, 1% of self-developed HT20 composting agent and 1% urea are added according to the dry weight of the rice straw for composting. It can be fully composted after 30-50 days.

[0009] The self-developed HT20 composting agent is composed of the following raw materials in parts by weight: 20-50 parts of termite fungus Isoptericola sp., 2-50 parts of Trichoderma longibrachiatum, 20-50 parts of Streptomyces finlayi, 20-50 parts of Staphylococcus sp., 10-30 parts of Bacillus subtilis, and 10-30 parts of Bacillus mucilaginosus.

[0010] Preferably, the biogas residue comes from agricultural waste produced by a biomass energy company.

[0011] The present invention also provides a method for preparing the seedling substrate based on rice straw and biogas residue, wherein the method comprises: weighing the basic raw materials and additives according to the formula ratio and mixing them evenly.

[0012] The present invention also provides an application of the seedling substrate based on rice straw and biogas residue, wherein the seedling substrate is used for machine transplanting of rice seedlings.

[0013] This invention, by adopting the above technical solutions, has significant technical effects:

[0014] 1. This invention provides a localized, low-cost, and environmentally friendly rice seedling substrate, which not only solves the problem of inconsistent quality of machine-transplanted rice seedlings in the Jidong rice-growing area, but also develops diversified utilization technology for rice straw. At the same time, it finds a reasonable way to utilize biogas residue as agricultural waste. It can not only promote the resource utilization process of rice straw and biogas residue, reduce environmental pollution, and protect the ecological environment, but also has good economic, ecological and social benefits, which is conducive to the green and sustainable development of agriculture.

[0015] 2. This invention utilizes autumn-harvested rice straw and adds a self-developed HT20 composting agent that can be activated at low temperatures to accelerate the composting process. This promotes the rapid composting of rice straw in autumn and winter, and it can be used as a raw material for rice seedling substrate in the following spring. This not only realizes the green recycling of rice straw, but also provides a new technical method for the diversified utilization of rice straw.

[0016] 3. The seedling substrate of this invention contains 1204 mg / kg of available nitrogen, 730 mg / kg of available phosphorus, 2841 mg / kg of available potassium, has a pH of 7.19, an electrical conductivity of 3.23 mS / cm, a total porosity of 82%, and a bulk density of 0.30 g / cm³. 3 Compared to farmers preparing their own nutrient soil, this invention uses a mixture of decomposed rice straw and biogas residue with vermiculite as the base material, reducing the bulk density of the rice seedling substrate for machine transplanting, thus alleviating the burden of transportation in actual production. Furthermore, the addition of ferrous sulfate and amino acid fertilizer as acidifiers for the seedling substrate not only adjusts the pH of the substrate but also increases the chlorophyll content of the leaves, thereby improving the quality of the seedlings.

[0017] 4. This invention utilizes a rice seedling substrate prepared from a mixture of decomposed rice straw, biogas residue, and vermiculite, with a seedling cost of approximately 0.7 yuan per tray. Commercially available seedling substrates cost approximately 2 yuan per tray, but carry the risk of long-distance transportation. Farmers' homemade nutrient soil costs approximately 0.3 yuan per tray. However, natural soil resources are finite and cannot be exploited indefinitely. Furthermore, homemade nutrient soil has a high bulk density, increasing labor costs and wear on rice transplanters. This invention provides a green, pollution-free, and low-cost rice seedling substrate that can replace farmers' homemade substrates made from natural soil and commercially available substrates. It ensures seedling quality, reduces seedling costs, minimizes mechanical wear, and increases the economic value of rice.

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a dynamic diagram of tillering of different varieties of rice seedlings cultivated using different seedling substrates under field conditions in Embodiment 3 of the present invention;

[0020] Figure 2 This is a dynamic growth diagram of the plant height of different varieties of rice seedlings cultivated using different seedling substrates under field conditions, as shown in Example 3 of this invention. Detailed Implementation

[0021] Example 1

[0022] This embodiment describes the screening of basic raw materials for rice seedling transplanting substrate.

