A method for increasing the content of active organic carbon in paddy soil

Abstract

The application belongs to the technical field of soil improvement, and particularly relates to a method for increasing the content of active organic carbon in paddy field soil. By adding crop straw, inorganic fertilizer and a mixture composed of algal species and bacterial species in an artificial carrier, the effect of reasonably optimizing the components of the artificial carrier is achieved, and then necessary nutrients are provided for the cultivation of periphyton; when the artificial carrier is appropriately put into the paddy field with the depth of 2-3 cm of the field surface water, the rapid growth of periphyton in the flooded environment is facilitated, and the photosynthetic carbon fixation and extracellular material secretion capacity of periphyton are simultaneously improved, and then the effect of increasing the active organic carbon in the paddy field soil is achieved.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to a method for increasing the active organic carbon content of paddy field soil. Background Technology

[0002] Soil active organic carbon is a type of soil organic carbon. Although it accounts for a small proportion of soil organic carbon, it can respond rapidly to the soil carbon pool and influence soil microbial activity and nitrogen and phosphorus form transformation. Therefore, increasing the content of soil active organic carbon is more conducive to improving soil effective fertility.

[0003] However, existing technologies typically use methods such as applying bio-organic fertilizers, returning green manure to the field, or returning straw to the field to increase soil active organic carbon. However, these methods are often time-consuming, and straw residues can also have adverse effects on crop root growth.

[0004] Panicles are microbial aggregates that form in flooded environments, mainly composed of algae, bacteria, and their extracellular polymers. They are abundant in species and have a large biomass in paddy fields. During their growth, panicles secrete various bioactive substances, and the biomass left on the soil surface after apoptosis also helps release different forms of organic matter and nutrients. However, current research does not include studies on increasing the content of active organic carbon in soil through the cultivation of panicles. Summary of the Invention

[0005] The purpose of this invention is to provide a method for increasing the active organic carbon content of paddy field soil. By introducing artificial carriers into the paddy field, it is beneficial to promote the rapid growth of periphytes, thereby increasing the active organic carbon content of the soil.

[0006] This invention provides a method for increasing the active organic carbon content of paddy field soil, comprising the following steps: placing an artificial carrier into the paddy field and maintaining the water depth at the surface of the paddy field at 2-3 cm; placing the artificial carrier into the paddy field again 20-30 days after placement; the artificial carrier comprises the following raw materials in parts by weight: 80-90 parts of crop straw, 10-20 parts of inorganic fertilizer, and 1-1.5 parts of a mixture composed of algae and bacteria; the initial placement of the artificial carrier is 150-200 kg / ha; the subsequent placement of the artificial carrier is 10-30 kg / ha.

[0007] Preferably, the artificial carrier is first introduced 3-5 days after the rice seedlings are transplanted.

[0008] Preferably, the algal species include Chlorella, Nostoc, and filamentous algae;

[0009] The bacterial species include Bacillus and Pseudomonas;

[0010] The mass ratio of algae to bacteria is (3-4):1.

[0011] Preferably, the mass ratio of Chlorella, Nostoc, and Fibrophyte is 1:(1-1.5):1;

[0012] The mass ratio of Bacillus to Pseudomonas is (1-1.5):1.

[0013] Preferably, the effective viable counts of Bacillus and Pseudomonas are ≥10. 7 CFU / g.

[0014] Preferably, the crop straw includes rice straw and / or wheat straw.

[0015] Preferably, the inorganic fertilizer comprises the following components in parts by weight: 40-50 parts urea, 25-35 parts diammonium phosphate, and 10-15 parts calcium magnesium phosphate.

[0016] Preferably, the particle size of the artificial carrier is ≤2cm.

