Method for measuring and calculating carbon sequestration in full life cycle of cotton planting

Abstract

The invention provides a method for measuring and calculating carbon sequestration in the whole life cycle of cotton planting. The method comprises the following steps: S1, calculating the total upstream carbon emission amount of a cotton field; s2, calculating the direct emission amount of greenhouse gas in the soil of the cotton field; s3, calculating the indirect emission amount of the greenhouse gas of the cotton field soil; s4, the carbon sink amount of the cotton field soil is calculated; s5, the carbon sink amount of the cotton byproducts is calculated; s6, the carbon sink amount of the main cotton product is calculated; and S7, based on the calculation result of the above steps, obtaining the carbon sink amount or the carbon emission amount of the cotton planting full life cycle so as to evaluate the carbon sink level of the cotton planting full life cycle. According to the invention, the system boundary of carbon emission and carbon sequestration in cotton planting is systematically and completely elaborated, so that the comprehensiveness and accuracy of measurement and calculation are ensured. According to the method, carbon emission or carbon sink of a certain link is not only concerned, the full life cycle of cotton planting is comprehensively considered, emission factors of different cotton planting areas are introduced, the measurement and calculation result is accurate and reliable, and then the carbon sink level of the full life cycle of cotton planting can be accurately evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural carbon emission measurement and calculation, and in particular to a method for measuring carbon sinks throughout the life cycle of cotton planting. Background Art

[0002] Cotton is the most important fiber crop in my country. At present, it is necessary to establish a complete carbon emission or carbon sink calculation method system for cotton planting, fully evaluate the carbon emission or carbon sink of cotton production, provide technical standards for cotton carbon sink development, and support the quality improvement, efficiency enhancement and high-quality development of the cotton industry.

[0003] Furthermore, the application number is CN117669899A, which discloses an agricultural carbon emission reduction potential analysis system, including: obtaining the base year basic data corresponding to the study area, and determining the agricultural carbon emissions, agricultural carbon sequestration and net agricultural carbon emissions corresponding to the study area in the base year based on the base year basic data; based on the preset emission reduction strategy corresponding to the study area, determining the target emission reduction scenario and the emission reduction ratio corresponding to the target emission reduction scenario from a plurality of pre-configured alternative emission reduction scenarios; based on the net agricultural carbon emissions corresponding to the base year and the emission reduction ratio, the carbon emission reduction potential analysis is performed on the study area. If not, the emission reduction ratio is adjusted to determine the emission reduction strategy optimization suggestion corresponding to the target emission reduction scenario based on the adjusted emission reduction ratio.

[0004] The applicant has found that the prior art has at least the following technical problems:

[0005] 1. Existing technologies only provide a general analytical framework for agricultural carbon emissions, which fails to fully consider the specificity of different crop production systems, especially the precise measurement of cotton. This general agricultural carbon emission analysis method is difficult to accurately measure the actual carbon emissions and carbon sink levels of cotton cultivation.

[0006] 2. There are significant differences in greenhouse gas emission factors in different regions. For example, N2O emissions from cotton fields in the middle and lower reaches of the Yangtze River are higher than those in the northwest inland cotton area and the Yellow River Basin. However, existing technologies often use a single emission factor for calculation, ignoring the differences between regions, resulting in inaccurate calculation results of carbon emissions.

[0007] 3. Existing technologies mainly focus on the direct carbon sequestration capacity of soil when assessing agricultural carbon sinks, while ignoring other important carbon sink sources in the cotton production process, such as the carbon sequestration capacity of cotton fibers and by-products such as cotton straw. The incompleteness of this assessment scope makes it impossible to fully and accurately reflect the actual carbon sequestration level of cotton cultivation.

[0008] In summary, the existing technology lacks a complete, comprehensive and accurate method to measure carbon emissions or carbon sinks throughout the entire life cycle of cotton planting.

[0009] In view of this, the present invention is proposed. Summary of the invention

[0010] Based on the above technical problems, the purpose of the present invention is to provide a method for calculating carbon sequestration during the entire life cycle of cotton planting. The preferred technical solutions among the many technical solutions provided by the present invention can produce many technical effects as described below.

