A method for preparing and applying rice husk charcoal-modified substrate suitable for multi-mode rice seedling raising

Abstract

This invention provides a method for preparing and applying a rice husk charcoal-modified substrate suitable for multi-mode rice seedling raising, belonging to the field of rice seedling raising technology. The invention first soaks rice husk charcoal in water, then soaks it in a mixed solution of citric acid and ammonium sulfate, and finally air-dries the rice husk charcoal to obtain modified rice husk charcoal. Finally, the modified rice husk charcoal is mixed with different fertilizers to obtain a rice husk charcoal-modified substrate suitable for rice seedling raising in different modes. The rice husk charcoal-modified substrate prepared by this invention can be used not only in tray seedling raising but also has good seedling rolling effect in blanket tray seedling raising.

Description

Technical Field

[0001] This invention relates to the field of rice seedling cultivation technology, and in particular to a method for preparing and applying a rice husk char-modified substrate suitable for multi-mode rice seedling cultivation. Background Technology

[0002] Rice is one of my country's main food crops and plays a vital role in ensuring national food security. Mechanization of the entire rice planting process can improve production efficiency. Machine transplanting, including tray transplanting and pot transplanting, is a crucial step in this process. High-quality, standardized seedling raising directly affects the transplanting results, and a good seedling substrate directly determines the quality of the seedlings. Traditional seedling substrates are usually made by digging up field soil, crushing, sterilizing, and adjusting its pH. However, this method easily breeds weeds and causes soil-borne diseases, and long-term digging damages the soil's topsoil environment. With the continuous promotion of rice machine transplanting technology, the problem of difficulty in obtaining seedling substrate has become increasingly prominent. Therefore... People are constantly seeking alternative materials for preparing substrates. Currently, existing substrate materials include inorganic substrates such as vermiculite, perlite, slag, and rock wool, and organic substrates such as straw, sawdust, peat, coconut coir, earthworm castings, compost, and fermented Chinese medicinal herbs. In addition, there is biochar. In production, these organic substrates, inorganic substrates, biochar, and yellow mud, various fertilizers, and microbial agents are usually mixed in a certain proportion for rice seedling cultivation. However, the raw materials for some formulation processes are relatively complex, and coupled with the limited resources, this brings certain obstacles to agricultural production applications.

[0003] Biochar is produced by thermal pyrolysis of agricultural waste biomass under anaerobic conditions. Using biochar as a raw material to prepare rice seedling substrate can help alleviate the problem of soil acquisition in rice seedling cultivation, recycle agricultural waste biomass, and achieve the effect of carbon sequestration and emission reduction.

[0004] Depending on water management methods, seedling raising can be divided into wet seedling raising and dry seedling raising modes. To adapt to machine transplanting, two main types of seedling trays are currently used: blanket trays and pot trays. Blanket trays can only be used for machine transplanting, while pot trays can be used for both machine transplanting and machine seed throwing. Furthermore, blanket trays require good seedling rolling, while pot trays do not. Biochar is lightweight, has low bulk density, abundant pores, and a large specific surface area, exhibiting good adsorption and air permeability. However, it has weak water retention capacity, contains fewer nutrients, and is slightly alkaline. Therefore, considering the dual advantages and disadvantages of biochar, the different characteristics of different seedling raising modes, and the varying requirements of different seedling trays, it is necessary to develop biochar substrates and application methods suitable for both blanket trays and pot trays for different seedling raising modes. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing a rice husk char-modified substrate suitable for multi-mode rice seedling raising, comprising the following steps:

[0006] (1) Soak the rice husk charcoal in clean water for 1-2 days, then wash it with clean water 1-3 times;

[0007] (2) Soak the cleaned rice husk charcoal in a mixed solution of citric acid and ammonium sulfate for 1-2 days, repeat the soaking 2-3 times, and then air-dry the rice husk charcoal to obtain modified rice husk charcoal.

[0008] (3) Mix the modified rice husk char with and / or the substrate to obtain the rice husk char modified substrate suitable for multi-mode rice seedling raising.

[0009] Preferably, in the citric acid and ammonium sulfate mixed solution in step (2), the mass concentration of citric acid is 0.1% and the mass concentration of ammonium sulfate is 0.1%.

[0010] Preferably, the fertilizer in step (3) is at least one of organic fertilizer and inorganic fertilizer; the substrate is at least one of peat soil and paddy soil.

