A method for increasing the proportion of large-diameter soil aggregates based on straw utilization

Abstract

The application provides a method for increasing the proportion of large-diameter soil aggregates based on straw utilization, and relates to the tobacco planting technical field.The method comprises the following steps: S1: crushing field straw and stubble by using a crusher to obtain crushed materials; S2: mixing the crushed materials with organic fertilizer and water, and centrally stacking on the surface of soil to pre-ferment to obtain mixed materials, then spraying bacteria liquid 1, covering a film, and carrying out aerobic fermentation to obtain fermented materials; S3: removing the film, uniformly spreading the fermented materials, spraying bacteria liquid 2, using a powder ridge deep plough to plough, and carrying out water irrigation treatment to carry out anaerobic fermentation.The method has a greater influence on the powder clay aggregates and the medium aggregates in the plough layer soil, and has a smaller influence on the large aggregates; for the plough bottom layer soil, the method reduces the proportion of the powder clay aggregates, realizes the expansion of the small-diameter aggregates, improves the proportion of the medium and large aggregates, and is beneficial to expanding the depth of the plough layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tobacco planting, in particular to a method for increasing the proportion of large-diameter soil aggregates based on straw utilization. BACKGROUND

[0002] Tobacco is a crop that is not suitable for continuous cropping. Long-term continuous cropping of tobacco as a single crop will lead to an increase in the abundance of soil pathogenic fungi, accelerate the spread of diseases, and result in reduced quality and even reduced yield of tobacco leaves. Therefore, tobacco is generally planted in a crop rotation system, and water-flood rotation (tobacco-rice rotation) is one of the main methods. However, as the rotation period of tobacco and rice is extended, the soil bulk density tends to increase significantly, while the soil capillary void fraction and total void fraction decrease significantly. The stability of large aggregates decreases, and the degree of soil aggregate disintegration increases. Small particles such as silt and clay aggregates continuously accumulate in the lower layer under the action of gravity. Combined with the improper use of fertilizers and the continuous compaction of large machinery, the problem of the continuous shallowing of the plough layer and the upward movement of the plough pan becomes increasingly serious.

[0003] To improve soil structure, the existing patent CN 111393222A discloses a method for increasing soil aggregates, which uses a soil conditioner comprising 0-60 parts of organic fertilizer, 0-60 parts of gypsum powder, 10-30 parts of modified bentonite, 5-30 parts of humic acid, 1-5 parts of water retaining agent and 0.6-3 parts of inorganic salt. The method can solve the problem of soil compaction, change the carbon structure of the soil, increase the number and stability of water-stable large aggregates in the soil, improve the physical properties of the soil, and the used substances are environmentally friendly and easy to degrade. Patent CN 111908977A discloses a soil conditioner based on biochar and ammoniated straw, which comprises 15-20 parts of biochar, 35-45 parts of ammoniated straw, 0.02-0.04 parts of fermentation bacteria, 5-10 parts of oil residue, 5-10 parts of bacterial residue, 5-10 parts of fruit residue, 0.6-0.8 parts of urea, 1.8-2.2 parts of calcium sulfate and 5-10 parts of wood vinegar. The present application can quickly increase the organic matter content of the soil, promote the formation of soil aggregates, form a soil structure with reasonable texture, improve the soil aeration and water permeability, establish a rainwater infiltration drainage channel in the soil of the land, balance the carbonate and bicarbonate ions in the soil, reduce the pH of the soil, and improve the fertility of the newly created land. At the same time, the present application has the effects of carbon sequestration and emission reduction. Patent CN 116286011 A discloses an in-situ soil remediation reagent, which comprises in-situ soil micro-aggregates, in-situ soil silt and clay aggregates, soil stock solution, yeast extract, pancreatic proteose peptone, sodium chloride, green pyocyanin, human heart fruit tree waste branch coarse emulsion and ethylenediaminetetraacetic acid solution. The in-situ soil remediation reagent promotes soil particle aggregation to solve the problem of excessive proportion of small-diameter soil aggregates in the soil, and improves the soil structure, increases the soil nutrient content and water retention capacity.

[0004] All of the above methods can promote soil particle aggregation, but they have some limitations in improving the composition of soil aggregates in tobacco-rice rotation. In addition, the pretreatment process of acidification before use of bentonite in patent CN 111393222A is cumbersome and not conducive to large-scale production in the field; the ammoniation of straw in patent CN 111393222A also requires certain site and time requirements; the soil improvement scheme provided by CN 116286011 A mainly uses Pseudomonas aeruginosa, which is an opportunistic pathogen and can easily infect humans under certain conditions, thus lacking certain safety. At the same time, due to its simple structure, it can easily affect the diversity and stability of the microbial community under the original soil structure.