[0011] To achieve the above object, the present invention provides the following technical solution: comprising the following steps:

[0012] S1: Calculate the total carbon emissions upstream of cotton fields;

[0013] S2: Calculate direct greenhouse gas emissions from cotton field soil;

[0014] S3: Calculate indirect greenhouse gas emissions from cotton field soil;

[0015] S4: Calculate the carbon sink in cotton field soil;

[0016] S5: Calculate carbon sequestration of cotton by-products;

[0017] S6: Calculate the carbon sink of cotton main products;

[0018] S7: Based on the calculation results of S1, S2, S3, S4, S5 and S6, the carbon sink or carbon emission of the whole life cycle of cotton planting is obtained to evaluate its carbon sink level.

[0019] Preferably, in S1, the total carbon emissions corresponding to greenhouse gases generated during the production, transportation and use of agricultural inputs during the entire production process from cotton sowing to harvesting are calculated, and the specific calculation formula is as follows:

[0020]

[0021] Among them, GHG snw , GHG syel and GHG syan The total upstream carbon emissions from cotton production in the Northwest Inland Cotton Region, the Yellow River Basin Cotton Region, and the Yangtze River Basin Cotton Region (kg CO2eq·hm -2 ), AM pq is the input of agricultural input q by the pth farmer (kg·hm -2 ), E.C. jnw ,EC jyel and EC jyan They are the carbon emission factors of agricultural inputs in the Northwest Inland Cotton Area, the Yellow River Basin Cotton Area and the Yangtze River Basin Cotton Area respectively.

[0022] Preferably, in S2, the direct carbon emissions of N2O caused by the input of nitrogen-containing fertilizers are calculated, and the specific calculation formula is as follows:

[0023]

[0024] Among them, GHG direnw , GHG direyel and GHG direyan The carbon emissions (kg CO2eq·hm2) of direct N2O emissions from the input of nitrogen-containing fertilizers in the Northwest Inland Cotton Region, the Yellow River Basin Cotton Region, and the Yangtze River Basin Cotton Region are -2 ), I i is the input amount of the i-th nitrogen-containing fertilizer produced in the cotton field (kg N·hm -2 ), δ inw , δ iyel and δ iyan are the N2O emission coefficients of the i-th nitrogen-containing fertilizer in the Northwest inland cotton area, the Yellow River Basin cotton area and the Yangtze River Basin cotton area, 44 / 28 is the ratio of N2O to nitrogen atoms, and 273 is the relative global warming potential (GWP) of N2O on a 100-year scale.

[0025] Preferably, in S3, the indirect emissions of greenhouse gases converted from NH3 volatilization and nitrate leaching are calculated, and the specific calculation formula is as follows:

[0026]

[0027] in, is the indirect carbon emission of N2O caused by nitrogen fertilizer input (kg CO2eq·hm -2 ), NH 3dire and They are NH3 volatilization loss and nitrate nitrogen leaching (kg·hm -2 ), Q NFI The amount of nitrogen applied to cotton fields (kgN·hm -2 ), They are the Northwest Inland Cotton Area, the Yellow River Basin Cotton Area and the Yangtze River Basin Cotton Area NH 3 Volatility coefficient, γ nw , γ yel and γ yan They are the nitrate leaching coefficients of the Northwest inland cotton area, the Yellow River basin cotton area and the Yangtze River basin cotton area respectively.

[0028] Preferably, in S4, the carbon sequestration amount of the cotton field soil is calculated based on the change in soil organic carbon reserves, and the specific calculation formula is as follows:

[0029]

[0030] Among them, dSOC and dt are the changes in soil SOC from 0 cm to 20 cm (kg C·yr -1 ) and the interval year,

[0031] γ is soil bulk density (kg·m -3 ), 20 and 10 are the conversion factors for topsoil depth and area of ​​cultivated land, respectively; 44 / 12 represents the conversion factor for C to CO2eq.

[0032] Preferably, in S5, the cotton byproduct includes cotton field straw, and the carbon sequestration amount of the cotton field straw is calculated by considering five different utilization pathways of the cotton field straw and its carbon sequestration capacity. The specific calculation formula is as follows:

[0033]

[0034] Among them, CSA straw is the carbon sequestration capacity of cotton straw (kg C·ha -1 ), B is the dry matter mass of cotton straw (kg·ha -1 ), CC straw is the carbon content of cotton straw (g kg -1 ), the carbon content of cotton straw in different cotton regions is different; P i is the ratio of the five different utilization pathways of straw, including fertilizer, feed, base material, fuel and raw material; 44 / 12 represents the conversion coefficient of C into CO2eq.