[0017] Beneficial effects:

[0018] This invention provides a method for increasing the active organic carbon content of paddy field soil, comprising the following steps: placing an artificial carrier into the paddy field and maintaining the water depth at the surface of the paddy field at 2-3 cm; placing the artificial carrier into the paddy field again 20-30 days after placement; the artificial carrier comprises the following raw materials in parts by weight: 80-90 parts of crop straw, 10-20 parts of inorganic fertilizer, and 1-1.5 parts of a mixture composed of algae and bacteria; the initial placement of the artificial carrier is 150-200 kg / ha; the subsequent placement of the artificial carrier is 10-30 kg / ha. By adding crop straw, inorganic fertilizer, and a mixture of algae and microorganisms to the artificial carrier, the composition of the artificial carrier is optimized, thus providing the necessary nutrients for cultivating periphytes. Appropriate application of the artificial carrier while maintaining a paddy field water depth of 2-3 cm promotes the rapid growth of periphytes in flooded environments. Further application of the artificial carrier to the paddy field simultaneously enhances the photosynthetic carbon fixation capacity of periphytes, laying the foundation for increasing the active organic carbon in the soil. Experiments show that compared to paddy field soil treated with only granular carriers containing wheat straw and inorganic fertilizer, the application of the artificial carrier using the method provided by this invention significantly increases the TOC content, microbial biomass carbon content, and dissolved organic carbon content of the surface soil. Therefore, the method provided by this invention is beneficial for cultivating periphytes in paddy fields, thereby increasing the active organic carbon content of paddy field soil. Detailed Implementation

[0019] This invention provides a method for increasing the active organic carbon content of paddy field soil, comprising the following steps: placing an artificial carrier into the paddy field and maintaining the water depth at the surface of the paddy field at 2-3 cm; placing the artificial carrier into the paddy field again 20-30 days after placement; the artificial carrier comprises the following raw materials in parts by weight: 80-90 parts of crop straw, 10-20 parts of inorganic fertilizer, and 1-1.5 parts of a mixture composed of algae and bacteria; the initial placement of the artificial carrier is 150-200 kg / ha; the subsequent placement of the artificial carrier is 10-30 kg / ha.

[0020] In this invention, unless otherwise specified, rice is managed with water and fertilizer according to local planting practices. All raw materials and culture media used in this invention are conventionally purchased unless otherwise specified.

[0021] The artificial carrier of the present invention preferably comprises 80-90 parts by weight, more preferably 85 parts; the crop straw preferably includes one or more of rice straw or wheat straw. The particle size of the crop straw of the present invention is preferably ≤50 mesh.

[0022] Based on the mass fraction of crop straw, the artificial carrier of this invention preferably includes 10-20 parts of inorganic fertilizer, more preferably 15 parts. The inorganic fertilizer of this invention preferably includes the following components in parts by mass: 40-50 parts urea, 25-35 parts diammonium phosphate, and 10-15 parts calcium magnesium phosphate. The mass fraction of urea in this invention is further preferably 45-50 parts, more preferably 50 parts; the mass fraction of diammonium phosphate is further preferably 30-35 parts, more preferably 35 parts; and the mass fraction of calcium magnesium phosphate is further preferably 12-15 parts, more preferably 15 parts. The preparation method of the inorganic fertilizer of this invention preferably includes: mixing urea, diammonium phosphate, and calcium magnesium phosphate to obtain the inorganic fertilizer. This invention does not have special requirements for the mixing method; uniform mixing is preferred. The urea, diammonium phosphate, and calcium magnesium phosphate can be purchased conventionally. Organic fertilizer prepared by adding urea, diammonium phosphate and calcium magnesium phosphate can provide nitrogen and phosphorus nutrients for periwinkle and accelerate its growth.

[0023] Based on the mass fraction of crop straw, the artificial carrier of the present invention preferably comprises 1 to 1.5 parts of a mixture composed of algae and fungi, more preferably 1 part or 1.5 parts. The dry mass ratio of algae to fungi in the mixture of algae and fungi of the present invention is preferably (3 to 4):1, more preferably 3:1 or 4:1. In the present invention, the algae preferably include Chlorella, Nostoc, and filamentous algae, and more preferably include dried Chlorella, Nostoc, and filamentous algae; the mass ratio of the dried Chlorella, Nostoc, and filamentous algae is preferably 1:(1 to 1.5):1, more preferably 1:1:1 or 1:1.5:1.