[0023] Composting rice straw: Utilizing autumn-harvested rice straw, it is soaked in a 1% calcium hydroxide solution for 48 hours, then transferred to a 1% ferrous sulfate solution for 24 hours. After this combined calcium hydroxide-ferrous sulfate pretreatment, 1% of a self-developed HT20 composting agent and 1% urea are added based on the dry weight of the rice straw. Straw processing begins in mid-November, and composting takes 50 days to achieve complete composting. The self-developed HT20 composting agent consists of the following raw materials in parts by weight: 20 parts of *Isoptericola* sp., 20 parts of *Trichoderma longibrachiatum*, 20 parts of *Streptomyces finlayi*, 50 parts of *Staphylococcus* sp., 30 parts of *Bacillus subtilis*, and 30 parts of *Bacillus mucilaginosus*.

[0024] The biogas residue comes from agricultural waste produced by biomass energy companies in eastern Hebei Province and has high nutritional value.

[0025] 1. Basic physicochemical properties of raw materials

[0026] Table 1 shows the basic physicochemical properties of decomposed rice straw, biogas residue, and commercial seedling substrate (Jiangsu Chaimihe Co., Ltd.). The table reveals that the pH of decomposed rice straw and biogas residue is significantly higher than the acidic standard for rice seedling substrates. The electrical conductivity of both decomposed rice straw and biogas residue is higher than that of the commercial substrate, and their potassium and sodium ion contents are significantly higher. The organic matter content is as high as 700g / kg-1100g / kg, and they possess abundant readily available potassium nutrients. However, the alkaline-available nitrogen content is slightly lower than that of the commercial substrate. Therefore, in the later stages of raw material formulation, attention should be paid to adjusting the pH of the substrate formula, the impact of ions on seedling quality, and addressing issues such as insufficient nitrogen content.

[0027] Table 1. Basic physicochemical properties of commercially available matrices and raw materials of this invention.

[0028]

[0029] 2. Screening of Rice Seedling Transplanting Substrate Formula

[0030] Commercial seedling substrate was used as the control group (CK-base), and the rest were treatment groups. The specific raw material composition for each treatment is shown in Table 2. Each treatment group consisted of 10 volumes (each volume being 1000 cm³). 3 Add 50g of commercial soil acidifier to the substrate.

[0031] Table 2 Specific raw material ratios for different treatments

[0032]

[0033]

[0034] The seedlings under different treatments were investigated, and the results are shown in Table 3. Except for the CK-based treatment, the seedlings in the other treatments were yellowish-green, with narrow and short leaves. Some treatments showed uneven seedling emergence and varying heights. From the overall quality of the seedlings in treatments A1, A2, and A3, it was found that a higher proportion of decomposed rice straw did not necessarily promote seedling growth. Using 50% decomposed rice straw in the formula was sufficient to meet the normal growth needs of the seedlings while mitigating the inhibitory effects of certain elements in the decomposed rice straw. Therefore, 50% decomposed rice straw was ultimately selected, along with other raw materials to ensure normal seedling growth.

[0035] Biogas residue is rich in nutrients, and vermiculite can maintain the permeability and water retention of the substrate. Therefore, a mixture of biogas residue and vermiculite with well-rotted rice straw was used to prepare the seedling substrate. Based on the seedling quality of treatments B4 and B5, treatment B5 seedlings had four leaves, and their stem base width and leaf width were slightly greater than those of treatment B4. Furthermore, the overall color of the seedlings in treatment B5 was slightly greener than those in other treatments. Therefore, the final seedling substrate formulation was based on the B5 formula.

[0036] Table 3. Results of the survey on seedling quality under different treatments

[0037]

[0038] The above experiments determined that the basic raw material ratio of the rice seedling raising substrate for machine transplanting is 50% decomposed rice straw + 20% biogas residue + 30% vermiculite.

[0039] Example 2

[0040] This embodiment describes the screening of acidifiers and nutrient fertilizers for rice machine transplanting substrate.