[0035] Preferably, in S6, the main cotton product includes cotton fiber, and the carbon fixation amount of the cotton fiber is calculated by the following specific calculation formula:

[0036]

[0037] Among them, CSA fiber is the carbon fixation capacity of cotton fiber (kg C·ha -1 ), Lint is cotton field lint percentage (%), C c is the carbon content of cotton fiber (g·kg -1 ), 0.95 and 44 / 12 represent the conversion coefficients.

[0038] Preferably, in S7, the carbon sink or carbon emission CSL of the whole life cycle of cotton planting is calculated by combining the above calculation results. cotton , the specific calculation formula is as follows:

[0039] The carbon sink or carbon emission of cotton throughout its life cycle is obtained to assess its carbon sink level, where a positive value indicates that it is a carbon sink throughout its life cycle, and a negative value indicates that it is a carbon source throughout its life cycle.

[0040] The preferred technical solution of the present invention can at least produce the following technical effects:

[0041] The present invention effectively solves the technical problems in the prior art that the existing agricultural carbon emission analysis framework is relatively general and uses a single emission factor for calculation, which makes it difficult to accurately reflect the carbon sink level of the entire life cycle of cotton planting, and the evaluation scope is incomplete. The present invention provides a method for calculating carbon sinks in the entire life cycle of cotton planting, including the following steps: S1: calculating the total carbon emissions from upstream cotton fields; S2: calculating the direct greenhouse gas emissions from cotton field soil; S3: calculating the indirect greenhouse gas emissions from cotton field soil; S4: calculating the carbon sink of cotton field soil; S5: calculating the carbon sink of cotton by-products; S6: calculating the carbon sink of cotton main products; S7: based on the calculation results of S1, S2, S3, S4, S5 and S6, the carbon sink or carbon emission of the entire life cycle of cotton planting is obtained to evaluate its carbon sink level. The present invention ensures the comprehensiveness and accuracy of the measurement by systematically and completely explaining the system boundaries of carbon emissions and carbon fixation in cotton planting. The present invention not only focuses on carbon emissions or carbon sinks in a certain link, but comprehensively considers the entire life cycle of cotton planting, including upstream carbon emissions, soil greenhouse gas emissions, soil carbon sinks, and carbon sinks of cotton main products and by-products, and introduces emission factors from different river basins to more accurately reflect the carbon emissions of each river basin, making the measurement results accurate and reliable, and thus being able to accurately evaluate the carbon sink level of the entire life cycle of cotton planting, providing a scientific basis for the low-carbon, green and sustainable development of the cotton industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a flow chart of a method for calculating carbon sinks during the entire life cycle of cotton planting provided by the present invention. DETAILED DESCRIPTION

[0044] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0045] According to the definition of IPCC, carbon sink refers to a system where the amount of carbon flowing into it is greater than the amount flowing out within a certain period of time, and the relevant system is a net absorption of carbon from the atmosphere. At present, the carbon sink of agricultural ecosystems is obtained by calculating the greenhouse gas emissions of agricultural production and the carbon sequestration capacity of farmland respectively. The life cycle method is mainly used to assess the greenhouse gas emission level of agricultural ecosystems, while the carbon sequestration of farmland focuses on the carbon sequestration capacity of soil and agricultural and sideline products. For example, there are many ways to use cotton and its by-products. Cotton fibers and cotton seeds have been widely used in the production of clothing and feed; cotton stalks have high cellulose and lignin content and are high-quality raw materials for bioenergy synthesis and the development of new bio-based materials. In addition, the straw produced by cotton in China is mainly used for straw return to the field, which can convert cotton stalks into soil organic carbon. However, the current agricultural carbon sink assessment is mainly focused on the planting and production systems of food crops such as wheat, rice and corn, but there is little research on the carbon sink assessment of fiber crops represented by cotton.

[0046] Carbon emissions in the cotton field production stage mainly come from two aspects: one is the upstream emissions of agricultural production materials such as fertilizers and pesticides, and the other is the direct and indirect emissions of greenhouse gases such as N2O generated by the application of nitrogen-containing fertilizers. The carbon sequestration capacity of cotton comes from the following three points: one is the carbon sequestration effect of cotton field soil; the second is cotton fiber, the main product of cotton, which is mainly used to make textiles; and the third is by-products such as cotton straw and cotton seeds, which can have a carbon sequestration effect through comprehensive utilization. From the perspective of the life cycle, the main and by-products of cotton can be regarded as large-scale carbon sinks. However, most current studies only consider the direct carbon sequestration of cotton field soil, ignore the analysis of cotton field carbon sequestration from the perspective of by-products such as cotton fiber and cotton straw, and underestimate the carbon sequestration capacity of cotton main products and by-products. At present, it is necessary to establish a complete carbon sink measurement method system for cotton field planting, fully evaluate the carbon sink of cotton production, provide technical support for the low-carbon, green and sustainable development of the cotton industry, provide technical standards for the development of cotton field carbon sinks, and support the quality improvement, efficiency enhancement and high-quality development of the cotton industry.