[0011] Preferably, the organic matter content of the organic fertilizer in step (3) is greater than or equal to 30%, and the effective nutrients N-P2O5-K2O are greater than or equal to 4%; the inorganic fertilizer is at least one of diammonium phosphate, potassium dihydrogen phosphate and zinc sulfate.

[0012] The present invention also provides an application of the rice husk char modified substrate suitable for multi-mode rice seedling raising, wherein the rice husk char modified substrate is used for pot tray seedling raising or blanket tray seedling raising in wet seedling raising mode and dry seedling raising mode.

[0013] Preferably, the substrate used in the wet seedling raising mode for tray seedling raising includes modified rice husk charcoal and organic fertilizer; the mass ratio of the modified rice husk charcoal to the organic fertilizer is 80-90:10-20.

[0014] Preferably, the substrate used in the wet seedling raising mode for tray seedling raising includes modified rice husk charcoal, peat moss, and organic fertilizer; the mass ratio of the modified rice husk charcoal, peat moss, and organic fertilizer is 1-2:1-2:1-2.

[0015] Preferably, the substrate used in the tray seedling raising under the dry seedling raising mode includes modified rice husk charcoal, peat moss, and organic fertilizer; the mass ratio of the modified rice husk charcoal, peat moss, and organic fertilizer is 1-2:1-2:1-2.

[0016] Preferably, the substrate used in the tray seedling raising under the dry seedling raising mode includes modified rice husk charcoal and organic fertilizer; the mass ratio of the modified rice husk charcoal to the organic fertilizer is 1-2:1-2.

[0017] Preferably, during the seedling raising process, a mixed solution of ferrous sulfate and ammonium sulfate is sprayed to improve the leaf yellowing problem; the mass concentration of ferrous sulfate in the mixed solution is 0.1-0.15%, and the mass concentration of ammonium sulfate is 0.1-0.15%.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention provides a method for preparing and applying a rice husk charcoal-modified substrate suitable for multi-mode rice seedling raising. The method involves first soaking the rice husk charcoal in water, then soaking it in a mixed solution of citric acid and ammonium sulfate, and finally air-drying the rice husk charcoal to obtain modified rice husk charcoal. The modification method of this invention is simple, and the resulting modified rice husk charcoal is non-sticky, does not clump, and has a uniform color. At this stage, the content of alkaloids, organic acids, benzene compounds, organic heterocyclic compounds, lipids, and lipid analogs in the rice husk charcoal is significantly reduced, making it suitable for preparing rice seedling raising substrates. By mixing the above-mentioned modified rice husk charcoal with different fertilizers, rice husk charcoal-modified substrates suitable for rice seedling raising in different modes can be obtained. The rice husk charcoal-modified substrate prepared using this invention can be used not only in tray seedling raising but also has good seedling rolling effect in blanket tray seedling raising. Attached Figure Description

[0020] Figure 1 The effect of pot seedling raising in the wet seedling raising mode using the substrates of Formula 9 and Formula 10;

[0021] Figure 2 The effect of Formula 1 in the wet seedling raising mode in tray seedling raising;

[0022] Figure 3 The effect of Formula 2 in the wet seedling raising mode in tray seedling raising;

[0023] Figure 4 The effect of Formula 3 in the wet seedling raising mode in tray seedling raising;

[0024] Figure 5 The status of machine-transplanted and hand-transplanted seedlings in the moist seedling raising mode using formulas 2 and 3;

[0025] Figure 6 The effects of formulas 3 and 4 on the tray seedling raising in the moist seedling raising mode;

[0026] Figure 7 This describes the effects of seedling rolling and root coiling on the 4-layer mat tray.

[0027] Figure 8 This describes the effects of seedling rolling and root coiling on the 3-layer mat tray.

[0028] Figure 9 The effects of using different substrates on the 1-leaf stage of tray seedling raising under dry seedling raising mode;

[0029] Figure 10 The effects of using different substrates on the two-leaf stage of tray seedling raising under dry seedling raising mode;

[0030] Figure 11 The effect of rooting in the 2-leaf stage of tray seedling raising under dry seedling raising mode using different substrates;

[0031] Figure 12 The rolling effect of tray seedlings at the 3-leaf stage under dry seedling raising mode using different substrates;

[0032] Figure 13 The leaves can be restored to green color after being mixed and sprayed with 0.1% ferrous sulfate and 0.1% ammonium sulfate.