[0041] 1. Indoor test

[0042] Add 5g of seedling substrate base material (50% decomposed rice straw + 20% biogas residue + 30% vermiculite) to a 100mL Erlenmeyer flask. At the same time, add ferrous sulfate, superphosphate, ammonium bicarbonate, monoammonium phosphate and ammonium sulfate to the Erlenmeyer flask according to different concentrations. Add 50mL of distilled water, shake and filter, and measure pH and conductivity. The results are shown in Table 4. Table 4 shows that as the concentration of ferrous sulfate increases, the pH value decreases, and the matrix gradually becomes acidic, but the conductivity increases. With increasing superphosphate concentration, the increase in pH and conductivity is relatively small, showing a stable overall trend. The matrix with added ammonium bicarbonate is alkaline, possibly because after ammonium bicarbonate dissolves in water, the main free ions are bicarbonate and ammonium ions. The hydrolysis degree of bicarbonate ions is greater than that of ammonium ions, resulting in a higher concentration of hydroxide ions, ultimately leading to an alkaline solution. With increasing monoammonium phosphate concentration, the pH decreases slightly, by about 6, but the conductivity increases significantly. When the concentration of monoammonium phosphate is 5%, the pH is approximately 5.92, and the conductivity is 4.36 mS / cm. With increasing ammonium sulfate concentration, the pH change is small, around 7, and ammonium sulfate is a typical acidic fertilizer that can provide nitrogen fertilizer for plants.

[0043] Table 4. Effects of adding different acidic fertilizers on the pH and conductivity of the seedling substrate.

[0044]

[0045]

[0046] The effects of different acid-adjusting fertilizers on the pH and conductivity of rice seedling substrate were measured after compounding. The results are shown in Table 5. When the ferrous sulfate concentration is constant, increasing the concentration of superphosphate only slightly decreases the pH, but increases the conductivity. Therefore, a superphosphate concentration of 1% is sufficient in the compounding process. Increasing the concentrations of monoammonium phosphate and ammonium sulfate increases the conductivity. Therefore, when selecting different concentrations of acidic fertilizers, it is important to ensure that the pH is lowered without increasing the conductivity.

[0047] Table 5. Effects of adding compound acidic fertilizer on pH and electrical conductivity of seedling substrate.

[0048]

[0049]

[0050] 2. Greenhouse Experiment

[0051] Based on the results of indoor experiments measuring pH and conductivity, single and compound acidification treatments were selected to lower the substrate pH while having a slightly lower impact on conductivity. The effects of different acidification treatments on the basic physicochemical properties of the rice transplanting substrate were measured. Simultaneously, greenhouse seedling cultivation experiments were conducted to measure the quality of rice seedlings over a certain period, evaluating the impact of different acidifiers on rice seedlings and selecting a relatively suitable acidification treatment. The experimental scheme is shown in Table 6.

[0052] Table 6 Experimental schemes with different acidifiers

[0053]

[0054] The effects of adding different acidifiers on the basic physicochemical properties of rice seedling transplanting substrate are shown in Table 7. Table 7 shows that adding ferrous sulfate and superphosphate does not increase the content of available nitrogen in the substrate. Instead, adding monoammonium phosphate and ammonium sulfate increases the content of available nitrogen with increasing concentration. However, monoammonium phosphate significantly increases the content of available phosphorus in the substrate, and excessive phosphorus has a certain toxic effect on rice seedlings. Ammonium sulfate also significantly increases the content of available nitrogen with increasing concentration, but the increase in electrical conductivity is also large. Therefore, choosing a low concentration of ammonium sulfate can both increase the content of available nitrogen in the substrate and solve the problem of excessively high electrical conductivity. Although superphosphate does not increase the content of available nitrogen in the substrate, the addition of calcium ions promotes the improvement of rice seedling quality. Similarly, the iron ions in ferrous sulfate can promote chlorophyll synthesis in leaves.

[0055] Table 7. Effects of adding different acidifiers on the basic physicochemical properties of rice seedling transplanting substrate.

[0056]

[0057]

[0058] The effects of adding different acidifiers on rice seedlings are shown in Table 8. Treatments with ferrous sulfate and ammonium sulfate resulted in higher SPAD values ​​and greener leaves. The ammonium sulfate treatment also achieved a maximum leaf width of 4.2-4.6 cm, with wide and green leaves. In contrast, seedlings treated with only superphosphate were narrower and had yellowish leaves. Therefore, ferrous sulfate and ammonium sulfate can improve the quality of rice seedlings, resulting in dark green leaves, wide leaves, and thick stems.