[0005] Soil aggregates are the basic units of soil structure, and their composition and distribution are important indicators of good soil aggregate structure. The size, distribution, and stability of soil aggregates determine the cycling of soil nutrients and microbial activity, thus affecting soil biogeochemical reactions. In tobacco-rice rotation areas, high land multiple cropping indices, unreasonable fertilizer application, and continuous cropping lead to changes in the particle size distribution of soil aggregates and a decline in their stability, resulting in a heavy, compacted texture that severely limits rice yield and the quality and characteristics of tobacco leaves. Therefore, improving soil aggregate stability is of great significance for improving soil physicochemical properties, cultivating soil suitable for year-round growth of flue-cured tobacco and rice, and promoting high-quality and high-yield crops for both crops. Currently, straw return to the field is the main method of soil improvement in tobacco-rice rotation areas. Straw return can improve soil aggregate structure and physicochemical properties to a certain extent. However, straw return alone requires a long time and has a slow effect. Summary of the Invention

[0006] This invention provides a method for increasing the proportion of large-diameter soil aggregates based on straw utilization, the purpose of which is to solve the aforementioned problems existing in the background technology.

[0007] To achieve the above objectives, embodiments of the present invention provide a method for increasing the proportion of large-diameter soil aggregates based on straw utilization, comprising the following steps:

[0008] S1: Use a crusher to crush straw and stubble in the field to obtain crushed materials;

[0009] S2: The crushed material is thoroughly mixed with organic fertilizer and water, piled on the soil surface for pre-fermentation to obtain a mixture, then sprayed with bacterial solution 1 and covered with film for heat preservation and aerobic fermentation to obtain fermented product;

[0010] S3: Remove the covering film, spread the fermented material evenly, spray with bacterial solution 2, then use a deep tillage machine to plow and irrigate to carry out anaerobic fermentation.

[0011] Preferably, the mass ratio of the pulverized material to the organic fertilizer and water is 15-17:6-9:1-2.

[0012] Preferably, the organic fertilizer is composed of cow / sheep manure, humic acid, calcium oxide, and magnesium silicate in a mass ratio of 15-17:2-3:1-1.5:0.5-1.

[0013] Preferably, the bacterial agent composition in the bacterial solution 1 is as follows: the ratio of Trichoderma longibranchii: Penicillium oxalate: Streptomyces amylase subsp. slate: Proteobacterium chrysosporum: Bacillus subtilis: Cellulosum humicum is 1-2:1-2:1-2:1-2:1-2:1-2, and the viable count / g is >300 million.

[0014] Preferably, the bacterial agent in the bacterial solution 1 is prepared by mixing the bacterial agent and water at a mass ratio of 0.8 to 1.2:100; the mass ratio of the mixed material to the sprayed bacterial solution 1 is 10 to 12:0.8 to 1.2.

[0015] Preferably, the bacterial agent composition in the bacterial solution 2 is: *Cryptospira harzianum*: *Candida krusei*: *Actinomyces succinate* in a ratio of 1-1.5:0.8-1:1-1.5, with a viable count / g > 300 million.

[0016] Preferably, the bacterial agent and water in the bacterial solution 2 are prepared by mass ratio of 0.8-1.2:49-51; the mass ratio of the mixed material to the sprayed bacterial solution 2 is 8-10:0.8-1.2.

[0017] Preferably, the pre-fermentation time is 2 to 3 days; the aerobic fermentation time is 30 to 50 days.

[0018] Preferably, the tillage depth is 40cm; the irrigation process uses 6 tons of water per mu (approximately 0.067 hectares); and the anaerobic fermentation time is 70-80 days.

[0019] Preferably, the particle size of the large-particle soil aggregate is >0.25cm.

[0020] mechanism

[0021] This invention innovatively employs a two-stage straw degradation method: the first stage, under aerobic conditions, utilizes microorganisms in an inoculant to initially degrade large molecules into smaller ones; the second stage, under anaerobic conditions, involves secondary fermentation, which increases the degradation rate and allows nutrients released from straw degradation and microbial metabolism, along with small soil aggregates and other cementing substances, to naturally form larger aggregates in the soil. The well-rotted cow / sheep manure in the organic fertilizer formula supplements and balances other elements in the soil, while humic acid and calcium oxide primarily regulate pH. Magnesium silicate, in addition to providing nutrients, also serves as a medium for microbial adhesion. A deep tillage machine is then used to drive the aerobically fermented material into the soil to a depth of 40cm, applying the returned material to the deeper soil layers. Subsequent fermentation promotes the formation of micro-aggregates, which in turn promotes the formation of medium and large (>0.25cm) aggregates.