[0033] Figure 14 The effect of using formula 4 and formula 7 in pot seedling raising under dry seedling raising mode is shown. Detailed Implementation

[0034] This invention provides a method for preparing a rice husk charcoal-modified substrate suitable for multi-mode rice seedling raising, the steps of which are as follows:

[0035] (1) Soak the rice husk charcoal in clean water for 1 day, and then wash it once with clean water;

[0036] (2) Soak the cleaned rice husk charcoal in a mixed solution of citric acid and ammonium sulfate (citric acid mass concentration is 0.1% and ammonium sulfate mass concentration is 0.1%) for 1 day, and then soak it in a new mixed solution of citric acid and ammonium sulfate for 1 day the next day. Then air dry the rice husk charcoal to obtain modified rice husk charcoal.

[0037] (3) Mix the modified rice husk charcoal with fertilizer to obtain the rice husk charcoal modified substrate suitable for multi-mode rice seedling raising.

[0038] In a specific embodiment of the present invention, the rice husk charcoal is rice husk charcoal produced by Tianjin Yader Biomass Technology Co., Ltd.

[0039] The fertilizer mentioned in step (2) is at least one of peat moss, organic fertilizer, and inorganic fertilizer.

[0040] The organic fertilizer has an organic matter content of ≥30% and an effective nutrient content of ≥4% (N-P2O5-K2O). In a specific embodiment of the present invention, the organic fertilizer is an organic fertilizer produced by Guizhou Tiandifu Fertilizer Co., Ltd., product registration number: Qian Nongfei (2024) Zhunzi 1466.

[0041] The inorganic fertilizer is at least one of diammonium phosphate, potassium dihydrogen phosphate, and zinc sulfate.

[0042] The rice husk char modified substrate prepared by this invention is suitable for multi-mode rice seedling raising and can be used for pot tray or blanket tray seedling raising in wet seedling raising mode and dry seedling raising mode.

[0043] Specifically, the substrate used for tray seedling raising in the moist seedling raising mode includes modified rice husk charcoal and organic fertilizer; the mass ratio of modified rice husk charcoal to organic fertilizer is 80-90:10-20; the substrate used for blanket tray seedling raising in the moist seedling raising mode includes modified rice husk charcoal, peat moss, and organic fertilizer; the mass ratio of modified rice husk charcoal, peat moss, and organic fertilizer is 1-2:1-2:1-2; the substrate used for blanket tray seedling raising in the dry seedling raising mode includes modified rice husk charcoal, peat moss, and organic fertilizer; the mass ratio of modified rice husk charcoal, peat moss, and organic fertilizer is 1-2:1-2:1-2; the substrate used for tray seedling raising in the dry seedling raising mode includes modified rice husk charcoal and organic fertilizer; the mass ratio of modified rice husk charcoal to organic fertilizer is 1-2:1-2.

[0044] The present invention will be further described below with reference to the embodiments.

[0045] Example 1

[0046] A method for preparing modified rice husk charcoal, comprising the following steps:

[0047] (1) Soak the rice husk charcoal in clean water for 1 day, and then wash it once with clean water;

[0048] (2) Soak the cleaned rice husk charcoal in a mixed solution of citric acid and ammonium sulfate (the mass concentration of citric acid is 0.1% and the mass concentration of ammonium sulfate is 0.1%) for 1 day. Replace the solution with a new mixed solution of citric acid and ammonium sulfate and soak for another day. Then air dry the rice husk charcoal to obtain modified rice husk charcoal.

[0049] Table 1 shows the classification and proportion of metabolites in rice husk charcoal.

[0050] Table 1

[0051] Classification number percentage Alkaloids and their derivatives 63 2.87% benzene compounds 255 11.63% Hydrocarbons 5 0.23% Lignans, neolignans and related compounds 19 0.87% Lipids and lipid analogues 574 26.17% Nucleosides, nucleotides and their analogues 33 1.50% Organic acids and their derivatives 350 15.96% Nitrogen-containing organic compounds 23 1.05% oxygen-containing organic compounds 167 7.62% Halogenated organic compounds 12 0.55% organic heterocyclic compounds 430 19.61% sulfur-containing organic compounds 21 0.96% Phenylpropionic acid and polyketide compounds 227 10.35% other 14 0.64%

[0052] The types of compounds contained in modified and unmodified rice husk char are shown in Table 2.

