Method for evaluating soil and water conservation carbon sink volume of slope conversion to terrace measures

Abstract

The present invention discloses a method for evaluating the soil and water conservation carbon sink amount of slope conversion to terrace measures, which is specifically implemented according to the following steps: First, clarify the baseline scenario and project scenario of slope conversion to terrace measures; then measure the bulk density and organic carbon content of the surface soil in the baseline scenario and project scenario at the beginning of the implementation of slope conversion to terrace measures respectively; calculate the soil erosion amount in the project crediting period in the baseline scenario and project scenario respectively, and calculate the surface soil sampling thickness in the baseline scenario and project scenario, etc. Finally, calculate the soil and water conservation carbon sink amount of slope conversion to terrace measures. The present invention solves the problems existing in the prior art that the carbon emission reduction benefit of slope conversion to terrace measures on soil is not considered, and when calculating the soil carbon storage, the surface soil eroded by soil erosion is not deducted, thus underestimating the soil and water conservation carbon sink amount of slope conversion to terrace measures, perfects the soil and water conservation carbon sink mechanism of slope conversion to terrace measures, and more systematically, comprehensively, objectively and accurately estimates the soil and water conservation carbon sink amount of slope conversion to terrace measures.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil and water conservation carbon sinks, and specifically relates to a method for evaluating the soil and water conservation carbon sink amount of slope-to-terrace measures. Background Art

[0002] Under the background of global warming and China's achievement of the dual-carbon goal, all walks of life are actively committed to research on reducing carbon emissions and increasing carbon sink amounts. As an important soil and water conservation measure, slope-to-terrace has produced significant benefits in preventing soil erosion, reducing carbon emissions caused by soil erosion, and increasing soil carbon sink amounts. At present, research on the soil carbon sequestration benefits of slope-to-terrace has emerged, but the existing research is not clear enough about the soil and water conservation carbon sink mechanism of slope-to-terrace, lacks a systematic and comprehensive accounting method for the soil and water conservation carbon sink amount of slope-to-terrace measures, and does not consider the emission reduction benefits of soil and water conservation measures. When calculating the soil carbon storage, the surface soil eroded by soil erosion is not deducted, underestimating the soil and water conservation carbon sink amount of slope-to-terrace measures. Studying the evaluation method of the soil and water conservation carbon sink amount of slope-to-terrace measures is of great significance for objectively evaluating the soil and water conservation carbon sink benefits of slope-to-terrace measures, exploring the huge emission reduction and carbon sink increase benefits of the soil carbon pool, and promoting the inclusion of soil and water conservation measure carbon sinks in CCER trading. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for evaluating the soil and water conservation carbon sink amount of slope-to-terrace measures, which solves the problems in the prior art of not considering the emission reduction benefits of soil and water conservation measures and underestimating the carbon sink amount of soil and water conservation measures.

[0004] The technical solution adopted by the present invention is that the method for evaluating the soil and water conservation carbon sink amount of slope-to-terrace measures is specifically implemented according to the following steps:

[0005] Step 1: Define the baseline scenario and project scenario of the slope-to-terrace measures;

[0006] Step 2: Measure the bulk density and organic carbon content of the surface soil in the baseline scenario and project scenario at the beginning of the implementation of the slope-to-terrace measures respectively;

[0007] Step 3: Calculate the soil erosion amount during the project crediting period in the baseline scenario and project scenario respectively;

[0008] Step 4: Calculate the surface soil sampling thickness in the baseline scenario and project scenario respectively;

[0009] Step 5: Measure the bulk density and organic carbon content of the soil in each soil layer in the baseline scenario and project scenario respectively;

[0010] Step 6: Calculate the carbon emissions in the baseline scenario and project scenario respectively;

[0011] Step 7: Calculate the carbon storage in the baseline scenario and project scenario respectively;

[0012] Step 8: Calculate the soil and water conservation carbon sink of the slope conversion to terrace measure.

[0013] The features of the present invention also lie in that

[0014] Step 1 is specifically implemented according to the following steps:

[0015] The baseline scenario of the slope conversion to terrace measure is the scenario formed by the sloping cultivated land that has not been built into a level terrace over time without the protection of artificial measures, that is, the sloping cultivated land that has not been built into a level terrace, and naturally changes to a certain state over time with artificial cultivation. The project scenario of the slope conversion to terrace measure is the scenario formed by the sloping cultivated land being built into a level terrace over time. The original landforms of the sloping cultivated land determined as the baseline scenario and the terrace in the project scenario have basically the same slope, slope aspect, and soil type.

[0016] Step 2 is specifically implemented according to the following steps:

[0017] Collect surface soil bulk density samples of the baseline scenario and the project scenario sample plots at the beginning of the implementation of the slope conversion to terrace measure respectively, and measure their soil bulk density and organic carbon content.