[0059] Table 8 Effects of different acidification treatments on rice seedlings

[0060] deal with SPAD value Maximum leaf width / cm Stem diameter / cm CK base 32.28±2.61 4.54±0.07 2.48±0.15 A1 22.95±1.26 3.61±0.10 1.77±0.10 A2 20.99±1.74 3.52±0.06 1.89±0.01 A3 22.95±1.85 3.49±0.12 1.86±0.08 A4 22.43±1.75 3.52±0.11 1.83±0.12 B1 14.97±1.44 3.54±0.11 1.68±0.05 B2 19.99±2.85 3.51±0.09 1.67±0.19 B3 18.99±3.71 3.81±0.14 1.89±0.21 B4 15.79±2.37 3.41±0.08 1.74±0.08 B5 16.41±1.92 3.47±0.20 1.87±0.10 C1 18.85±0.97 3.98±0.08 2.06±0.06 C2 19.14±1.49 4.26±0.01 2.07±0.03 C3 17.99±0.76 4.22±0.09 2.00±0.03 C4 17.48±0.56 4.28±0.11 1.97±0.05 D1 22.39±1.84 4.24±0.13 2.15±0.11 D2 23.62±2.90 4.48±0.10 2.02±0.09 D3 26.12±1.09 4.64±0.34 2.12±0.26 D4 26.31±1.02 3.35±0.04 2.35±0.10

[0061] Amino acid fertilizers can stimulate and regulate rapid plant growth, promote nutrient absorption, enhance plant metabolism, improve photosynthesis, promote root development, and accelerate plant growth and reproduction. An amino acid fertilizer addition experiment was conducted, and the basic physicochemical properties of the rice transplanting substrate and the quality of the rice seedlings were measured to evaluate the effectiveness of the amino acid fertilizer. The formulation is shown in Table 9.

[0062] Table 9. Experimental formulations with different amino acid fertilizers added.

[0063]

[0064] The effects of adding different amino acid fertilizers on the physicochemical properties of rice seedling transplanting substrate are shown in Table 10. After adding amino acid fertilizer, the content of available nitrogen increased with increasing amino acid fertilizer concentration, but electrical conductivity and available potassium also increased, while the effect on pH and available phosphorus was minimal. When ammonium sulfate and amino acid fertilizer were added simultaneously, the electrical conductivity reached 2.6-3.95 mS / cm, with a slightly higher increase. However, when ammonium sulfate and amino acid fertilizer were added simultaneously, the content of available nitrogen both reached over 1000 mg / kg, which increased the nitrogen content in the substrate.

[0065] Table 10 Effects of adding different amino acid fertilizers on the physicochemical properties of rice seedling transplanting substrate.

[0066]

[0067]

[0068] The effects of adding different amino acid fertilizers on the quality of rice seedlings are shown in Table 11. When the amount of amino acid fertilizer added is above 1%, the SPAD value of rice seedlings increases, and the leaves are dark green. When the amount of amino acid fertilizer added is 2%, the quality of seedlings is not much different from that of seedlings treated with the CK substrate, but the electrical conductivity content reaches 3.52 mS / cm, which is too high and slightly affects the early emergence. When amino acid fertilizer and ammonium sulfate are added together, the SPAD value of rice seedlings increases significantly, and the maximum leaf width, stem diameter, and plant height are all higher than those of the single amino acid fertilizer addition. Among them, the quality of seedlings in the B4 treatment group is not much different from that of the commercial substrate, and the alkaline nitrogen content is the highest, reaching 1750 mg / kg, but the electrical conductivity reaches 3.95 mS / cm, which is slightly higher. The seedling effect of the B3 treatment group was second only to the B4 treatment group. At the same time, its electrical conductivity value was 2.88mS / cm, which had little impact on the early emergence. The seedlings emerged uniformly, with dark green leaves, thick stems and wide leaves, which met the standards for machine-transplanted rice seedlings.

[0069] Table 11 Effects of adding different amino acid fertilizers on rice seedlings

[0070]

[0071]

[0072] Superphosphate fertilizer can improve soil aggregate structure and soil environment. Therefore, experiments were conducted with different concentrations of superphosphate fertilizer. By measuring the physicochemical properties of the substrate and seedling quality indicators, the substrate formula for mechanized rice transplanting was further improved. The treatments with different concentrations of superphosphate fertilizer are shown in Table 12.

[0073] Table 12 Experimental formulations with different superphosphate fertilizers added

[0074]

[0075] The effects of adding different concentrations of superphosphate fertilizer on the physicochemical properties of rice transplanting substrate are shown in Table 13. Adding 1% superphosphate increases the content of available phosphorus compared to adding 0.5% superphosphate, but has no effect on available potassium. To a certain extent, adding superphosphate makes the substrate pH neutral, but because ammonium sulfate is absorbed along with ammonium ions, sulfate ions will make it acidic. The C3 treatment group has the highest content of available nitrogen and conductivity among all treatment groups, with a conductivity reaching 4.10 mS / cm. Due to its excessively high conductivity, it is not suitable as a substrate formulation.