[0053] Table 2

[0054] compound name Primary Classification Secondary classification Level 3 classification Sophora alkaloids Alkaloids and their derivatives Lupin alkaloids Matrine alkaloids Dihydrotanshinone I lipids and lipid molecules Isopentenyl ester Diterpenoids stearamide Organic acids and their derivatives Formicimonic acid and its derivatives Formic acid Octadecenoic acid (trans-6) / trans-rockapinic acid (C18:1T) lipids and lipid molecules fatty acyls fatty acids and compounds azelaic acid lipids and lipid molecules fatty acyls fatty acids and compounds Eicicoenoic acid (cis-11) lipids and lipid molecules fatty acyls fatty acids and compounds Octadectopadienoic acid (cis-9,12) / linoleic acid lipids and lipid molecules fatty acyls Linolenic acid and its derivatives Neocryptotanshinone lipids and lipid molecules Isopentenyl ester Diterpenoids Cyclic (L-prolyl-L-valine) Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues caffeic acid Phenylpropionic acid derivatives and polyketides Cinnamic acid and its derivatives Hydroxycinnamic acid and its derivatives 2-Heptyl-4-hydroxyquinoline 1-oxide organic heterocyclic compounds Quinoline and its derivatives 4-Hydroxy-2-alkylquinoline Oleic acid lipids and lipid molecules fatty acyls fatty acids and compounds o-Carboxybenzaldehyde benzene compounds Benzene and its substituted derivatives Benzoic acid and its derivatives 4-Hydroxyproline Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues p-Hydroxybenzaldehyde Organic oxygen compounds Organic oxygen compounds carbonyl compounds benzothiazolium organic heterocyclic compounds benzothiazoles _ 1-Palmyl-sn-glycerol-3-phosphocholine lipids and lipid molecules Glycerol phospholipids glycerophosphate choline Cyclic (L-prolyl-L-leucyl) Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues Acetylsalicylic acid benzene compounds Benzene and its substituted derivatives Benzoic acid and its derivatives Tetrahydropyrimidine Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues clove acid benzene compounds Benzene and its substituted derivatives Benzoic acid and its derivatives N6,N6-dimethyladenosine Nucleosides, nucleotides and analogues Purine nucleosides _ L-xylitol Organic oxygen compounds Organic oxygen compounds carbohydrates and carbohydrate compounds Glycosylated valine Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues Artemisinic acid lipids and lipid molecules Isopentenyl ester Sesquiterpenes 7-O-methylrosmarinicol lipids and lipid molecules Isopentenyl ester Terpenoids Artemether lipids and lipid molecules Isopentenyl ester Sesquiterpenes Cinchona acid Organic oxygen compounds Organic oxygen compounds alcohols and polyols Thousand-layer paper A Phenylpropionic acid derivatives and polyketides Flavonoids O-methylated flavonoids 6-Shogaol benzene compounds Phenols Methoxyphenols Glycosylmethionine Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues L-Leucine Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues Demethoxyin Sicarin organic heterocyclic compounds Benzopyrans 1-Benzopyran Milk Tree Alkaloids benzene compounds Phenols Benzene glycols Methylsuccinic acid lipids and lipid molecules fatty acyls fatty acids and compounds 5,6-Dimethylbenzimidazole organic heterocyclic compounds Benzimidazoles _ L-Asparagine Organic acids and their derivatives Carboxylic acids and their derivatives Amino acids, peptides and analogues Purple Butea Phenylpropionic acid derivatives and polyketides Straight-chain 1,3-diarylpropane Chalcone and dihydrochalcone

[0055] The results of the metabolomics analysis comparing modified and unmodified rice husk char are shown in Table 3. The steps of the metabolomics analysis are as follows:

[0056] (1) Take 1g of sample, place it in an EP tube, and add 1000ul of 80% methanol aqueous solution;

[0057] (2) Vortex oscillation, let stand in ice bath for 5 min, centrifuge at 15000g and 4℃ for 15 min;

[0058] (3) Take the supernatant and centrifuge it again at 15000g and 4℃ for 20min;

[0059] (4) Take the supernatant and freeze-dry it;

[0060] (5) Dissolve in 200 μL of 10% methanol solution and analyze by LC-MS.