[0018] Step 3 is specifically implemented according to the following steps:

[0019] The soil erosion modulus of the baseline scenario is the multi-year average value SE after removing the contribution of the engineering measure factor from the soil erosion modulus grid data in the corresponding annual soil and water loss dynamic monitoring results during the project accounting period BSL,t , and is calculated according to formula (1):

[0020]

[0021] In the formula: SE BSL,i,t represents the average sediment yield per unit area of sloping cultivated land soil erosion within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j represents the grid average value obtained from the soil erosion modulus grid data in the dynamic monitoring results of the jth year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless; E represents the soil and water conservation engineering measure factor.

[0022] The soil erosion modulus of the project scenario is the multi-year average value SE of the erosion modulus grid data in the corresponding annual soil and water loss dynamic monitoring results during the project accounting period PROJ,t , and is calculated according to formula (2):

[0023]

[0024] In the formula: SE PROJ,tIndicates the amount of sediment generated by soil erosion in terraced fields per unit area within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j Indicates the grid average obtained from the soil erosion modulus grid data in the dynamic monitoring results of the jth year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless.

[0025] Step 4 is specifically implemented according to the following steps:

[0026] Under the baseline scenario, sediment migration occurs in the surface soil of sloping farmland due to soil erosion, resulting in a reduction in soil layer thickness. The reduction in soil layer thickness is calculated according to formula (3):

[0027] H BSL,SE,t = SE BSL,t × t × ρ BSL,1，0 × 100 (3)

[0028] In the formula: H BSL,SE,t Indicates the average reduction in soil thickness under the baseline scenario within t years, with the unit of centimeters, cm; t represents the number of years since the start of the project, dimensionless; SE BSL,t Indicates the amount of sediment generated by soil erosion in sloping farmland per unit area within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; ρ BSL,1,0 Indicates the bulk density of the first layer of soil in sloping farmland, with the unit of grams per cubic centimeter, g·cm -3 .

[0029] The sampling depth of the first soil layer under the baseline scenario is calculated according to formula (4):

[0030] H BSL,1,t = H BSL,1,0 - H BSL,SE,t (4)

[0031] In the formula: H BSL,1，t Indicates the sampling depth of the first soil layer under the baseline scenario in the tth year, with the unit of centimeters (cm); t represents the number of years since the start of the project, dimensionless; H BSL,1，0 Indicates the sampling depth of the first soil layer under the baseline scenario in the year when the project is completed, with the unit of centimeters (cm); H BSL,SE,t Indicates the average reduction in soil thickness under the baseline scenario within t years, with the unit of centimeters (cm).

[0032] Under the project scenario, sediment migration occurs in the surface soil of terraced fields due to soil erosion, resulting in a reduction in soil layer thickness. The reduction in soil layer thickness is calculated according to formula (5):

[0033]

[0034] In the formula: H PROJ,SE,t represents the average reduced thickness of the soil in the project scenario within t years, in centimeters (cm); t represents the number of years since the start of the project, dimensionless; SE PROJ,t represents the sediment yield generated by soil erosion per unit area of terraced fields within t years, in tons per hectare per year (t·hm -2 a -1 ; ρ PROJ,1,0 represents the bulk density of the first layer of soil in the terraced fields in the year when the project is completed, in grams per cubic centimeter (g·cm -3 .

[0035] The depth of the first soil layer in the project scenario is calculated according to formula (6):

[0036] H PROJ,1,t = H PROJ,1,0 - H PROJ ,SE,t (6)

[0037] In the formula: H PROJ,1，t represents the sampling depth of the first soil layer in the project scenario in the t-th year, in centimeters (cm); t represents the number of years since the start of the project, dimensionless; H PROJ,1，0 represents the sampling depth of the first soil layer in the project scenario in the year when the project is completed, in centimeters (cm); H PROJ,SE,t represents the average reduced thickness of the soil in the project scenario within t years, in centimeters (cm).

[0038] Step 5 is specifically implemented according to the following steps:

[0039] According to the soil layer thickness determined in Step 4, soil samples of each soil layer in the baseline scenario and the project scenario are collected respectively and taken back to the laboratory for testing.

[0040] Step 6 is specifically implemented according to the following steps:

[0041] In the baseline scenario, during the transportation of sediment generated by soil erosion on sloping cultivated land, organic matter decomposes and mineralizes, emitting CO2 into the atmosphere. The carbon emissions in the baseline scenario are calculated according to formula (7):

[0042]

[0043] In the formula: C BSL,t represents the carbon emissions in the baseline scenario within t years, in tons of carbon dioxide equivalent (t CO2e); t represents the number of years since the start of the project, dimensionless; SE BSL,t represents the average sediment yield generated by soil erosion per unit area of sloping cultivated land within t years, in tons per hectare per year (t·hm -2 a-1 ; AREA represents the area of the field block, with the unit of hectare, hm 2 ; SOC BSL,1,0 represents the soil organic carbon content in the first soil layer of the sloping cultivated land, with the unit of grams per kilogram, g·kg -1 ; P represents the decomposition ratio of the organic carbon in the sediment generated by soil erosion during the transportation process, with the unit of %.