[0022] The above-described solution of the present invention has the following beneficial effects:

[0023] (1) This invention utilizes the decomposition of microorganisms to break down straw into polysaccharides, glucose, and other substances, releasing residual nutrients to replenish soil organic carbon, available phosphorus, and available potassium. Various bacteria and fungi utilize organic acids and small-molecule polysaccharides secreted from straw, glucose and small-molecule polysaccharides released from straw decomposition, inorganic cementing substances in the soil (such as iron oxide, aluminum oxide, and silicates), and fungal hyphae to collectively cement the soil, forming micro-aggregates and macro-aggregates, thereby increasing the size of soil aggregates. The substances in the organic fertilizer formula mainly enrich the content of other organic matter in the soil and regulate soil pH, while silicates and other substances provide attachment sites for microorganisms.

[0024] (2) The method of deep burial after straw crushing in this invention solves the problems of overwintering pests in straw from the aspects of physical crushing and creating an anaerobic environment. At the same time, the antibiotics produced by various bacteria are beneficial to enriching soil organic matter and inhibiting the growth of harmful bacteria. The CO2 produced by Candidakrusei in the anaerobic environment is beneficial to further creating an anaerobic environment. In combination with Actinobacillus succinogenes, it is beneficial to its decomposition of cellulose.

[0025] (3) The microbial strains used in the formulation of this invention are all widely found in soil or animal digestive organs, exhibiting a certain degree of adaptability to the soil environment. Furthermore, the diverse strain structure is beneficial for improving the microbial diversity and stability in the soil. For example, *Phanerochaete chrysosporium* has a good ability to degrade lignin, providing support for the complete decomposition of the substrate. The enzymes and acidic substances secreted by *Penicillium oxalate* play a certain promoting role in balancing soil pH and promoting cell wall (mainly cellulose) decomposition.

[0026] (4) The deep tillage machine used in this invention can drive the primary fermented material spread on the soil surface into a depth of about 30cm from the ground. Through secondary fermentation, large soil aggregates are formed in the deep tillage layer. The rich microbial composition improves the stability of the aggregates, thereby alleviating the problem of the plow pan moving upward with the number of tillages. Detailed Implementation

[0027] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.

[0028] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0029] Unless otherwise specified, all raw materials, microbial agents, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0030] This invention addresses existing problems by providing a method for increasing the proportion of large-diameter soil aggregates based on straw utilization, comprising the following steps:

[0031] S1: Use a crusher to crush straw and stubble in the field to obtain crushed materials;

[0032] S2: The crushed material is thoroughly mixed with organic fertilizer and water, piled on the soil surface for pre-fermentation to obtain a mixture, then sprayed with bacterial solution 1 and covered with film for heat preservation and aerobic fermentation to obtain fermented product;

[0033] S3: Remove the covering film, spread the fermented material evenly, spray with bacterial solution 2, then use a deep tillage machine to plow and irrigate to carry out anaerobic fermentation.

[0034] Preferably, the mass ratio of the pulverized material to the organic fertilizer and water is 15-17:6-9:1-2.

[0035] Preferably, the organic fertilizer is composed of cow / sheep manure, humic acid, calcium oxide, and magnesium silicate in a mass ratio of 15-17:2-3:1-1.5:0.5-1.

[0036] Preferably, the bacterial agent composition in the bacterial solution 1 is as follows: the ratio of Trichoderma longibranchii: Penicillium oxalate: Streptomyces amylase subsp. slate: Proteobacterium chrysosporum: Bacillus subtilis: Cellulosum humicum is 1-2:1-2:1-2:1-2:1-2:1-2, and the viable count / g is >300 million.

[0037] Preferably, the bacterial agent in the bacterial solution 1 is prepared by mixing the bacterial agent and water at a mass ratio of 0.8 to 1.2:100; the mass ratio of the mixed material to the sprayed bacterial solution 1 is 10 to 12:0.8 to 1.2.

[0038] Preferably, the bacterial agent composition in the bacterial solution 2 is: *Cryptospira harzianum*: *Candida krusei*: *Actinomyces succinate* in a ratio of 1-1.5:0.8-1:1-1.5, with a viable count / g > 300 million.