[0061] The secondary mass spectra obtained from metabolomics experiments were compared with databases (KEGG, HMDB, LIPID MAPS), and the similarity was calculated using the dot product algorithm, with scores ranging from 0 to 1.

[0062] Identification levels: Level 1 is confirmatory identification, completely consistent with the actual standard; Level 2 is speculative identification, no standard is available; Level 3 is speculative structural category, only the compound category can be inferred, not the precise rice molecule; Level 4 is only the molecular formula is known, the structure is unknown; Level 5 is completely unknown.

[0063] Table 3

[0064] compound name Match score Level of identification chromatographic column Unmodified rice husk charcoal.aver Modified rice husk charcoal.aver log2(modified rice husk charcoal / unmodified rice husk charcoal) Sophora alkaloids 1.00 1 C18 8589583.6 1589633.4 -2.43 Dihydrotanshinone I 1.00 1 C18 1241897.9 402504.28 -1.62 stearamide 0.98 1 C18 254627445 120664870 -1.07 Octadecenoic acid (trans-6) / trans-rockapinic acid (C18:1T) 0.97 1 C18 15458341 4399416 -1.81 azelaic acid 0.96 1 C18 49428799249.97 12970446276.09 -1.93 Eicicoenoic acid (cis-11) 0.94 1 C18 375751.82 170832.06 -1.13 Octadectopadienoic acid (cis-9,12) / linoleic acid 0.93 1 C18 22930609 4924695.1 -2.21 Neocryptotanshinone 0.93 1 C18 19904468 5440130.6 -1.87 Cyclic (L-prolyl-L-valine) 0.93 1 C18 491036976 202887201 -1.27 caffeic acid 0.91 1 C18 2965577594.66 202031225 -3.87 2-Heptyl-4-hydroxyquinoline 1-oxide 0.91 1 C18 44185853 10722456 -2.04 Oleic acid 0.91 1 C18 6521852108.35 2696032041.14 -1.27 o-Carboxybenzaldehyde 0.88 1 C18 173260412 37954350 -2.19 4-Hydroxyproline 0.88 1 C18 74019676 32076809 -1.2 p-Hydroxybenzaldehyde 0.87 1 C18 17472033256.99 2234087441.25 -2.96 benzothiazolium 0.87 1 C18 857902055 266427628 -1.68 1-Palmyl-sn-glycerol-3-phosphocholine 0.87 1 C18 19908516 7507084.1 -1.4 Cyclic (L-prolyl-L-leucyl) 0.87 1 C18 669922812 322544530 -1.05 Acetylsalicylic acid 0.85 1 C18 2734110917.81 915097624 -1.57 Tetrahydropyrimidine 0.82 1 C18 12416487 3273260.4 -1.92 clove acid 0.79 1 C18 1184587432.99 65632955 -4.17 N6,N6-dimethyladenosine 0.79 1 C18 5836189.2 2343541.7 -1.31 L-xylitol 0.78 1 C18 6974345.3 1980060.2 -1.81 Glycosylated valine 0.77 1 C18 70476989 26895367 -1.38 Artemisinic acid 0.76 1 C18 2618567982.87 1266901406 -1.04 7-O-methylrosmarinicol 0.75 1 C18 44125843 15085096 -1.54 Artemether 0.75 1 C18 17717076219.08 7943058790.42 -1.15 Cinchona acid 0.74 1 C18 422566445 201474102 -1.06 Thousand-layer paper A 0.73 1 C18 330354459 46878359 -2.81 6-Shogaol 0.73 1 C18 1848546618.36 407013169 -2.18 Glycosylmethionine 0.73 1 C18 18323196 7690776.4 -1.25 L-Leucine 0.72 1 C18 4753232.5 1423506.3 -1.73 Demethoxyin Sicarin 0.72 1 C18 58698549 24310207 -1.27 Milk Tree Alkaloids 0.71 1 C18 6317565 867503.53 -2.86 Methylsuccinic acid 0.71 1 C18 41246937 9067180.5 -2.18 5,6-Dimethylbenzimidazole 0.70 1 C18 8833304.3 1303965.3 -2.76 L-Asparagine 0.70 1 C18 117463101 19596029 -2.58 Purple Butea 0.70 1 C18 15540601 4654949.7 -1.73

[0065] As shown in Tables 2 and 3, rice husk charcoal contains a high proportion of benzene compounds, lipids and lipid analogs, organic acids and their derivatives, and organic heterocyclic compounds, which are potential inhibitors of rice growth. In contrast, modified rice husk charcoal contains significantly reduced levels of alkaloids (such as sophoridine, which has allelopathic inhibitory effects), organic acids, benzene compounds, organic heterocyclic compounds, lipids, and lipid analogs.