[0044] In the project scenario, during the transportation of the sediment generated by soil erosion in the terraced fields, the organic matter will decompose and mineralize, emitting CO2 into the atmosphere. The project carbon emissions are calculated according to formula (8):

[0045]

[0046] In the formula: C PROJ,t represents the project scenario carbon emissions within t years, with the unit of tons of carbon dioxide equivalent, t CO2e; t represents the number of years since the start of the project, dimensionless; SE PROJ,t represents the sediment volume generated by soil erosion per unit area of the terraced fields within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; AREA represents the area of the project field block, with the unit of hectare, hm 2 ; SOC PROJ,1,0 represents the soil organic carbon content in the first soil layer of the terraced fields in the year when the project is completed, with the unit of grams per kilogram, g·kg -1 ; P represents the decomposition ratio of the organic carbon in the sediment generated by soil erosion during the transportation process, with the unit of %.

[0047] Step 7 is specifically implemented according to the following steps:

[0048] The carbon storage in the baseline scenario in the t-th year is calculated according to formula (9):

[0049]

[0050] In the formula: CS BSL,t represents the carbon storage in the baseline scenario in the t-th year, with the unit of tons of carbon dioxide equivalent, tCO2e; l represents the number of layers of stratified sampling in the baseline scenario, i = 1, 2, 3,... dimensionless; AREA represents the area of the field block, with the unit of hectare, hm 2 ; H BSL,l,t represents the soil sampling depth of the l-th layer in the baseline scenario in the t-th year of the project, with the unit of centimeter, cm; ρ BSL,l,t represents the soil bulk density of the l-th layer in the baseline scenario in the t-th year, with the unit of grams per cubic centimeter, g·cm -3 ; SOC BSL,l,ti represents the soil organic carbon content of the l-th layer in the baseline scenario in the t-th year, with the unit of grams per kilogram, g·kg -1 ;

[0051] The carbon storage in the project scenario in the t-th year is calculated according to formula (10):

[0052]

[0053] Where: CS PROJ,t represents the carbon storage in the project scenario in the t-th year, in tons of carbon dioxide equivalent, tCO2e; l represents the number of layers of stratified sampling in the project scenario, i = 1, 2, 3,... dimensionless; AREA represents the field area, in hectares, hm 2 ; H PROJ,l,t represents the soil sampling depth of the l-th layer in the project scenario in the t-th year, in centimeters, cm; ρ PROJ,l,t represents the soil bulk density of the l-th layer in the project scenario in the t-th year, in grams per cubic centimeter, g·cm -3 ; SOC PROJ,l,t represents the soil organic carbon content of the l-th layer in the project scenario in the t-th year, in grams per kilogram, g·kg -1 .

[0054] Step 8 is specifically implemented according to the following steps:

[0055] The soil and water conservation carbon sink volume after implementing the slope-to-terrace measure for t years is calculated according to formula (11):

[0056] CDR t =(C BSL,t -C PROJ,t )+(CS PROJ,t -CS BSL,t ) (11)

[0057] Where: CDR t represents the soil and water conservation carbon sink volume after implementing the project for t years, in tons of carbon dioxide equivalent, t CO2e; C BSL，t represents the baseline emissions in the t-th year, in tons of carbon dioxide equivalent, t CO2e; C PROJ,t represents the project emissions in the t-th year, in tons of carbon dioxide equivalent, t CO2e; CS BSL represents the baseline carbon storage in the t-th year, in tons of carbon dioxide equivalent, t CO2e; CS PROJ represents the project carbon storage in the t-th year, in tons of carbon dioxide equivalent, t CO2e.