[0024] The preferred method for preparing the algal strains of the present invention includes: inoculating Chlorella, Nostoc, and Filamenta into WC liquid culture medium for culture to obtain Chlorella culture medium, Nostoc culture medium, and Filamenta culture medium, respectively.

[0025] The culture media of Chlorella, Nostoc, and Filamenta were centrifuged and concentrated in sequence to obtain Chlorella concentrate, Nostoc concentrate, and Filamenta concentrate, respectively.

[0026] The Chlorella concentrate, Nostoc commune concentrate, and filamentous algae concentrate were respectively mixed with a protective agent and freeze-dried to obtain dried Chlorella, Nostoc commune, and filamentous algae, respectively.

[0027] The dried Chlorella, Nostoc, and Fibrocystidia are mixed to obtain the algal species.

[0028] In this invention, the inoculum size of *Chlorella vulgaris* is preferably 2.8% to 3.5% of the volume of the WC liquid culture medium, more preferably 3%. The preferred conditions for culturing *Chlorella vulgaris* in this invention include: a temperature preferably 23–26°C, more preferably 25°C; a culturing time preferably 7–10 days, more preferably 9 days; a light intensity preferably 2000–3000 lux, more preferably 2500 lux; and a light duration preferably 10–14 h / d, more preferably 12 h / d. The centrifugation speed in this invention is preferably 6000–8000 r / min, more preferably 7000 r / min, and the centrifugation time is 8–12 min, more preferably 10 min. The protective agent mixed with the *Chlorella vulgaris* concentrate is preferably trehalose, and the amount of trehalose added is preferably 0.9% to 1.2% of the concentrate's mass, more preferably 1%. This invention does not have special requirements for the components of the WC liquid culture medium or the freeze-drying process; techniques well known in the art can be used.

[0029] In this invention, the inoculum size of *Nostoc commune* is preferably 2.8% to 3.5% of the volume of the WC liquid culture medium, more preferably 3%. The preferred conditions for culturing *Nostoc commune* in this invention include: a temperature preferably of 23–26°C, more preferably 25°C; a culturing time preferably of 7–10 days, more preferably 9 days; a light intensity preferably of 2000–3000 lux, more preferably 2500 lux; and a light duration preferably of 10–14 h / d, more preferably 12 h / d. The centrifugation speed is preferably 6000–8000 r / min, more preferably 7000 r / min, and the centrifugation time is 8–12 min, more preferably 10 min. The protective agent mixed with the *Nostoc commune* concentrate is preferably trehalose, and the amount of trehalose added is preferably 0.9% to 1.2% of the concentrate's mass, more preferably 1%. This invention does not have special requirements for the components of the WC liquid culture medium or the freeze-drying process; techniques well known in the art can be used.

[0030] In this invention, the inoculum amount of the filamentous algae is preferably 2.8% to 3.5% of the volume of the WC liquid culture medium, more preferably 3%. The preferred conditions for filamentous algae cultivation in this invention include: a temperature preferably 23 to 26°C, more preferably 25°C; a cultivation time preferably 7 to 10 days, more preferably 9 days; a light intensity preferably 2000 to 3000 lux, more preferably 2500 lux; and a light duration preferably 10 to 14 h / d, more preferably 12 h / d. The preferred centrifugation speed in this invention is 7000 to 9000 r / min, more preferably 8000 r / min, and the centrifugation time is 8 to 12 min, more preferably 10 min. The preferred protective agent mixed with the filamentous algae concentrate is trehalose, and the amount of trehalose added is preferably 0.9% to 1.2% of the concentrate's mass, more preferably 1%. This invention does not have special requirements for the components of the WC liquid culture medium or the freeze-drying process; techniques well known in the art can be used.

[0031] The bacterial strains described in this invention preferably include Bacillus and Pseudomonas, more preferably including dried Bacillus and Pseudomonas; the mass ratio of the dried Bacillus to Pseudomonas is preferably (1-1.5):1, more preferably 1:1 or 1.5:1; the effective viable count of the dried Bacillus is preferably ≥10. 7 CFU / g; the effective viable count of the dried Pseudomonas aeruginosa is preferably ≥10. 7 CFU / g.