[0076] Table 13 Effects of adding different superphosphate fertilizers on the physicochemical properties of rice seedling transplanting substrate.

[0077]

[0078]

[0079] The effects of different superphosphate fertilizer treatments on rice seedling quality are shown in Table 14. The C3 treatment group, with the highest available nitrogen content, had the highest SPAD value, dark green leaves, thick leaves, and thick stems. The seedling quality was similar to the CK substrate treatment, but due to its high substrate conductivity, early emergence was uneven. The C2 treatment group had a SPAD value of 28.94, green leaves, thick stems, dense and well-developed root systems, and uniform emergence. Therefore, the final formula for machine-transplanted seedlings was the C2 treatment group, namely 50% decomposed rice straw + 20% biogas residue + 30% vermiculite + 1% ferrous sulfate + 1% superphosphate + 1% ammonium sulfate.

[0080] +0.5% amino acid fertilizer.

[0081] Table 14 Effects of adding different superphosphate fertilizers on rice seedlings

[0082] deal with SPAD value Maximum leaf width / cm Stem diameter / cm Plant height / cm Number of seedlings CK-based 32.39±2.27 4.6±0.11 2.58±0.25 16.73±1.33 3.20±0.35 C1 27.75±0.92 4.33±0.21 2.32±0.08 16.67±0.31 3.13±0.23 C2 28.94±1.20 4.69±0.61 2.40±0.35 15.93±0.50 3 C3 32.77±1.11 4.91±0.12 2.67±0.06 16.00±1.11 3.20±0.20 C4 27.38±3.95 4.12±0.32 2.18±0.10 16.80±1.22 3.20±0.20 C5 28.61±4.36 4.72±0.19 2.57±0.32 15.73±0.50 3

[0083] Example 3

[0084] This embodiment is a field trial to verify the seedling substrate formula obtained after screening using Examples 1 and 2.

[0085] Four rice varieties with different grain types (7233, 979, Zhonghua 8, and Xiangnuo 9) were selected and rice seedlings were raised using the seedling substrate of this invention (50% decomposed rice straw + 20% biogas residue + 30% vermiculite + 1% ferrous sulfate + 1% superphosphate + 1% ammonium sulfate + 0.5% amino acid fertilizer) and a commercial seedling substrate (Jiangsu Chaimihe Co., Ltd.). After one month of cultivation, the seedlings were transplanted into the field. The differences between the seedling substrate of this invention (self-developed) and the commercial seedling substrate (CK-based) were comprehensively evaluated by regularly observing the number of tillers and plant height, as well as the impact on the components of rice yield.

[0086] Figure 1 and Figure 2The figures show the tillering and plant height of different rice varieties cultivated in different seedling substrates under field conditions. The solid line represents the changes in tillering and plant height of seedlings cultivated in the self-developed seedling substrate, while the dashed line represents the changes in tillering and plant height of seedlings cultivated in the commercial substrate. The figures show that the number of tillers and plant height of the four different rice varieties cultivated under the two different substrates did not differ significantly throughout the entire growth period. The highest number of tillers in the rice seedlings cultivated in the self-developed seedling substrate was greater than that in the rice seedlings cultivated in the commercial substrate, and the final effective number of tillers was also higher than that in the control group (CK substrate). During the seedling establishment period, the number of tillers did not differ significantly, indicating that the rice seedlings cultivated in the self-developed substrate had a certain establishment ability and were of higher quality. In terms of rice plant height, the two treatment groups were not significantly different. However, the plant height of the self-developed substrate treatment group of Zhonghua 8 was lower than that of the CK substrate control group in the early stage, which may have caused the difference in plant height during the seedling stage. By the final harvest, there was no significant difference in plant height between the two treatment groups. Through the investigation of rice seedling tiller number and plant height, it was found that there was no significant difference in field performance between seedlings cultivated with the self-developed seedling substrate and those cultivated with commercial seedling substrates, and no significant difference was found during the critical seedling establishment stage.

