A method for constructing a technical model of soil organic carbon improvement by multi-source organic material

Abstract

This invention discloses a method for constructing a technical model for enhancing soil organic carbon using multiple organic materials. First, indoor simulation experiments are conducted to study the net carbon compensation effect of adding exogenous organic materials to the soil under specific regional climatic conditions, establishing a quantitative relationship between this effect and the amount of organic materials applied. Then, based on field trials conducted within the region, the optimal application ratio of different types of organic materials for increasing soil carbon and fertility while improving crop yield is determined. Finally, based on the target increase in soil organic carbon, a technical model is constructed to quantify the application amount of different types of organic materials. This invention is completely different from the traditional concept of soil organic fertilization. It can accurately assess the amount of different types of organic materials applied based on the target increase in soil organic carbon within a specific region and the type of exogenous organic material, achieving a quantitative increase in soil organic carbon. This method plays an important role in the transformation of low- and medium-yield farmland, the improvement of arable land quality, and the construction of high-standard farmland.

Description

Technical Field

[0001] This invention relates to a method for constructing a technology model for improving soil organic carbon using multi-source organic materials, belonging to the field of soil management and farmland fertility improvement technology. Background Technology

[0002] With the intensification of global climate change and the increasing severity of soil degradation, enhancing soil organic carbon sequestration has become a key approach to achieving sustainable agricultural development and carbon neutrality goals. Soil organic carbon is not only a core indicator of soil fertility but also directly affects crop yield, soil water holding capacity, and microbial diversity. However, long-term intensive agriculture has led to a significant decline in the global soil organic carbon pool. While the application of traditional single organic materials (such as straw or manure) can partially alleviate this problem, it suffers from limitations such as low carbon conversion efficiency and poor stability. Therefore, how to scientifically integrate multiple sources of organic materials (such as bio-organic fertilizers, biochar, and peat-based amendments) and optimize their synergistic effects to enhance soil carbon sequestration potential has become an important research direction in the fields of soil management and farmland fertility improvement.

[0003] The combined application of multiple organic materials offers a new approach to enhancing soil organic carbon, but the construction of its technical model still faces significant challenges. The significant differences in carbon-to-nitrogen ratios, degradation rates, and microbial utilization efficiencies among different organic materials make it difficult to predict their carbon sequestration effects in soil. Existing research mostly focuses on single materials or simple ratios, lacking a systematic model to quantify the relationship between multi-source material inputs and the dynamic response of the soil carbon pool. Furthermore, factors such as regional bioclimate, soil type, and farming practices further increase the difficulty of achieving universal applicability of the technology. To address this gap, there is an urgent need to construct a soil organic carbon enhancement technology model based on multiple organic materials to integrate organic material characteristics, environmental variables, and soil biological processes to predict carbon sequestration effects under different scenarios. This model needs to combine experimental data with mathematical simulations to optimize material ratios and application strategies, thereby providing customized soil carbon management solutions for different agricultural ecosystems. This invention aims to establish a method for constructing a multi-source organic material technology model to enhance soil organic carbon, providing a scientific basis and practical tools for enhancing soil carbon sequestration, promoting sustainable agricultural development, and achieving "dual carbon" goals. It has important strategic and practical significance for improving arable land fertility, ensuring food security, and addressing climate change. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for constructing a technology model for increasing soil organic carbon from multiple sources of organic materials.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for constructing a technology model for enhancing soil organic carbon from multiple sources of organic materials, characterized by the following steps:

[0007] 1) Soil samples were collected from the area to be improved. Indoor simulation experiments were conducted, and different types of exogenous organic materials were added to the soil. The net carbon compensation effect of the added organic materials on the soil under the climatic conditions of the study area was analyzed, and a quantitative relationship between the net carbon compensation of different types of organic materials and their application rate was established, as detailed below:

[0008] Let X be the application rate of exogenous organic material (kg C ha). -1 Y represents the net carbon compensation effect (g / kg) of the corresponding organic material. -1 If X = f(X), then Y = f(X).