[0047] Based on this, the present invention provides a method for calculating carbon sequestration during the entire life cycle of cotton planting, comprising the following steps:

[0048] S1: Calculate the total carbon emissions upstream of cotton fields;

[0049] S2: Calculate direct greenhouse gas emissions from cotton field soil;

[0050] S3: Calculate indirect greenhouse gas emissions from cotton field soil;

[0051] S4: Calculate the carbon sink in cotton field soil;

[0052] S5: Calculate carbon sequestration of cotton by-products;

[0053] S6: Calculate the carbon sink of cotton main products;

[0054] S7: Based on the calculation results of S1, S2, S3, S4, S5 and S6, the carbon sink or carbon emission of the whole life cycle of cotton planting is obtained to evaluate its carbon sink level.

[0055] As an optional implementation, in S1, the total carbon emissions corresponding to greenhouse gases generated during the production, transportation, and use of agricultural inputs during the entire production process from cotton sowing to harvesting are calculated, and the specific calculation formula is as follows:

[0056]

[0057] Among them, GHG snw , GHG syel and GHG syan The total upstream carbon emissions from cotton production in the Northwest Inland Cotton Region, the Yellow River Basin Cotton Region, and the Yangtze River Basin Cotton Region (kg CO2eq·hm -2 ), AM pq is the input of agricultural input q by the pth farmer (kg·hm -2 ), E.C. jnw ,EC jyel and EC jyan They are the carbon emission factors of agricultural inputs in the Northwest Inland Cotton Area, the Yellow River Basin Cotton Area and the Yangtze River Basin Cotton Area, see Table 1 for details.

[0058] Table 1 Carbon emission factors of agricultural inputs in cotton production in China

[0059]

[0060] As an optional implementation, in S2, the direct carbon emissions of N2O caused by the input of nitrogen-containing fertilizers are calculated, and the specific calculation formula is as follows:

[0061]

[0062] Among them, GHG direnw , GHG direyel and GHG direyan The carbon emissions (kg CO2eq·hm2) of direct N2O emissions from the input of nitrogen-containing fertilizers in the Northwest Inland Cotton Region, the Yellow River Basin Cotton Region, and the Yangtze River Basin Cotton Region are -2 ), Ii is the input amount of the i-th nitrogen-containing fertilizer produced in the cotton field (kg N·hm -2 ), δ inw , δ iyel and δ iyanare the N2O emission coefficients of the i-th nitrogen-containing fertilizer in the Northwest inland cotton area, the Yellow River Basin cotton area and the Yangtze River Basin cotton area, 44 / 28 is the ratio of N2O to nitrogen atoms, and 273 is the relative global warming potential (GWP) of N2O on a 100-year scale.

[0063] As an optional implementation, in S3, the indirect emissions of NH3 volatilization and nitrate leaching converted into greenhouse gases are calculated, and the specific calculation formula is as follows:

[0064]

[0065] in, is the indirect carbon emission of N2O caused by nitrogen fertilizer input (kg CO2eq·hm -2 ), NH 3dire and They are NH3 volatilization loss and nitrate nitrogen leaching (kg·hm -2 ), Q NFI The amount of nitrogen applied to cotton fields (kgN·hm -2 ), They are the Northwest Inland Cotton Area, the Yellow River Basin Cotton Area and the Yangtze River Basin Cotton Area NH 3 Volatility coefficient, γ nw , γ yel and γ yan They are the nitrate leaching coefficients of the Northwest inland cotton area, the Yellow River basin cotton area and the Yangtze River basin cotton area respectively.

[0066] As an optional implementation, in S4, based on the change in soil organic carbon reserves, the carbon sequestration amount of the cotton field soil is calculated, and the specific calculation formula is as follows:

[0067]

[0068] Among them, dSOC and dt are the changes in soil SOC from 0 cm to 20 cm (kg C·yr -1 ) and the interval year,

[0069] γ is soil bulk density (kg·m -3 ), 20 and 10 are the conversion factors for topsoil depth and area of ​​cultivated land, respectively; 44 / 12 represents the conversion factor for C to CO2eq.