[0039] Preferably, the bacterial agent and water in the bacterial solution 2 are prepared by mass ratio of 0.8-1.2:49-51; the mass ratio of the mixed material to the sprayed bacterial solution 2 is 8-10:0.8-1.2.

[0040] Preferably, the pre-fermentation time is 2 to 3 days; the aerobic fermentation time is 30 to 50 days.

[0041] Preferably, the tillage depth is 40cm; the irrigation process uses 6 tons of water per mu (approximately 0.067 hectares); and the anaerobic fermentation time is 70-80 days.

[0042] Preferably, the particle size of the large-particle soil aggregate is >0.25cm.

[0043] The experimental plots for the following embodiments and comparative examples of the present invention are as follows, and are explained in detail through the following implementation process.

[0044] 1. Test location:

[0045] Overview of the experimental site: Liuyang is located on the border of Hunan and Jiangxi provinces, in the northern part of eastern Hunan, at 27°51′-28°34′ north latitude and 113°10′-114°15′ east longitude. The experimental research was conducted in a tobacco-rice rotation field (113°22′2″, 28°17′17″) in Yong'an Town, Liuyang City, Changsha.

[0046] 2. Test duration:

[0047] The process begins uniformly on November 15th after the rice harvest and ends on March 15th, lasting a total of 4 months.

[0048] Example 1

[0049] A method for increasing the proportion of large-diameter soil aggregates based on straw utilization includes the following steps:

[0050] (1) Straw crushing: In the above-mentioned tobacco-rice rotation fields, after the straw is harvested, the straw and stubble in the field are crushed using a crusher;

[0051] (2) Aerobic fermentation: Mix the crushed materials, organic fertilizer, and warm water (25-30℃) in a mass ratio of 16:8:1, pile them on the soil surface for 2-3 days for pre-fermentation to obtain a mixture; then mix the dry powder of the microbial agent and water in a mass ratio of 1:100 to prepare a microbial solution, and spray it evenly on the surface of the mixture with a mass ratio of mixture to microbial solution of 10:1, cover with mulch film to keep warm and ferment for 1.5 months;

[0052] (3) Anaerobic fermentation: Remove the covering film, spread the fermented material from the previous step evenly, mix the dry powder of the inoculant with warm water (25-30℃) at a ratio of 1:50 to make a bacterial solution, spray it onto the fermented material from the previous step at a ratio of initial mixture: bacterial solution = 8:1, use a deep tillage machine to carry the fermented material into the ground to a depth of about 40cm; irrigate the field at a rate of 6 tons / acre, and wait for 2.5 months.

[0053] The microbial agent 1 consists of: *Trichoderma longifolia*: *Penicillium oxalate*: *Streptomyces amylase* subsp. *sclerotium*: *Procambarus chrysospora*: *Bacillus subtilis*: *Cellulosum humicum* = 1:1:1:1:1:1, with a viable count / g > 300 million; the microbial agent 2 consists of: *Cellulosum harzianum*: *Candida krusei*: *Actinomyces succinate* = 1:1:1, with a viable count / g > 300 million. The organic fertilizer is composed of cow / sheep manure, humic acid, calcium oxide, and magnesium silicate in a mass ratio of 16:2:1:1.

[0054] Comparative Example 1

[0055] There is no straw crushing process; the other steps are the same as in Example 1.

[0056] Comparative Example 2

[0057] The other steps are the same as in Example 1, except that bacterial solution 2 was not applied during the anaerobic fermentation process.

[0058] Comparative Example 3

[0059] The other steps are the same as in Example 1, except that anaerobic fermentation is not performed.

[0060] Comparative Example 4

[0061] The other steps are the same as in Example 1, except that only organic fertilizer is applied during aerobic fermentation and no anaerobic fermentation process is carried out.

[0062] Comparative Example 5

[0063] The other steps are the same as in Example 1, except that only the straw crushing process is performed.

[0064] In Example 1 and Comparative Examples 1-5 above, the deep tillage was carried out on December 30th, and the remaining procedures remained consistent. After the above treatment, soil was collected using a soil sampling column machine and divided into topsoil (0-20cm) and subsoil (20-40cm). The soil samples were then sieved and analyzed for soil aggregate composition using a wet sieving method, as detailed below:

[0065] 100g of soil was air-dried and placed on the top layer of a 5mm sieve (with 0.25mm, 0.053mm, and 0.02mm sieves assembled below the 2mm sieve). The water level in the bucket below the sieve was adjusted so that the soil sample in the top sieve was just submerged. Then, the soil was soaked in distilled water at room temperature for 10 minutes. The sieve was moved up and down 5cm, and this process was repeated 200 times within 10 minutes before collection. Powdered aggregates (0.02-0.053mm), micro-aggregates (0.053-0.25mm), medium-sized aggregates (0.25-2mm), and large aggregates (>2mm) were collected. The experimental results are shown in Tables 1 and 2 below.