[0009] 2) Conduct field trials in the areas to be improved to study the effects of different types of organic materials on soil fertility and crop yield. By comprehensively considering the effects of soil carbon enrichment and crop yield increase, determine the optimal ratio of carbon content for different types of organic materials in the study area, as follows:

[0010] Suppose there are n types of organic materials, and K is the optimal ratio of carbon application to them, then K = X1:X2:…:X n ;

[0011] 3) Based on the target increase in soil organic carbon, a technical model for increasing soil organic carbon using multi-source organic materials was constructed, and the application rates of different types of organic materials were quantitatively calculated, as follows:

[0012] Let ΔC be the target increase in soil organic carbon (g kg). -1 ),but And each organic material satisfies the optimal ratio determined in step 2).

[0013] Preferably, in step 1), the soil used for the indoor simulation test comes from the area to be improved. After being air-dried, it is passed through a 2mm sieve, and crop residues are picked out. The soil is compacted to adjust the bulk density to the average value of the area to be improved. The indoor simulation test lasts for 1 year. The test temperature, soil moisture content, and cultivation days at the corresponding stages are set according to the average temperature of the crop growing season and the soil fallow season in the study area, soil redox conditions, and duration. At the same time, a control test without adding organic materials is carried out.

[0014] Preferably, if the soil in the area to be improved is dryland soil, in step 1), after the soil and organic materials are mixed evenly, nitrogen, phosphorus and potassium mineral fertilizers are added according to the conventional fertilization amount for the area to be improved, wherein the nitrogen fertilizer is ammonium nitrate, and the phosphorus and potassium fertilizers are dipotassium hydrogen phosphate. The soil moisture content is adjusted to 60% field water holding capacity, and water is replenished once a week by weighing to maintain constant soil moisture. For paddy soil, after the soil and organic materials are mixed evenly, nitrogen, phosphorus and potassium mineral fertilizers are added according to the conventional fertilization amount for the study area, wherein the nitrogen fertilizer is ammonium nitrate, and the phosphorus and potassium fertilizers are dipotassium hydrogen phosphate. Water is added to 1 cm above the soil surface, and water is replenished once a week to maintain the soil flooding layer height.

[0015] Preferably, after the indoor simulation test in step 1), the soil organic carbon content of different test treatments is sampled and analyzed, and the increase in organic carbon in the experimental group with added organic materials compared with the control group without added organic materials is calculated, which is the net carbon compensation effect of different types of organic materials on the soil.

[0016] Preferably, exogenous organic materials include bio-organic fertilizers, humic acid conditioners, biochar or peat products.

[0017] Preferably, in step 2), the field experiment involves continuous application of exogenous organic materials for two years or more, with at least two types of exogenous organic materials used, and two or more proportions of different types of organic materials applied together. At the same time, the exogenous organic materials are evenly applied to the soil surface before tilling, and then tilled according to local customs to mix them with the topsoil.

[0018] In the field trials, apart from the addition of exogenous organic materials, other field management practices, including crop types, cropping systems, and fertilization amounts, were kept consistent with local practices.

[0019] Preferably, in step 2), when determining the optimal ratio of carbon application for different types of organic materials in the area to be improved, organic materials from different sources are applied in a series of ratios for field trials. Based on the results of the field trials, the experimental treatment with the highest yield, the highest carbon increase, and the highest nutrient fertility is selected by comparing the organic carbon increase, nitrogen, phosphorus, and potassium nutrients, as well as the yield of different treatments. This determines the optimal application ratio of different organic materials. In cases where the response patterns of soil carbon enrichment and crop yield increase are inconsistent, crop yield increase is used as the primary evaluation indicator, followed by organic carbon and nitrogen, phosphorus, and potassium nutrient fertility.

[0020] Preferably, for plots that actually require improvement, the bulk density of the background soil is measured. Simultaneously, based on the soil bulk density set during indoor simulation experiments, the ratio of the two is calculated to correct the model's predicted value for increasing soil organic carbon using multi-source organic materials, as detailed below:

[0021] Let the background soil bulk density be BD1, and the soil bulk density set for the incubation experiment be BD2, then

[0022] Preferably, step 4) is also included: after the model is built, exogenous organic materials are applied to the area to be improved according to the model.