[0087] Table 15 shows the effects of different rice seedlings cultivated with different seedling substrates on the components of rice yield. There was almost no difference in the thousand-grain weight and seed setting rate between the two treatment groups. The number of panicles in the self-developed treatment group was slightly higher than that in the CK substrate control group; for varieties 7233 and Zhonghua 8, the number of grains per panicle in the self-developed treatment group was slightly higher than that in the CK substrate control group, and their final theoretical yield also increased accordingly. For varieties 979 and Xiangnuo 9, the number of grains per panicle in the self-developed treatment group was slightly lower than that in the CK substrate control group, but the difference was not significant. Although rice seedlings cultivated with the self-developed seedling substrate may affect the components of rice yield to some extent, there was no significant difference compared to the CK substrate control group. Therefore, the self-developed seedling substrate of this invention is suitable for machine-transplanted rice seedling cultivation. It produces high-quality seedlings with strong seedling establishment ability, and has no significant impact on the components of rice yield. It can completely replace the best-performing substrates on the market, reducing the cost of seedling substrates in the region, while simultaneously realizing the resource utilization of waste in the region, playing a crucial role in the development of circular agriculture.

[0088] Table 15. Effects of rice seedlings raised in different seedling substrates on the components of rice yield.

[0089]

[0090]

[0091] The seedling substrate of this invention contains 1204 mg / kg of available nitrogen, 730 mg / kg of available phosphorus, 2841 mg / kg of available potassium, has a pH of 7.19, an electrical conductivity of 3.23 mS / cm, a total porosity of 82%, and a bulk density of 0.30 g / cm³. 3 Compared to farmers preparing their own nutrient soil, this invention uses a mixture of decomposed rice straw and biogas residue with vermiculite as the base material, reducing the bulk density of the rice seedling substrate for machine transplanting. This reduces the burden of handling and mechanical wear in actual production. Furthermore, ferrous sulfate and amino acid fertilizers are used as acidifiers in the seedling substrate, which not only adjust the pH of the substrate but also increase the chlorophyll content of the leaves, thereby improving the quality of the seedlings.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A seedling substrate based on rice straw and biogas residue, characterized in that, The seedling substrate is composed of basic raw materials and additives. The basic raw materials include 30-80% decomposed rice straw, 10-30% biogas residue and 10-50% vermiculite by weight. The additives are 1-5% ferrous sulfate, 0.5-5% superphosphate, 0-5% ammonium bicarbonate, 0-5% monoammonium phosphate, 0.5-5% ammonium sulfate and 0.5-2% amino acid fertilizer added according to the total weight of the basic raw materials. The decomposed rice straw is prepared by soaking autumn-harvested rice straw in a 1% calcium hydroxide solution for 36-60 hours, then transferring it to a 1% ferrous sulfate solution for 12-36 hours. After this combined calcium hydroxide-ferrous sulfate pretreatment, 1% of a self-developed HT20 decomposition agent and 1% urea are added according to the dry weight of the rice straw for composting. It is fully decomposed after 30-50 days. The self-developed HT20 decomposition agent consists of the following raw materials in parts by weight: termite fungi. Isoptericola sp. 20-50 parts, Trichoderma longipes Trichoderma longibrachiatum 2-50 portions of Streptomyces finlei Streptomyces finlayi 20-50 servings of Staphylococcus aureus Staphylococcus sp. 20-50 portions of Bacillus subtilis Bacillus subtilis 10-30 parts and Bacillus colloidis Bacillus mucilaginosus 10-30 servings; The biogas residue comes from agricultural waste produced by a biomass energy company.

2. The seedling substrate based on rice straw and biogas residue according to claim 1, characterized in that, The seedling substrate is composed of basic raw materials and additives. The basic raw materials include 50% decomposed rice straw, 20% biogas residue and 30% vermiculite by weight. The additives are 1% ferrous sulfate, 1% superphosphate, 1% ammonium sulfate and 0.5% amino acid fertilizer added according to the total weight of the basic raw materials.

3. A method for preparing a seedling substrate based on rice straw and biogas residue as described in claim 1 or 2, characterized in that, The method is as follows: weigh the basic raw materials and additives according to the formula ratio, and then mix them evenly.

4. The application of a seedling substrate based on rice straw and biogas residue as described in claim 1 or 2, characterized in that, The seedling substrate is used for machine transplanting of rice seedlings.

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