[0032] In this invention, the preferred method for preparing the bacterial strain includes: inoculating Bacillus and Pseudomonas into LB liquid medium and culturing them in a shaker to obtain Bacillus culture medium and Pseudomonas culture medium, respectively;

[0033] The Bacillus culture medium and the Pseudomonas culture medium were centrifuged and concentrated in sequence to obtain Bacillus concentrate and Pseudomonas concentrate, respectively.

[0034] The Bacillus concentrate and Pseudomonas concentrate were mixed with glycerol and freeze-dried to obtain dried Bacillus and Pseudomonas, respectively.

[0035] The dried Bacillus and Pseudomonas were mixed to obtain the bacterial strain.

[0036] The inoculation amount of Bacillus in this invention is preferably 0.04% to 0.06% of the volume of the LB liquid culture medium, more preferably 0.05%. In this invention, the preferred culture conditions for the Bacillus include: a shaking speed of 160 to 200 r / min, more preferably 180 r / min; a temperature of 28 to 32°C, more preferably 30°C; and a culture time of 18 to 24 h, more preferably 24 h. The preferred centrifugation speed is 6500 to 8000 r / min, more preferably 7500 r / min, and the centrifugation time is 8 to 12 min, more preferably 10 min. The preferred amount of glycerol added is 0.8% to 1.2% of the concentrated Bacillus mass, more preferably 1%. This invention does not have special requirements for the components of the LB liquid culture medium or the freeze-drying process; techniques well known in the art can be used.

[0037] The inoculation amount of *Pseudomonas* in this invention is preferably 0.04% to 0.06% of the volume of the LB liquid culture medium, more preferably 0.05%. In this invention, the preferred culture conditions for *Pseudomonas* include: a shaking speed preferably of 160 to 200 r / min, more preferably 180 r / min; a temperature preferably of 28 to 32°C, more preferably 30°C; and a culture time preferably of 18 to 24 h, more preferably 24 h. The preferred centrifugation speed is 6500 to 8000 r / min, more preferably 7500 r / min, and the centrifugation time is 8 to 12 min, more preferably 10 min. The preferred amount of glycerol added is 0.8% to 1.2% of the concentrated *Pseudomonas* mass, more preferably 1%. This invention does not have special requirements for the components of the LB liquid culture medium or the freeze-drying process; techniques well known in the art can be used.

[0038] In this invention, the artificial carrier is preferably in granular form, and the particle size of the artificial carrier is preferably ≤2cm. Preparing an artificial granular carrier facilitates the retention of nutrients from straw powder and inorganic fertilizer within the carrier, continuously providing nutrients to the pericarp.

[0039] In this invention, the method for preparing the artificial carrier preferably includes: mixing the crop straw, inorganic fertilizer, and a mixture composed of algae and bacteria to obtain a mixture; and sequentially extruding, granulating, drying, and cooling the mixture to obtain the artificial carrier.

[0040] In this invention, the crop straw is preferably crushed, ground, and sieved to obtain crop straw powder. In this invention, the mesh size of the crop straw during sieving is preferably 45-60 mesh, more preferably 50 mesh. Processing the crop straw facilitates the subsequent preparation of artificial carriers. This invention does not have special requirements for the crushing and grinding methods; techniques well-known in the art can be used.

[0041] After obtaining the crop straw powder, the present invention preferably mixes the crop straw powder, inorganic fertilizer, and a mixture composed of algae and microorganisms to obtain a mixture. The preparation methods of the inorganic fertilizer and the mixture composed of algae and microorganisms have been specifically defined and described in the above technical solutions and will not be repeated here. The mixing in the present invention is preferably uniform; the mixing method is not particularly limited, as long as uniform mixing is ensured.

[0042] After obtaining the mixture, the present invention preferably subjectes the mixture to extrusion granulation, drying, and cooling sequentially to obtain the artificial carrier. The drying temperature is preferably ≤30℃. The present invention does not have special requirements for the extrusion granulation and cooling processes; techniques well-known in the art can be used. Granulation facilitates better nutrient release from the artificial carrier, increasing the biomass of rice paddy periphytes.