[0023] Completely different from the traditional concept of soil organic fertilization, this invention can accurately assess the amount of different types of organic materials to be applied based on the target increase in soil organic carbon in a specific area and the type of exogenous organic materials, thereby achieving a quantitative increase in soil organic carbon. It plays an important role in the transformation of low- and medium-yield fields, the improvement of arable land quality, and the construction of high-standard farmland.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. The method of this invention can quantify the relationship between the input of exogenous organic materials and the dynamic response of the soil carbon pool in a specific area. This invention proposes a method for constructing a multi-source organic material enhancement technology model for soil organic carbon. The experimental temperature, soil moisture content, and cultivation days at the corresponding stages are set according to the average temperature, soil redox conditions, and duration of the crop growing season and soil fallow season in the study area. Through a one-year experiment, the increase in soil organic carbon is analyzed, the net carbon compensation effect of different types of organic materials on the soil is determined, and a quantitative relationship between the organic material application rate and the net carbon compensation effect of different types of organic materials is established.

[0026] 2. The method of this invention can optimize the optimal ratio of carbon application for different types of organic materials in the study area. The method proposed in this invention is to construct a multi-source organic material technology model to enhance soil organic carbon. It involves the combination and application of two or more organic materials. Through field trials, soil organic carbon, nitrogen, phosphorus and potassium nutrient fertility and crop yield are continuously monitored to determine the optimal carbon application ratio for different types of organic materials to enhance soil carbon enrichment and crop yield in the study area.

[0027] 3. The method of this invention can quantitatively increase the content of soil organic carbon in a specific research area by utilizing multiple sources of organic materials. The method proposed in this invention for constructing a technology model for increasing soil organic carbon using multiple sources of organic materials can accurately calculate the application amount of different types of organic materials under the given target increase amount of soil organic carbon. The model prediction accuracy reaches more than 85%, and can provide customized soil carbon management solutions for different agricultural ecosystems. Attached Figure Description

[0028] Figure 1 This is a quantitative relationship between the net carbon compensation of different types of organic materials and their application amount in Example 1.

[0029] Figure 2This is a comparison of the effects of soil carbon enrichment and fertilization and crop yield increase in different experimental treatments in Example 1.

[0030] Figure 3 This is a comparison between the model fitting values ​​and the measured values ​​from the field experiment for soil organic carbon enhancement in Example 1.

[0031] Figure 4 This is a quantitative relationship between the net carbon compensation of different types of organic materials and their application amount in Example 2.

[0032] Figure 5 This is a comparison of the effects of soil carbon enrichment and fertilization and crop yield increase in different experimental treatments in Example 2.

[0033] Figure 6 This is a comparison between the model fitting values ​​and the measured values ​​from the field experiment for soil organic carbon enhancement in Example 2.

[0034] Figure 7 This is a quantitative relationship between the net carbon compensation of different types of organic materials and their application amount in Example 3.

[0035] Figure 8 This is a comparison of the effects of soil carbon enrichment and fertilization and crop yield increase in different experimental treatments in Example 3.

[0036] Figure 9 This is a comparison between the model fitting values ​​and the measured values ​​from the field experiment for soil organic carbon enhancement in Example 3.

[0037] The present invention will be further described below with reference to specific embodiments. Detailed Implementation

[0038] The following examples further illustrate the content of the present invention, but should not be construed as limiting the invention. Modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are all within the scope of the invention. Specific instruments or reagents used in the embodiments of the present invention are provided below. However, it should be understood that these are merely exemplary and not intended to limit the invention. Materials of the same or similar type, model, quality, properties, or functions as the reagents and instruments described below can be used to implement the present invention. Unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art. Specific determination methods not specified in the experiments all adopt the determination methods described in *Soil Agricultural Chemical Analysis Methods*, edited by Lu Rukun et al., China Agricultural Science and Technology Press, 1999.

[0039] Due to limitations in experimental conditions, only experiments involving two types of exogenous carbon application have been conducted so far. However, based on the model principles, applying two or more types of exogenous carbon is also feasible.

[0040] Example 1

[0041] This experiment was conducted on soil samples from Changtu County, Tieling City, Liaoning Province. A technical model for increasing soil organic carbon was constructed using bio-organic fertilizer and biochar. The initial organic carbon content of the soil to be improved was 11.85 g / kg. -1 The bulk density is 1.35 g / cm³. -3 The bio-organic fertilizer contains 285.2 g of carbon per kg. -1 The biochar contains 190.4 g of carbon per kg. -1 The main cropping system in the study area is a single-crop maize system, with the maize growing season lasting from May to October each year, lasting about 6 months, and an average temperature of 20℃. The soil fallow season lasts from November to April of the following year, lasting about 6 months, and an average temperature of -1℃.