[0066] Example 2

[0067] A rice husk char-modified substrate for rice seedling cultivation, using modified rice husk char prepared in Example 1, unmodified rice husk char, or paddy soil as raw materials, is mixed with different fertilizers. The specific formula is as follows:

[0068] Formula 1: Mix modified rice husk charcoal and peat moss in a mass ratio of 1:1 to obtain a mixture. Then, mix the mixture with diammonium phosphate, potassium dihydrogen phosphate and zinc sulfate in a mass ratio of 95%, 3%, 1.5% and 0.5% to obtain a seedling substrate.

[0069] Formula 2: Mix modified rice husk charcoal and peat moss in a mass ratio of 3:1 to obtain a mixture. Mix the mixture with organic fertilizer in a mass ratio of 3:1 to obtain a seedling substrate.

[0070] Formula 3: Mix modified rice husk charcoal and organic fertilizer at a mass ratio of 85% and 15% to obtain a seedling substrate;

[0071] Formula 4: Mix modified rice husk charcoal, peat moss, and organic fertilizer in a mass ratio of 1:1:1 to obtain the seedling substrate;

[0072] Formula 5: Mix modified rice husk charcoal, peat moss and organic fertilizer in a mass ratio of 1:1:1, and then mix the mixture with diammonium phosphate, potassium dihydrogen phosphate and zinc sulfate in a mass ratio of 95%, 3%, 1.5% and 0.5% to obtain the seedling substrate;

[0073] Formula 6: Mix modified rice husk charcoal, peat moss and organic fertilizer in a mass ratio of 1:1:1, and then mix the mixture with sterilized paddy field soil (sterilized by sun exposure) in a mass ratio of 1:1 to obtain the seedling substrate;

[0074] Formula 7: Mix modified rice husk charcoal and organic fertilizer at a mass ratio of 1:1 to prepare a seedling substrate.

[0075] Formula 8: Sterilized paddy soil (sterilized by sun exposure) and organic fertilizer are mixed at a mass ratio of 3:1 to obtain the seedling substrate;

[0076] Formula 9: Mix unmodified rice husk charcoal and organic fertilizer at a mass ratio of 85% and 15% to obtain a seedling substrate;

[0077] Formula 10: Mix unmodified rice husk charcoal, peat moss, and organic fertilizer in a mass ratio of 1:1:1 to obtain the seedling substrate.

[0078] Experiment 1: Using substrates of formulas 9 and 10 and 448-well seed trays, seeding was carried out using a continuous seeder. 2-3 seeds (Zhuxiang 19 rice seeds, hereinafter the same) were sown per well in a moist seedling raising mode. The sowing procedure was: sowing the substrate – sowing – covering with soil – watering. Before emergence, the temperature was controlled to be no higher than 35℃. From the 1-leaf and 1-core stage to the 2-leaf and 1-core stage, the temperature was controlled at 22-25℃, and at the 3-leaf stage, it was controlled at 18-22℃. The results showed that seedlings of formula 9 grew slowly, and root growth was inhibited. Rice seeds of formula 10 germinated uniformly, but the rice seedlings emerged unevenly, the leaves turned yellow, and eventually the entire plant withered and died. The results are as follows: Figure 1 It can be seen that unmodified rice husk charcoal cannot be directly used to prepare rice seedling substrate.

[0079] Experiment 2: Comparison of the effects of different formulated charcoal substrates in tray seedling raising under the moist seedling raising mode.

[0080] Using seedling substrates of formulas 1, 2, and 3, seedlings were raised in pots using the moist seedling raising method described in Experiment 1. The results are as follows: Figure 2-4 .

[0081] from Figures 2-4It can be seen that the seedling substrates of Formula 1, Formula 2, and Formula 3 all resulted in normal seedling emergence, with well-developed root systems, good root development, and no issues of substrate floating or significant loss. The experimental results demonstrate that in the moist seedling raising mode, using only biochar as the medium and adding a small amount of organic fertilizer is sufficient to cultivate high-quality seedlings. Considering both cost and the ease of substrate preparation, Formula 3 is more suitable for tray seedling raising in the moist seedling raising mode.