[0043] After obtaining the artificial carrier, the present invention releases the artificial carrier into the paddy field. In this invention, the initial release rate of the artificial carrier is preferably 150–200 kg / ha, more preferably 160–190 kg / ha, and even more preferably 180 kg / ha. The present invention does not have special requirements for the release method of the artificial carrier; techniques well known in the art can be used. By rationally optimizing the release rate of the artificial carrier, it is beneficial to meet the needs of rapid growth of periphytes and improve their activity.

[0044] When the artificial carrier is first introduced, the water depth in the paddy field is preferably 2-3 cm, more preferably 2 cm. The artificial carrier is preferably introduced 3-5 days after rice seedling transplanting, more preferably 4 days later. Optimizing the water depth and timing of the artificial carrier introduction promotes the growth of periphytes.

[0045] After the initial application of the artificial carrier for 20-30 days, the present invention preferably applies the artificial carrier again. In this invention, the second application of the artificial carrier is preferably 20-25 days after the initial application, more preferably 20 days or 25 days. The second application rate of the artificial carrier is preferably 10-30 kg / ha, more preferably 10 kg / ha or 20 kg / ha. When the artificial carrier is applied again, the surface water depth of the paddy field is preferably maintained at 2-3 cm, more preferably 2 cm. The second application of the artificial carrier ensures the continuous growth of clumps of organisms within the paddy field.

[0046] The present invention, by introducing artificial carriers into paddy fields using the aforementioned method, promotes the rapid growth of periphytes in flooded environments and simultaneously enhances their photosynthetic carbon fixation capacity, laying the foundation for increasing active organic carbon in the soil. Experiments show that, compared to paddy field soil without artificial carriers, the application of artificial carriers using the technical solution provided by this invention significantly increases the TOC content, microbial biomass carbon content, and dissolved organic carbon content of the paddy field surface soil.

[0047] To further illustrate the present invention, the following detailed description of a method for increasing the active organic carbon content in paddy field soil, in conjunction with embodiments, is provided by the present invention, but should not be construed as limiting the scope of protection of the present invention.

[0048] In a specific embodiment of the present invention, the paddy field is located in Jurong City, Jiangsu Province, and the experimental plots selected in each embodiment and comparative example are all from the same paddy field.

[0049] Unless otherwise specified, irrigation and drainage times and frequencies during the rice growing season shall be determined according to the rice growth needs and in accordance with local management practices.

[0050] Example 1

[0051] A method for increasing the active organic carbon content of paddy field soil comprises the following steps:

[0052] (1) Select paddy fields and divide them into experimental plots of 5m×5m. Apply basal fertilizer, specifically: 150kgN / ha of nitrogen fertilizer and 60kgP / ha of phosphorus fertilizer. Use a rotary tiller to till the rice planting area to a depth of 10cm, then irrigate and keep the water depth at 3cm;

[0053] (2) Transplant rice seedlings to the rice planting area and keep the water depth in the field at 2cm;

[0054] (3) After the rice seedlings have turned green again 4 days after transplanting, artificial granular carriers are added to the water in the field at a rate of 200 kg / ha;

[0055] The artificial granular carrier consists of wheat straw, inorganic fertilizer, and a mixture of algae and bacteria.

[0056] The preparation method of artificial particulate carriers is as follows:

[0057] After drying the wheat straw, crush and grind it into a fine powder, then pass it through a 50-mesh sieve for later use.

[0058] Weigh out urea, diammonium phosphate and calcium magnesium phosphate fertilizer in a mass ratio of 50:35:10 to form an inorganic fertilizer for later use.

[0059] Chlorella was inoculated into WC liquid medium at a volume ratio of 3% and cultured in a greenhouse. The culture conditions were: 25℃, 12h light per day, and cultured for 9 days to obtain Chlorella culture medium. The obtained Chlorella culture medium was centrifuged and concentrated. The centrifugation conditions were 7000r / min for 10min. The precipitate obtained after centrifugation was Chlorella sludge. Trehalose was added at 1% of the mass of Chlorella sludge as a protective agent, and then freeze-dried to obtain dried Chlorella for later use.