[0042] The specific implementation steps are as follows:

[0043] Step 1: Collect topsoil samples from the study area, air-dry them, pass them through a 2mm sieve to remove crop residues, and then mix them thoroughly with bio-organic fertilizer or biochar. Simultaneously, add nitrogen, phosphorus, and potassium mineral fertilizers and conduct indoor simulation experiments. The organic material application gradients set for this cultivation experiment were 0.0016, 0.0024, 0.0032, 0.0040, 0.0048, and 0.0056 g C g. -1 Soil equivalent to field application rates of 4, 6, 8, 10, 12, and 14 t C ha -1 The soil bulk density was set to 1.30 g / cm³, the average value for the study area, by compacting the soil. -3 The added nitrogen, phosphorus, and potassium nutrient mineral fertilizers were 0.26 g / kg ammonium nitrate. -1 Soil, dipotassium hydrogen phosphate 0.08 g / kg -1 Soil equivalent to 240 kg N ha of field fertilizer -1 90kg P2O5 ha -1 120kg K2Oha -1 The entire experiment was first cultured at -1℃ for 6 months, then at 20℃ for 6 months, with a control treatment without organic materials. Each treatment was replicated three times, and the soil volume was 110g / replication (dry basis). Before the experiment, the soil was pre-cultured at 20℃ for one week. After the experiment began, water was added weekly using a weighing method to maintain 60% field capacity. After the experiment, soil organic carbon content was sampled and analyzed, and the increase in soil organic carbon in the organic material-added experimental group compared to the control group without organic materials was calculated. This represents the net carbon compensation effect of bio-organic fertilizer and biochar on the soil. Based on this, a quantitative relationship was established between the net carbon compensation of different types of organic materials and their application rate, such as... Figure 1 As shown.

[0044] Step 2: Select farmland within the study area that has been continuously planted with maize for more than 30 years (representative of ordinary farmland within the study area) and set up field plots with added bio-organic fertilizer and biochar. The total amount of exogenous carbon applied annually is set at 2000 kg C ha. -1 The carbon ratios of bio-organic fertilizer and biochar were set as follows: 1) control treatment without added exogenous carbon; 2) carbon ratio of 0:10; 3) carbon ratio of 1:9; 4) carbon ratio of 2:8; 5) carbon ratio of 3:7; 6) carbon ratio of 4:6; 7) carbon ratio of 5:5. The experiment was conducted for two consecutive years, with soil tillage systems, fertilization rates, and other field management practices remaining consistent with local conditions. Each year after crop maturity, topsoil samples were collected from each plot to analyze total organic matter, dissolved organic carbon, total nitrogen, phosphorus, and potassium content, and available organic matter content. Simultaneously, maize yield was measured in each plot on a single harvest basis. In this embodiment, the range standardization method was used to standardize the contents of total nitrogen, available nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium in the soil. The average of the standardized variables was then used to reflect the comprehensive nutrient fertility of the soil. By comparing the average crop yield, soil organic carbon, and nitrogen, phosphorus, and potassium nutrient fertility over multiple years, the experimental treatment with the optimal effect of soil carbon enrichment and crop yield increase was screened. This led to the determination of the optimal ratio of carbon application for different types of organic materials in the study area. When the response patterns of soil carbon enrichment and crop yield increase were inconsistent, crop yield increase was used as the primary evaluation indicator, followed by organic carbon and nitrogen, phosphorus, and potassium nutrients. Figure 2 As shown.

[0045] Step 3: Based on Steps 1 and 2, and according to the quantitative relationship between the net carbon compensation of bio-organic fertilizer and biochar and their respective application rates, as well as their optimal combination ratio in the improved area, a technical model for increasing soil organic carbon in the study area using these two organic materials is constructed, as follows:

[0046] Let X be the application rate of bio-organic fertilizer (kg C ha). -1 Y represents the application rate of biochar (kg C ha). -1 ), where ΔC is the target increase in soil organic carbon (g kg). -1 ), BD is the bulk density of the improved soil (g / cm³). -3 ),but:

[0047]

[0048] Step 4: Evaluate the model established in Step 3, assuming that the soil organic carbon content in the study area needs to be increased by 0.085% units, i.e., ΔC is 0.85 g kg. -1 The initial bulk density of the improved soil was 1.35 g / cm³. -3Substituting these values ​​into the above model, the calculated application rates of bio-organic fertilizer (X) and biochar (Y) are 409 and 1634 kg C ha, respectively. -1 Based on the model-calculated application rates of two organic materials, a field validation experiment was further conducted. An experimental group with added materials and a control group without added materials were set up, with maize as the crop. One year later, the organic carbon content of the topsoil was measured, and the model-fitted values ​​for soil organic carbon enhancement were compared and analyzed with the measured values ​​from the field experiment. Figure 3 As shown.