[0070] As an optional implementation, in S5, the cotton byproduct includes cotton field straw, and the carbon sequestration amount of the cotton field straw is calculated by considering five different utilization pathways of the cotton field straw and its carbon sequestration capacity. The specific calculation formula is as follows:

[0071]

[0072] Among them, CSAstraw is the carbon sequestration capacity of cotton straw (kg C·ha -1 ), B is the dry matter mass of cotton straw (kg·ha -1 ), CC straw is the carbon content of cotton straw (g kg -1 ), the carbon content of cotton straw in different cotton regions is different, see Table 2 for details; P i is the ratio of the five different utilization pathways of straw, including fertilizer, feed, base material, fuel and raw material; 44 / 12 represents the conversion coefficient of C into CO2eq.

[0073] Table 2 Carbon content of cotton straw in different regions of China

[0074]

[0075] As an optional implementation, in S6, the main cotton product includes cotton fiber, and the carbon fixation amount of the cotton fiber is calculated by the following specific calculation formula:

[0076]

[0077] Among them, CSA fiber is the carbon fixation capacity of cotton fiber (kg C·ha -1 ), Lint is cotton field lint percentage (%), C c is the carbon content of cotton fiber (g·kg -1 ), 0.95 and 44 / 12 represent the conversion coefficients.

[0078] As an optional implementation, in S7, the carbon sink or carbon emission CSL of the whole life cycle of cotton planting is calculated by combining the above calculation results. cotton , the specific calculation formula is as follows:

[0079] The carbon sink or carbon emission of cotton throughout its life cycle is obtained to assess its carbon sink level, where a positive value indicates that it is a carbon sink throughout its life cycle, and a negative value indicates that it is a carbon source throughout its life cycle.

[0080] The present invention ensures the comprehensiveness and accuracy of the calculation by systematically and completely expounding the system boundaries of carbon emissions and carbon sequestration in cotton planting. The present invention not only focuses on carbon emissions or carbon sinks in a certain link, but comprehensively considers the entire life cycle of cotton planting, including upstream carbon emissions, soil greenhouse gas emissions, soil carbon sinks, and carbon sinks of cotton main products and by-products, and introduces emission factors of different river basins to more accurately reflect the carbon emissions of each river basin, so that the calculation results are accurate and reliable, and then the carbon sink level of the entire life cycle of cotton planting can be accurately evaluated, providing a scientific basis for the low-carbon, green and sustainable development of the cotton industry.

[0081] The present invention takes into account the carbon sequestration of cotton main products (such as cotton fiber) and by-products (such as cotton field straw) during the growth and processing process, making the assessment of the carbon sink level of cotton cultivation over the entire life cycle more comprehensive and accurate.

[0082] The present invention corrects different greenhouse gas emission factors corresponding to different regions, so that the calculation of carbon emissions is more in line with the actual situation and the accuracy of carbon emissions calculation is improved.

[0083] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0084] In the description of the present invention, it should be noted that, unless otherwise specified, the meaning of "plurality" is two or more; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0085] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "an example" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0087] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for calculating carbon sinks during the entire life cycle of cotton planting, characterized in that: The steps include: S1: Calculate the total carbon emissions upstream of cotton fields; S2: Calculate direct greenhouse gas emissions from cotton field soil; S3: Calculate indirect greenhouse gas emissions from cotton field soil; S4: Calculate the carbon sink in cotton field soil; S5: Calculate carbon sequestration of cotton by-products; S6: Calculate the carbon sink of cotton main products; S7: Based on the calculation results of S1, S2, S3, S4, S5 and S6, the carbon sink or carbon emission of the whole life cycle of cotton planting is obtained to evaluate its carbon sink level.

2. The method for calculating carbon sinks during the entire life cycle of cotton planting according to claim 1, characterized in that: In S1, the total carbon emissions corresponding to greenhouse gases generated during the production, transportation, and use of agricultural inputs during the entire production process from cotton sowing to harvesting are calculated. The specific calculation formula is as follows: Among them, GHG snw , GHG syel and GHG syan The total upstream carbon emissions from cotton production in the Northwest Inland Cotton Region, the Yellow River Basin Cotton Region, and the Yangtze River Basin Cotton Region (kg CO2eq·hm -2 ), AM pq is the input of agricultural input q by the pth farmer (kg·hm -2 ), E.C. jnw ,EC jyel and EC jyan They are the carbon emission factors of agricultural inputs in the Northwest Inland Cotton Area, the Yellow River Basin Cotton Area and the Yangtze River Basin Cotton Area respectively.