[0060] Nostoc flagelliforme was inoculated into WC liquid medium at a volume ratio of 3% and cultured in a greenhouse. The culture conditions were: 25℃, 12h light per day, and 9 days of culture to obtain the Nostoc flagelliforme culture solution. The obtained Nostoc flagelliforme culture solution was centrifuged and concentrated. The centrifugation conditions were 7000r / min for 10min. The precipitate obtained after centrifugation was Nostoc flagelliforme algal sludge. Trehalose was added at 1% of the mass of the Nostoc flagelliforme algal sludge as a protective agent, and then freeze-dried to obtain dried Nostoc flagelliforme for later use.

[0061] Filamentosa was inoculated into WC liquid medium at a volume ratio of 3% and cultured in a greenhouse. The culture conditions were: 25℃, 12h light per day, and 9 days of culture to obtain filamentosa culture solution. The obtained filamentosa culture solution was centrifuged and concentrated. The centrifugation conditions were 8000r / min for 10min. The precipitate obtained after centrifugation was filamentosa sludge. Trehalose was added at 1% of the mass of the filamentosa sludge as a protective agent, and then freeze-dried to obtain dried filamentosa for later use.

[0062] The dried Chlorella, Nostoc, and Fibrocystidia were mixed in a mass ratio of 1:1:1 to obtain the algal strain for preparing the artificial carrier; Chlorella, Nostoc, and Fibrocystidia were all purchased from the Freshwater Algal Culture Collection of the Chinese Academy of Sciences.

[0063] Bacillus was inoculated into LB liquid medium at a volume ratio of 0.5% and cultured on a shaker at 30℃ and 180 rpm for 24 hours. The Bacillus culture was then centrifuged and concentrated at 7500 rpm for 10 minutes. The precipitate obtained after centrifugation was the Bacillus concentrate. Glycerol was added as a preservative at 1% of the concentrate's mass, followed by freeze-drying to obtain dried Bacillus. The effective viable count of the dried Bacillus was ≥10⁻⁶. 7 CFU / g, for later use;

[0064] Pseudomonas aeruginosa was inoculated into LB liquid medium at a volume ratio of 0.5% and cultured on a shaker at 30°C and 180 rpm for 24 hours. The culture was then centrifuged and concentrated at 7500 rpm for 10 minutes. The precipitate obtained after centrifugation was the Pseudomonas aeruginosa concentrate. Glycerol was added at 1% of the concentrate's mass as a preservative, followed by freeze-drying to obtain dried Pseudomonas aeruginosa. The effective viable count of the dried Pseudomonas aeruginosa was ≥10⁻⁶. 7 CFU / g, for later use;

[0065] The dried Bacillus and Pseudomonas were mixed at a mass ratio of 1:1 to obtain the strain for preparing the artificial vector; both Bacillus and Pseudomonas were purchased from the China General Microbiological Culture Collection Center.

[0066] The algal and bacterial strains used to prepare the artificial carrier were mixed at a mass ratio of 3:1 to obtain a mixture of algal and bacterial strains.

[0067] Weigh out 90 parts of wheat straw powder, 15 parts of inorganic fertilizer, and 1 part of a mixture of algae and bacteria. Mix them evenly, then perform conventional extrusion granulation, dry at 30℃, and cool to obtain an artificial carrier with a particle size of less than 2 cm.

[0068] (4) After 25 days of adding artificial particle carriers according to step (3), 10 kg / ha of artificial particle carriers were added again to ensure that the periphytes grow vigorously and secrete bioactive substances such as extracellular polymers and extracellular enzymes during the growth process.