[0049] The experimental results showed that the net carbon compensation of the soil in the study area by bio-organic fertilizer and biochar showed a significant linear positive correlation with their respective application rates. The combination of the two organic materials with a carbon ratio of 2:8 had the best effect on comprehensive soil fertility improvement and corn yield increase. After calculating the amount of the two organic materials by applying the model, the experimental measured value of soil organic carbon increase differed from the model fitting value by 7.30%, with an error of less than 15.0%, which is within the acceptable error range. Therefore, the model has high accuracy.

[0050] Example 2

[0051] This experiment was conducted on soil samples from Hailun City, Suihua City, Heilongjiang Province. A technical model for increasing soil organic carbon was constructed using bio-organic fertilizer and biochar. The initial organic carbon content of the soil to be improved was 32.12 g / kg. -1 The bulk density is 1.06 g / cm³. -3 The bio-organic fertilizer contains 285.2 g of carbon per kg. -1 The biochar contains 190.4 g of carbon per kg. -1 The main cropping system in the study area is a single-crop maize system, with the maize growing season lasting about 6 months from May to October each year, and an average temperature of 16℃. The soil fallow season lasts about 6 months from November to April of the following year, with an average temperature of -10℃.

[0052] The specific implementation steps are as follows:

[0053] Step 1: Collect topsoil samples from the study area, air-dry them, pass them through a 2mm sieve to remove crop residues, and then mix them thoroughly with bio-organic fertilizer or biochar. Simultaneously, add nitrogen, phosphorus, and potassium mineral fertilizers and conduct indoor simulation experiments. The organic material application gradients set for this cultivation experiment were 0.0016, 0.0024, 0.0032, 0.0040, 0.0048, and 0.0056 g C g. -1 Soil equivalent to field application rates of 4, 6, 8, 10, 12, and 14 t C ha -1 The soil bulk density was set to 1.30 g / cm³, the average value for the study area, by compacting the soil. -3The added nitrogen, phosphorus, and potassium nutrient mineral fertilizers were 0.26 g / kg ammonium nitrate. -1 Soil, dipotassium hydrogen phosphate 0.08 g / kg -1 Soil equivalent to 240 kg N ha of field fertilizer -1 90kg P2O5 ha -1 120kg K2Oha -1 The entire experiment was first cultured at -10℃ for 6 months, then at 16℃ for 6 months, with a control treatment without organic materials. Each treatment was replicated three times, and the soil volume was 110g / replication (dry basis). Before the experiment, the soil was pre-cultured at 16℃ for one week. After the experiment began, water was added weekly using a weighing method to maintain 60% field capacity. After the experiment, soil organic carbon content was sampled and analyzed, and the increase in soil organic carbon in the organic material-added experimental group compared to the control group without organic materials was calculated. This represents the net carbon compensation effect of bio-organic fertilizer and biochar on the soil. Based on this, a quantitative relationship was established between the net carbon compensation of different types of organic materials and their application rate, such as... Figure 4 As shown.

[0054] Step 2: Select farmland within the study area that has been continuously planted with maize for more than 30 years (representative of ordinary farmland within the study area) and set up field plots with added bio-organic fertilizer and biochar. The total amount of exogenous carbon applied annually is set at 2000 kg C ha. -1 The carbon ratios of bio-organic fertilizer and biochar were set as follows: 1) control treatment without added exogenous carbon; 2) carbon ratio of 0:10; 3) carbon ratio of 1:9; 4) carbon ratio of 3:7. The experiment was conducted continuously for three years, with soil tillage systems, fertilization rates, and other field management practices remaining consistent with local conditions. Each year after crop maturity, topsoil samples were collected from each plot to analyze total organic matter, easily oxidizable organic carbon, total nitrogen, phosphorus, and potassium content, and available organic matter content. Simultaneously, maize yield was measured in each plot. This example uses range standardization to standardize the contents of total nitrogen, available nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium in the soil. The average of the standardized variables is then used to reflect the comprehensive nutrient fertility of the soil. By comparing the multi-year average crop yield, soil organic carbon, and nitrogen, phosphorus, and potassium nutrient fertility, the experimental treatment with the optimal effect of increasing soil carbon and fertility on crop yield was selected, thereby determining the optimal carbon ratio for different types of organic materials in the study area. Figure 5 As shown.