3. The method for calculating carbon sinks during the entire life cycle of cotton planting according to claim 2, characterized in that: In S2, the direct carbon emissions of N2O caused by the input of nitrogen-containing fertilizers are calculated. The specific calculation formula is as follows: Among them, GHG direnw , GHG direyel and GHG direyan The carbon emissions (kg CO2eq·hm2) of direct N2O emissions from the input of nitrogen-containing fertilizers in the Northwest Inland Cotton Region, the Yellow River Basin Cotton Region, and the Yangtze River Basin Cotton Region are -2 ), Ii is the input amount of the i-th nitrogen-containing fertilizer produced in the cotton field (kg N·hm -2 ), δ inw , δ iyel and δ iyan are the N2O emission coefficients of the i-th nitrogen-containing fertilizer in the Northwest inland cotton area, the Yellow River Basin cotton area and the Yangtze River Basin cotton area, 44 / 28 is the ratio of N2O to nitrogen atoms, and 273 is the relative global warming potential (GWP) of N2O on a 100-year scale.

4. The method for calculating carbon sinks during the entire life cycle of cotton planting according to claim 3, characterized in that: In S3, the indirect emissions of NH3 volatilization and nitrate leaching converted into greenhouse gases are calculated. The specific calculation formula is as follows: in, is the indirect carbon emission of N2O caused by nitrogen fertilizer input (kg CO2eq·hm -2 ), NH 3dire and They are NH3 volatilization loss and nitrate nitrogen leaching amount (kg·hm -2 ), Q NF I is the amount of nitrogen applied to cotton fields (kg N·hm -2 ), and They are the Northwest Inland Cotton Area, the Yellow River Basin Cotton Area and the Yangtze River Basin Cotton Area NH 3 Volatility coefficient, γ nw , γ yel and γ yan They are the nitrate leaching coefficients of the Northwest inland cotton area, the Yellow River basin cotton area and the Yangtze River basin cotton area respectively.

5. The method for calculating carbon sinks during the entire life cycle of cotton planting according to claim 4, characterized in that: In S4, based on the change in soil organic carbon reserves, the carbon sequestration amount of the cotton field soil is calculated, and the specific calculation formula is as follows: in, is the carbon sequestration capacity of cotton field soil (kg C·yr -1 ), dSOC and dt are the changes in soil SOC from 0 cm to 20 cm (kg C·yr -1 ) and the interval year, γ is the soil bulk density (kg·m -3 ), 20 and 10 are the conversion factors for topsoil depth and area of ​​cultivated land, respectively; 44 / 12 represents the conversion factor for C to CO2eq.

6. The method for calculating carbon sinks during the entire life cycle of cotton planting according to claim 5, characterized in that: In S5, the cotton byproduct includes cotton field straw. Considering five different utilization pathways of the cotton field straw and its carbon sequestration capacity, the carbon sequestration amount of the cotton field straw is calculated. The specific calculation formula is as follows: Among them, CSA straw is the carbon sequestration capacity of cotton straw (kg C·ha -1 ), B is the dry matter mass of cotton straw (kg·ha -1 ), CC straw is the carbon content of cotton straw (g kg -1 ), the carbon content of cotton straw in different cotton regions is different; P i is the ratio of the five different utilization pathways of straw, including fertilizer, feed, base material, fuel and raw material; 44 / 12 represents the conversion coefficient of C into CO2eq.

7. A method for calculating carbon sinks during the entire life cycle of cotton planting according to claim 6, characterized in that: In S6, the main cotton product includes cotton fiber, and the carbon fixation amount of the cotton fiber is calculated using the following specific calculation formula: Among them, CSA fiber is the carbon fixation capacity of cotton fiber (kg C·ha -1 ), Lint is cotton field lint percentage (%), C c is the carbon content of cotton fiber (g·kg -1 ), 0.95 and 44 / 12 represent the conversion coefficients.

8. The method for calculating carbon sinks during the entire life cycle of cotton planting according to claim 7, characterized in that: In S7, the carbon sink or carbon emission CSL of the whole life cycle of cotton planting is calculated by combining the above calculation results. cotton , the specific calculation formula is as follows: The carbon sink or carbon emission of cotton throughout its life cycle is obtained to assess its carbon sink level, where a positive value indicates that it is a carbon sink throughout its life cycle, and a negative value indicates that it is a carbon source throughout its life cycle.

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