[0069] (5) On the 30th and 60th day after the first addition of artificial particle carrier, topsoil samples of 0-20cm were collected in each experimental plot using the five-point soil sampling method as a treatment. Each treatment was repeated three times. The contents of TOC, microbial biomass carbon, and dissolved organic carbon in the soil samples were determined according to the "Soil Agricultural Chemical Analysis Method". The results were recorded as implementation 1-1, implementation 1-2 and implementation 1-3 respectively (the results are shown in Table 1).

[0070] Comparative Example 1

[0071] 90 parts of wheat straw powder and 15 parts of inorganic fertilizer from Example 1 were weighed and mixed. After being mixed evenly, the mixture was subjected to conventional extrusion granulation, dried at 30°C, and cooled to obtain artificial particle carriers with a particle size of less than 2 cm.

[0072] Comparative Example 1 was prepared by adding an artificial granular carrier containing only wheat straw and inorganic fertilizer, with the remaining steps being the same as in Example 1. Specifically, on days 30 and 60 after adding the artificial granular carrier containing only wheat straw and inorganic fertilizer, topsoil samples (0–20 cm) were collected from each experimental plot using the five-point sampling method, with three replicates. The TOC, microbial biomass carbon, and dissolved organic carbon contents of the soil samples were determined according to the "Soil Agricultural Chemical Analysis Methods," and the results were recorded as Comparative Example 1-1, Comparative Example 1-2, and Comparative Example 1-3, respectively (results are shown in Table 1).

[0073] Results and Analysis:

[0074] Table 1. Results of soil active organic carbon tests in Example 1 and Comparative Example 1

[0075]

[0076] As shown in Table 1, the results of the determination of microbial biomass carbon and dissolved organic carbon content in paddy field soils showed that, after 60 days of the first artificial carrier introduction, the average TOC content of the topsoil in Example 1 was 19.5 g / kg, while that in Comparative Example 1 was only 17.5 g / kg; the average microbial biomass carbon content of the topsoil in Example 1 was 73.7 mg / kg, while that in Comparative Example 1 was only 59.4 mg / kg; and the average dissolved organic carbon content of the topsoil in Example 1 was 481 mg / kg, while that in Comparative Example 1 was only 427 mg / kg.

[0077] Example 2

[0078] A method for increasing the active organic carbon content of paddy field soil comprises the following steps:

[0079] (1) Select paddy fields and divide them into experimental plots of 5m×5m. Apply basal fertilizer, with the following specific amounts: 140kgN / ha of nitrogen fertilizer and 55kgP / ha of phosphorus fertilizer. Use a rotary tiller to till the rice planting area to a depth of 10cm, and then irrigate to maintain a water depth of 3cm;

[0080] (2) Transplant rice seedlings to the rice planting area and keep the water depth in the field at 2cm;

[0081] (3) Four days after transplanting, artificial granular carriers are added to the water in the field at a rate of 180 kg / ha;

[0082] The artificial granular carrier consists of wheat straw, inorganic fertilizer, and a mixture of algae and bacteria.

[0083] The method for preparing the artificial carrier is as follows:

[0084] After drying the wheat straw, crush and grind it into a fine powder, then pass it through a 50-mesh sieve for later use.

[0085] Weigh out urea, diammonium phosphate and calcium magnesium phosphate fertilizer in a mass ratio of 50:35:10 to form an inorganic fertilizer for later use.

[0086] The dried Chlorella, Nostoc, and Filamenta were prepared in the same way as in Example 1, except that the dried Chlorella, Nostoc, and Filamenta were mixed in a mass ratio of 1:1.5:1 to obtain the algal strain for preparing the artificial carrier.

[0087] The preparation method of dried Bacillus and Pseudomonas is the same as that in Example 1, except that: dried Bacillus and Pseudomonas are mixed at a mass ratio of 1.5:1 to obtain the strain for preparing the artificial carrier;

[0088] The algal and bacterial strains used to prepare the artificial carrier were mixed at a mass ratio of 4:1 to obtain a mixture of algal and bacterial strains.

[0089] Weigh out 80 parts of wheat straw powder, 15 parts of inorganic fertilizer, and 1 part of a mixture of algae and bacteria. Mix them evenly, then perform conventional extrusion granulation, dry at 30℃, and cool to obtain an artificial carrier with a particle size of less than 2 cm.