[0055] Step 3: Based on Steps 1 and 2, and according to the quantitative relationship between the net carbon compensation of bio-organic fertilizer and biochar and their respective application rates, as well as their optimal combination ratio in the improved area, a technical model for increasing soil organic carbon in the study area using these two organic materials is constructed, as follows:

[0056] Let X be the application rate of bio-organic fertilizer (kg C ha). -1 Y represents the application rate of biochar (kg C ha). -1 ), where ΔC is the target increase in soil organic carbon (g kg). -1 ), BD is the bulk density of the improved soil (g / cm³). -3 ),but:

[0057]

[0058] Step 4: Evaluate the model established in Step 3, assuming that the soil organic carbon content in the study area needs to be increased by 0.150% units, i.e., ΔC is 1.50 g kg. -1 The initial bulk density of the improved soil was 1.06 g / cm³. -3 Substituting these values ​​into the above model, the calculated application rates of bio-organic fertilizer (X) and biochar (Y) are 495 and 4451 kg C ha, respectively. -1 Based on the model-calculated application rates of two organic materials, a field validation experiment was further conducted. An experimental group with added materials and a control group without added materials were set up, with maize as the crop. One year later, the organic carbon content of the topsoil was measured, and the model-fitted values ​​for soil organic carbon enhancement were compared and analyzed with the measured values ​​from the field experiment. Figure 6 As shown.

[0059] The experimental results showed that the net carbon compensation of the soil in the study area by bio-organic fertilizer and biochar showed a significant linear positive correlation with their respective application rates. The best effect of applying the two organic materials in a carbon ratio of 1:9 was to improve soil fertility and increase maize yield. After calculating the amount of the two organic materials by applying the model, the difference between the experimentally measured value and the model fitting value of soil organic carbon increase was 13.12%, with an error of less than 15.0%, which is within the acceptable error range. Therefore, the model has high accuracy.

[0060] Example 3

[0061] This experiment was conducted on soil samples from Hailun City, Suihua City, Heilongjiang Province. A technical model for increasing soil organic carbon was constructed using bio-organic fertilizer and peat products. The initial organic carbon content of the soil to be improved was 31.07 g / kg. -1 The bulk density is 1.12 g / cm³. -3 The bio-organic fertilizer contains 285.2 g of carbon per kg. -1 The peat product contains 413.5 g of carbon per kg. -1The main cropping system in the study area is a single-crop maize system, with the maize growing season lasting about 6 months from May to October each year, and an average temperature of 16℃. The soil fallow season lasts about 6 months from November to April of the following year, with an average temperature of -10℃.

[0062] The specific implementation steps are as follows:

[0063] Step 1: Collect topsoil samples from the study area, air-dry them, pass them through a 2mm sieve to remove crop residues, and then mix them thoroughly with bio-organic fertilizer or peat products. Simultaneously, add nitrogen, phosphorus, and potassium mineral fertilizers and conduct indoor simulation experiments. The organic material application gradients set for this cultivation experiment were 0.0016, 0.0024, 0.0032, 0.0040, 0.0048, and 0.0056 g C g. -1 Soil equivalent to field application rates of 4, 6, 8, 10, 12, and 14 t C ha -1 The soil bulk density was set to 1.30 g / cm³, the average value for the study area, by compacting the soil. -3 The added nitrogen, phosphorus, and potassium nutrient mineral fertilizers were 0.26 g / kg ammonium nitrate. -1 Soil, dipotassium hydrogen phosphate 0.08 g / kg -1 Soil equivalent to 240 kg N ha of field fertilizer -1 90kg P2O5 ha -1 120kg K2Oha -1 The entire experiment was first cultured at -10℃ for 6 months, then at 16℃ for 6 months, with a control treatment without organic materials. Each treatment was replicated three times, and the soil volume was 110g / replication (dry basis). Before the experiment, the soil was pre-cultured at 16℃ for one week. After the experiment began, water was added weekly using a weighing method to maintain 60% field capacity. After the experiment, soil organic carbon content was sampled and analyzed, and the increase in soil organic carbon in the organic material-added experimental group compared to the control group without organic materials was calculated. This represents the net carbon compensation effect of bio-organic fertilizer and peat products on the soil. Based on this, a quantitative relationship was established between the net carbon compensation of different types of organic materials and their application rate, such as... Figure 7 As shown.