[0082] Formulas 2 and 3 were used in a seedling demonstration project in Yashui Town, Huishui County, Qiannan Prefecture, Guizhou Province, covering a total area of ​​4 mu (approximately 0.67 hectares). The demonstration used a tray planter, with both the substrate and covering soil using the same formula. After covering, a misting system was added to moisten the surface soil. The trays were then stacked for a darkening process. Before placing the trays, the paddy field was leveled, ensuring no water layer remained. The trays were inserted into the mud, and trenches were dug on both sides of each tray, which were then covered with a single layer of non-woven fabric. Figure 5 As shown, the seedlings used for machine transplanting are of good quality, with many and thick roots, while the seedlings used for hand transplanting are also of good quality, with well-developed root systems and many white roots.

[0083] Experiment 3: Comparison of the effects of different substrate formulations in tray seedling raising under the moist seedling raising mode.

[0084] Using seedling substrates formulated with formulas 3 and 4, and a automated seeder, seedlings were sown in moist seedling trays using 0.75 kg of substrate and 70 g of rice seeds per tray. The sowing procedure was: sowing the substrate, sowing, covering with soil, and watering. Before emergence, the temperature was controlled to not exceed 35℃. From the 1-leaf and 1-core stage to the 2-leaf and 1-core stage, the temperature was controlled at 22-25℃. At the 3-leaf stage, the temperature was controlled at 18-22℃. Results were as follows... Figure 6 Formula 4's effect on seedling rolling and root coiling in the tray is as follows: Figure 7 Formula 3's effect on seedling rolling and root coiling is as follows: Figure 8 .

[0085] from Figures 6-8 It can be seen that both Formula 3 and Formula 4 produce normal seedlings using their respective seedling substrates. However, Formula 4 has better root-binding and seedling-rolling effects and does not cause the seedling trays to fall apart. In contrast, Formula 3 is more prone to seedling tray falling apart, and its root-binding effect is not as good as that of Formula 4. Therefore, in agricultural production, under the wet seedling raising mode, Formula 4 has a better seedling raising effect when using the blanket tray method.

[0086] Experiment 4: Comparison of the effects of different substrate formulations in tray seedling raising under dry seedling raising mode

[0087] Formulas 4, 5, 6, 7, and 8 were used for sowing using a continuous seeder. Each tray contained 0.75 kg of substrate and 70 g of rice seeds in a dry seedling raising model. The sowing procedure was: sowing substrate – sowing – covering with soil – watering. Before emergence, the temperature was controlled to not exceed 35℃. From the 1-leaf and 1-core stage to the 2-leaf and 1-core stage, the temperature was controlled at 22-25℃, and at the 3-leaf stage, it was controlled at 18-22℃. The effects of different substrate formulas on tray seedling raising at the 1-leaf stage are shown below. Figure 9 The effects of different substrate formulations in tray seedling raising at the 2-leaf stage are as follows: Figure 10 The root-forming effects of formulas 4, 6, 7, and 8 at the 3-leaf stage are as follows: Figure 11 The seedling-rolling effects of formulas 4, 6, and 7 are as follows: Figure 12 .

[0088] Figure 9 At the one-leaf stage, the excessive fertilizer in formula 5 caused the seedlings to turn yellow, while the seedlings of formulas 4, 6, 7 and 8 were of comparable quality. Figure 10 When the seedlings of Formula 5 were in the 2-leaf stage, they turned yellow and were short and grew slowly, while the seedlings of Formula 4 and Formula 6 grew faster and were taller. Figure 11 When the 3-leaf stage was observed, formulas 4, 6, 7, and 8 all showed good root-binding effects. Figure 12 The results showed that seedlings from formulas 4 and 6 could be rolled up normally, while those from formula 7 were prone to falling apart.

[0089] at the same time Figure 11 The results showed that seedlings from formulas 4, 6, and 7 were more yellow than those from formula 8. Applying a mixture of 0.1% ferrous sulfate and 0.1% ammonium sulfate solution, spraying until the leaves dripped, quickly restored the leaves to their green color. Initially, green spots appeared on the yellowed leaves; subsequently, these spots gradually enlarged and merged, eventually restoring the entire leaf to its green color. The results were as follows... Figure 13 .

[0090] Experiment 5: Comparison of the effects of different substrate formulations in tray seedling raising under dry seedling raising mode.