[0090] (4) After the first artificial carrier is added for 20 days, artificial particle carrier is added again at a rate of 20 kg / ha to ensure that the pericarp grows vigorously and secretes bioactive substances such as extracellular polymers and extracellular enzymes during the growth process.

[0091] (5) On the 30th and 60th day after the first addition of artificial carrier, topsoil samples of 0-20cm were collected in each experimental plot using the five-point soil sampling method as a treatment. Each treatment was repeated three times. The content of TOC, microbial biomass carbon, dissolved organic carbon and other parameters of the soil samples were determined according to the "Soil Agricultural Chemical Analysis Methods". The results were recorded as implementation 2-1, implementation 2-2 and implementation 2-3 (the results are shown in Table 1).

[0092] Comparative Example 2

[0093] Weigh 80 parts of wheat straw powder and 15 parts of inorganic fertilizer from Example 2 and mix them. After mixing evenly, perform conventional extrusion granulation, dry at 30°C, and cool to obtain an artificial particle carrier with a particle size of less than 2 cm.

[0094] Comparative Example 2 was prepared by adding an artificial granular carrier containing only wheat straw and inorganic fertilizer, with the remaining steps being the same as in Example 2. The test results were recorded as comparative examples 2-1, 2-2, and 2-3 (results are shown in Table 1).

[0095] Results and Analysis

[0096] Table 2. Results of soil active organic carbon tests in Example 2 and Comparative Example 2

[0097]

[0098] As shown in Table 2, the results of the determination of microbial biomass carbon and dissolved organic carbon content in paddy field soils indicate that, 60 days after the initial application of the artificial carrier, the average TOC content in the topsoil of paddy field in Example 2 was 18.7 g / kg, while that in Comparative Example 2 was only 17.3 g / kg; the average microbial biomass carbon content in the topsoil of paddy field in Example 2 was 71.8 mg / kg, while that in Comparative Example 2 was only 60.4 mg / kg; and the average dissolved organic carbon content in the topsoil of paddy field in Example 2 was 467 mg / kg, while that in Comparative Example 2 was only 429 mg / kg.

[0099] In summary, compared with paddy soils that only use artificial granular carriers containing wheat straw and inorganic fertilizers, the application of artificial carriers using the technical solution provided by this invention significantly increases the TOC content, microbial biomass carbon content, and dissolved organic carbon content of the paddy surface soil.

[0100] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for increasing the content of active organic carbon in paddy soil, characterized by, The method comprises the following steps: The artificial carrier is put into the rice field, and the water depth of the rice field is kept at 2-3 cm; After 20-30 days, the artificial carrier is put into the rice field again, and the water depth of the rice field is kept at 2-3 cm; The artificial carrier comprises the following raw materials in mass fraction: 80-90 parts of crop straw, 10-20 parts of inorganic fertilizer and 1-1.5 parts of a mixture of algal species and bacterial species; The inorganic fertilizer comprises the following components in mass fraction: 40-50 parts of urea, 25-35 parts of diammonium phosphate and 10-15 parts of calcium magnesium phosphate; The algal species comprises Chlorella, Nostoc and filamentous algae; the bacterial species comprises Bacillus and Pseudomonas; the mass ratio of the algal species to the bacterial species is (3-4):1; The mass ratio of Chlorella, Nostoc and filamentous algae is 1:(1-1.5):1; the mass ratio of Bacillus and Pseudomonas is (1-1.5):1; The effective viable cell number of the bacillus and pseudomonas is ≥10 7 CFU / g; The amount of the artificial carrier put for the first time is 150-200 kg / ha; The amount of the artificial carrier put for the second time is 10-30 kg / ha.

2. The method of claim 1, wherein, The artificial carrier is put for the first time 3-5 days after rice seedlings are transplanted.

3. The method of claim 1, wherein, The crop straw comprises rice straw and / or wheat straw.

4. The method according to any one of claims 1 to 3, characterized in that, The particle size of the artificial carrier is ≤2 cm.

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