[0064] Step 2: Select farmland within the study area that has been continuously planted with maize for more than 30 years (representative of ordinary farmland within the study area) and set up field plot trials with added bio-organic fertilizer and peat products. The total annual exogenous carbon application is set at 2000 kg C ha. -1The carbon application ratios of bio-organic fertilizer and peat products were set as follows: 1) a control treatment without added exogenous carbon; 2) a carbon ratio of 0:10; 3) a carbon ratio of 1:9; and 4) a carbon ratio of 3:7. The experiment was conducted continuously for three years, with soil tillage systems, fertilization rates, and other field management practices remaining consistent with local conditions. Each year after crop maturity, topsoil samples were collected from each plot to analyze total organic matter, easily oxidizable organic carbon, total nitrogen, phosphorus, and potassium content, and available organic matter content. Simultaneously, maize yields were measured in individual plots. This embodiment used the range standardization method to standardize the contents of total nitrogen, available nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium in the soil. The average of the standardized variables was then used to reflect the comprehensive nutrient fertility of the soil. By comparing the multi-year average crop yield, soil organic carbon, and nitrogen, phosphorus, and potassium nutrient fertility, the experimental treatment with the optimal effect of increasing soil carbon and fertility on crop yield was selected, thereby determining the optimal carbon application ratio for different types of organic materials in the study area, such as... Figure 8 As shown.

[0065] Step 3: Based on Steps 1 and 2, and according to the quantitative relationship between the net carbon compensation of bio-organic fertilizer and peat products and their respective application rates, as well as their optimal combination ratio in the improved area, a technical model for increasing soil organic carbon in the study area using these two organic materials is constructed, as follows:

[0066] Let X be the application rate of bio-organic fertilizer (kg C ha). -1 Y represents the application rate of peat product (kg C ha). -1 ), where ΔC is the target increase in soil organic carbon (g kg). -1 ), BD is the bulk density of the improved soil (g / cm³). -3 ),but:

[0067]

[0068] Step 4: Evaluate the model established in Step 3, assuming that the soil organic carbon content in the study area needs to be increased by 0.215%, i.e., ΔC is 2.15 g kg. -1 The initial bulk density of the improved soil was 1.12 g / cm³. -3 Substituting these values ​​into the above model, the calculated application rates of bio-organic fertilizer (X) and peat product (Y) are 500 and 4500 kg C ha, respectively. -1 Based on the model-calculated application rates of two organic materials, a field validation experiment was further conducted. An experimental group with added materials and a control group without added materials were set up, with maize as the crop. One year later, the organic carbon content of the topsoil was measured, and the model-fitted values ​​for soil organic carbon enhancement were compared and analyzed with the measured values ​​from the field experiment. Figure 9 As shown.

[0069] The experimental results show that the net carbon compensation of the soil in the study area by bio-organic fertilizer and peat products is significantly linearly positively correlated with their respective application rates. The best effect of applying the two organic materials in a carbon ratio of 1:9 is to comprehensively improve soil fertility and increase maize yield. After calculating the amount of the two organic materials by applying the model, the experimental measured value of soil organic carbon increase differs from the model fitting value by 7.07%, with an error of less than 15.0%, which is within the acceptable error range. Therefore, the model has high accuracy.

Claims

1. A method for constructing a technical model for enhancing soil organic carbon from multiple sources of organic materials, characterized in that... The steps include: 1) Soil samples were collected from the area to be improved. Indoor simulation experiments were conducted, and different types of exogenous organic materials were added to the soil. The net carbon compensation effect of the added organic materials on the soil under the climatic conditions of the study area was analyzed, and a quantitative relationship between the net carbon compensation of different types of organic materials and their application rate was established, as detailed below: set up X This refers to the application rate of exogenous organic materials, expressed in kg C ha. -1 , Y The net carbon offset effect of the corresponding organic materials is expressed in g / kg. -1 , ; 2) Conduct field trials in the areas to be improved to study the effects of different types of organic materials on soil fertility and crop yield. By comprehensively considering the effects of soil carbon enrichment and crop yield increase, determine the optimal ratio of carbon content for different types of organic materials in the study area, as follows: Suppose there are n types of organic materials. K The optimal ratio of carbon applied to them is... ; 3) Based on the target increase in soil organic carbon, a technical model for increasing soil organic carbon using multi-source organic materials was constructed, and the application rates of different types of organic materials were quantitatively calculated, as follows: set up The target increase in soil organic carbon (g / kg) -1 ,but And each organic material satisfies the optimal ratio determined in step 2). Specifically, for plots that actually require improvement, the bulk density of the background soil is measured. Simultaneously, based on the soil bulk density set during the indoor simulation experiment, the ratio of the two is calculated to correct the model's predicted value for increasing soil organic carbon using multi-source organic materials. The calculation formula is as follows: Let the bulk density of the background soil be... BD1 The soil bulk density was set at [value] during the cultivation experiment. BD2 ,but .