[0091] Using formulas 4 and 7 and 448-well seedling trays, seeding was carried out using a continuous seeder, with 2-3 seeds sown per well in a dry seedling raising mode. The sowing procedure was: sowing the bottom soil - sowing - covering with soil - watering. Before emergence, the temperature was controlled not to exceed 35℃. From the 1-leaf and 1-bud stage to the 2-leaf and 1-bud stage, the temperature was controlled at 22-25℃, and when the seedlings had 3 leaves, the temperature was controlled at 18-22℃. The results were as follows: Figure 14 .

[0092] from Figure 14 It is evident that both Formula 4 and Formula 7 have good effects in pot seedling raising, and the rooting effect of seedlings in independent pots is good. Considering the ease of formula preparation, Formula 7 is selected for pot seedling raising under the dry seedling raising mode.

[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a rice hull charcoal-modified substrate suitable for multi-mode rice seedling raising, characterized by, It comprises the following steps: (1) soaking rice husk charcoal in clean water for 1-2 days, and then washing it with clean water for 1-3 times; (2) soaking the washed rice husk charcoal in a mixed solution of citric acid and ammonium sulfate for 1-2 days, repeating the soaking for 2-3 times, and then drying the rice husk charcoal to obtain modified rice husk charcoal; The modified rice husk charcoal is not sticky and does not form clumps, and has uniform color, and the alkaloids, organic acids, benzene compounds, organic heterocyclic compounds, lipids and lipid analogues in the rice husk charcoal are significantly reduced, which is used to configure a rice seedling raising substrate; (3) mixing the modified rice husk charcoal with fertilizer and / or substrate to obtain the rice husk charcoal modified substrate suitable for multi-mode rice seedling raising; In the mixed solution of citric acid and ammonium sulfate in step (2), the mass concentration of citric acid is 0.1%, and the mass concentration of ammonium sulfate is 0.1%; In step (3), the fertilizer is at least one of organic fertilizer and inorganic fertilizer; and the substrate is at least one of grass charcoal soil and paddy soil; In step (3), the organic matter content of the organic fertilizer is ≥30%, and the effective nutrient N-P2O5-K2O is ≥4%; and the inorganic fertilizer is at least one of diammonium phosphate, potassium dihydrogen phosphate and zinc sulfate.

2. The use of the rice hull charcoal-modified substrate of claim 1 for multi-mode rice seedling raising, characterized in that, The rice husk charcoal modified substrate is used for pot seedling raising or blanket seedling raising in wet seedling raising mode and dry seedling raising mode.

3. The use of rice hull charcoal-modified substrate for multi-mode rice seedling raising according to claim 2, characterized in that, The substrate used in the pot seedling raising in the wet seedling raising mode comprises modified rice husk charcoal and organic fertilizer; and the mass ratio of the modified rice husk charcoal to the organic fertilizer is 80-90:10-20.

4. The use of rice hull charcoal-modified substrate for multi-mode rice seedling raising according to claim 2, characterized in that, The substrate used in the blanket seedling raising in the wet seedling raising mode comprises modified rice husk charcoal, grass charcoal soil and organic fertilizer; and the mass ratio of the modified rice husk charcoal to the grass charcoal soil to the organic fertilizer is 1-2:1-2:1-2.

5. The use of rice hull charcoal-modified substrate for multi-mode rice seedling raising according to claim 2, characterized in that, The substrate used in the blanket seedling raising in the dry seedling raising mode comprises modified rice husk charcoal, grass charcoal soil and organic fertilizer; and the mass ratio of the modified rice husk charcoal to the grass charcoal soil to the organic fertilizer is 1-2:1-2:1-2.

6. The use of rice hull charcoal-modified substrate for multi-mode rice seedling raising according to claim 2, characterized in that, The substrate used in the pot seedling raising in the dry seedling raising mode comprises modified rice husk charcoal and organic fertilizer; and the mass ratio of the modified rice husk charcoal to the organic fertilizer is 1-2:1-2.

7. The use of rice hull charcoal-modified substrate for multi-mode rice seedling raising according to claim 2, characterized in that, In the seedling raising process, a mixed solution of ferrous sulfate and ammonium sulfate is sprayed to improve the leaf yellowing problem; and the mass concentration of ferrous sulfate in the mixed solution is 0.1-0.15%, and the mass concentration of ammonium sulfate is 0.1-0.15%.

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