[0066] Table 1 of the test results

[0067]

[0068] Table 2 of the test results

[0069]

[0070] As shown in Tables 1 and 2 above, in the topsoil, compared with Comparative Example 1, the soil microaggregates and silty aggregates in the treatment of Example 1 decreased by 5.94 g and 9.96 g, respectively, while the macroaggregates increased by only 3.70 g and the medium aggregates increased by 12.22 g. For the plow pan soil, the soil microaggregates and silty aggregates in the treatment of Example 1 decreased by 14.46 g and 31.56 g, respectively, while the macroaggregates increased by 12.40 g, the medium aggregates increased by 33.62 g, and the macroaggregates increased by 61.23%.

[0071] In summary, for topsoil, the treatment in Example 1 had a greater impact on silty aggregates and medium-sized aggregates, but a smaller impact on large aggregates. For plow pan soil, the treatment in Example 1 reduced the proportion of silty aggregates, increased the size of small aggregates, and increased the proportion of medium and large aggregates, which is beneficial for expanding the depth of the topsoil.

[0072] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 increasing the proportion of large-diameter soil aggregates based on straw utilization, characterized in that, Includes the following steps: S1: Use a crusher to crush straw and stubble in the field to obtain crushed materials; S2: The crushed material is thoroughly mixed with organic fertilizer and water, piled on the soil surface for pre-fermentation to obtain a mixture, then sprayed with bacterial solution 1 and covered with film for heat preservation and aerobic fermentation to obtain fermented product; S3: Remove the covering film, spread the fermented material evenly, spray bacterial solution 2, then use a deep tillage machine to plow and irrigate to carry out anaerobic fermentation. The bacterial agent composition of the bacterial solution 1 is as follows: Trichoderma longibranchii: Penicillium oxalate: Streptomyces amylase subsp. slate: Proteobacterium chrysosporum: Bacillus subtilis: Cellulosum humicum in a ratio of 1-2:1-2:1-2:1-2:1-2:1-2, with a viable count / g > 300 million; The bacterial agent composition of the bacterial solution 2 is: *C. harzianum*: *C. crocephalosporinus*: *Actinobacillus succinate* in a ratio of 1-1.5: 0.8-1: 1-1.5, with a viable count / g > 300 million. The tillage depth is 20-40cm; The particle size of the large-diameter soil aggregates is >0.25 mm.

2. The method for increasing the proportion of large-diameter soil aggregates based on straw utilization according to claim 1, characterized in that, The mass ratio of the pulverized material to organic fertilizer and water is 15-17:6-9:1-2.

3. The method for increasing the proportion of large-diameter soil aggregates based on straw utilization according to claim 1, characterized in that, The organic fertilizer is composed of cow / sheep manure, humic acid, calcium oxide, and magnesium silicate in a mass ratio of 15-17:2-3:1-1.5:0.5-1.

4. The method for increasing the proportion of large-diameter soil aggregates based on straw utilization according to claim 1, characterized in that, The bacterial solution 1 is prepared by mixing bacterial agent and water at a mass ratio of 0.8-1.2:100; the mass ratio of the mixed material to the sprayed bacterial solution 1 is 10-12:0.8-1.

2.

5. The method for increasing the proportion of large-diameter soil aggregates based on straw utilization according to claim 1, characterized in that, The bacterial solution 2 is prepared by mixing bacterial agent and water at a mass ratio of 0.8-1.2:49-51; the mass ratio of the mixed material to the sprayed bacterial solution 2 is 8-10:0.8-1.

2.

6. The method for increasing the proportion of large-diameter soil aggregates based on straw utilization according to claim 1, characterized in that, The pre-fermentation time is 2-3 days; the aerobic fermentation time is 30-50 days.

7. The method for increasing the proportion of large-diameter soil aggregates based on straw utilization according to claim 1, characterized in that, The tillage depth is 40cm; the irrigation process uses 6 tons of water per mu (unit of land area); and the anaerobic fermentation time is 70-80 days.

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