2. The method for constructing a multi-source organic material enhancement technology model for soil organic carbon according to claim 1, characterized in that: Step 1) The soil used for the indoor simulation test came from the area to be improved. After air drying, it was passed through a 2mm sieve and crop residues were removed. The soil was compacted to adjust the bulk density to the average value of the area to be improved. The indoor simulation test lasted for 1 year. The test temperature, soil moisture content and the number of cultivation days at the corresponding stages were set according to the average temperature of the crop growing season and the soil fallow season in the study area, soil redox conditions and duration. At the same time, a control test without organic materials was carried out.

3. The method for constructing a multi-source organic material enhancement technology model for soil organic carbon according to claim 1 or 2, characterized in that: If the soil in the area to be improved is dryland soil, in step 1), after the soil and organic materials are mixed evenly, nitrogen, phosphorus and potassium mineral fertilizers are added according to the conventional fertilization amount for the area to be improved. The nitrogen fertilizer is ammonium nitrate, and the phosphorus and potassium fertilizers are dipotassium hydrogen phosphate. The soil moisture content is adjusted to 60% field water holding capacity, and water is added once a week by weighing to maintain constant soil moisture. For paddy soil, after the soil and organic materials are mixed evenly, nitrogen, phosphorus and potassium mineral fertilizers are added according to the conventional fertilization amount for the study area. The nitrogen fertilizer is ammonium nitrate, and the phosphorus and potassium fertilizers are dipotassium hydrogen phosphate. Water is added to 1 cm above the soil surface, and water is added once a week to maintain the height of the soil flooding layer.

4. The method for constructing a multi-source organic material enhancement technology model for soil organic carbon according to claim 1 or 2, characterized in that: After the indoor simulation experiment in step 1) is completed, the soil organic carbon content of different experimental treatments is sampled and analyzed, and the increase in organic carbon in the experimental group with added organic materials compared with the control group without added organic materials is calculated, which is the net carbon compensation effect of different types of organic materials on soil.

5. The method for constructing a multi-source organic material enhancement technology model for soil organic carbon according to claim 1 or 2, characterized in that: Exogenous organic materials include bio-organic fertilizers, biochar, or peat products.

6. The method for constructing a multi-source organic material enhancement technology model for soil organic carbon according to claim 1 or 2, characterized in that: In step 2), the field experiment involves the continuous application of exogenous organic materials for two years or more, with at least two types of exogenous organic materials used. Different types of organic materials are applied in two or more proportions. At the same time, the exogenous organic materials are evenly applied to the soil surface before tilling, and then tilled and mixed with the topsoil.

7. The method for constructing a multi-source organic material enhancement technology model for soil organic carbon according to claim 6, characterized in that: In step 2), when determining the optimal ratio of carbon application for different types of organic materials in the area to be improved, organic materials from different sources are applied in a series of proportions for field trials. Based on the results of the field trials, the experimental treatment with the highest yield, the highest carbon increase, and the highest nutrient fertility is selected by comparing the organic carbon increase, nitrogen, phosphorus, and potassium nutrient content, and yield of different treatments. This determines the optimal application ratio of different organic materials. When the response patterns of soil carbon enrichment and crop yield increase are inconsistent, crop yield increase is used as the primary evaluation indicator, followed by organic carbon and nitrogen, phosphorus, and potassium nutrient fertility.

8. The method for constructing a technology model for enhancing soil organic carbon from multiple sources of organic materials according to claim 1 or 2, characterized in that: It also includes step 4): After the model is built, exogenous organic materials are applied to the area to be improved according to the model.

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