[0058] The beneficial effects of the present invention are as follows. Compared with the existing methods for evaluating the soil and water conservation carbon sink volume of slope conversion to terrace measures, the method of the present invention adds the calculation of the soil carbon emission reduction amount of slope conversion to terrace measures, that is, preventing soil erosion and reducing the carbon emissions generated by soil erosion; when calculating the soil carbon storage, the surface soil eroded by soil erosion is deducted; the soil and water conservation carbon sink mechanism of slope conversion to terrace measures is improved, and the soil and water conservation carbon sink volume of slope conversion to terrace measures is estimated more systematically, comprehensively, objectively and accurately. This method is of great significance for objectively evaluating the soil and water conservation carbon sink benefits of slope conversion to terrace measures, exploring the huge emission reduction and carbon sink benefits of the soil carbon pool, and promoting the inclusion of the carbon sink of soil and water conservation measures in CCER trading. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 are the method steps for the present invention to evaluate the soil and water conservation carbon sink volume of slope conversion to terrace measures;

[0060] Figure 2 is a schematic diagram of the soil layer depth division in different monitoring periods of the method for the present invention to evaluate the soil and water conservation carbon sink volume of slope conversion to terrace measures. DETAILED DESCRIPTION OF THE INVENTION

[0061] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0062] The method for the present invention to evaluate the soil and water conservation carbon sink volume of slope conversion to terrace measures, the flowchart is as Figure 1 shown, and the specific implementation steps are as follows:

[0063] Step 1: Define the baseline scenario and project scenario of the slope conversion to terrace measures;

[0064] Step 1 is specifically implemented according to the following steps:

[0065] The baseline scenario of the slope conversion to terrace measures is the scenario formed by the sloping cultivated land that has not been built into a horizontal terrace over time without artificial measure protection, that is, the sloping cultivated land that has not been built into a horizontal terrace, and changes naturally to a certain state over time with artificial cultivation. The project scenario of the slope conversion to terrace measures is the scenario formed by the sloping cultivated land being built into a horizontal terrace over time. The original landforms of the sloping cultivated land determined as the baseline scenario and the terraced fields in the project scenario have basically the same slope, aspect, and soil type.

[0066] Step 2: Measure the bulk density and organic carbon content of the surface soil in the baseline scenario and project scenario at the beginning of the implementation of the slope conversion to terrace measures respectively;

[0067] Step 2 is specifically implemented according to the following steps:

[0068] Collect the bulk density samples of the surface soil in the baseline scenario and project scenario at the beginning of the implementation of the slope conversion to terrace measures respectively, and measure their bulk density and organic carbon content.

[0069] Step 3: Calculate the soil erosion amounts in the project accounting period for the baseline scenario and the project scenario respectively;

[0070] Step 3 is specifically implemented according to the following steps:

[0071] The soil erosion modulus of the baseline scenario is the multi-year average SE after removing the contribution of the engineering measure factor from the soil erosion modulus grid data in the corresponding annual soil and water loss dynamic monitoring results during the project accounting period BSL,t , and it is calculated according to formula (1):

[0072]

[0073] In the formula: SE BSL,i,t represents the average sediment yield per unit area of sloping cultivated land due to soil erosion within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j represents the grid average obtained from the soil erosion modulus grid data in the dynamic monitoring results of the jth year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless; E represents the soil and water conservation engineering measure factor.

[0074] The soil erosion modulus of the project scenario is the multi-year average SE of the erosion modulus grid data in the corresponding annual soil and water loss dynamic monitoring results during the project accounting period PROJ,t , and it is calculated according to formula (2):

[0075]

[0076] In the formula: SE PROJ,t represents the sediment yield per unit area of terraced fields due to soil erosion within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j represents the grid average obtained from the soil erosion modulus grid data in the dynamic monitoring results of the jth year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless.

[0077] Step 4: Calculate the surface soil sampling thicknesses for the baseline scenario and the project scenario respectively;

[0078] Step 4 is specifically implemented according to the following steps:

[0079] In the baseline scenario, due to sediment migration caused by soil erosion on the surface soil of sloping cultivated land, the soil layer thickness decreases, and the reduction amount of the soil layer thickness is calculated according to formula (3):

[0080] H BSL,SE,t = SE BSL,t × t × ρ BSL,1，0 × 100 (3)

[0081] Where: H BSL,SE,t represents the average reduced thickness of the soil in the baseline scenario within t years, in centimeters, cm; t represents the number of years since the start of the project, dimensionless; SE BSL,t represents the sediment yield per unit area of sloping cultivated land due to soil erosion within t years, in tons per hectare per year, t·hm -2 a -1 ; ρ BSL,1,0 represents the bulk density of the first layer of soil in sloping cultivated land, in grams per cubic centimeter, g·cm -3 .

[0082] The sampling depth of the first soil layer in the baseline scenario is calculated according to formula (4):

[0083] H BSL,1,t = H BSL,1,0 - H BSL,SE,t (4)

[0084] Where: H BSL,1，t represents the sampling depth of the first soil layer in the baseline scenario in the t-th year, in centimeters (cm); t represents the number of years since the start of the project, dimensionless; H BSL,1，0 represents the sampling depth of the first soil layer in the baseline scenario in the year when the project is completed, in centimeters (cm); H BSL,SE,t represents the average reduced thickness of the soil in the baseline scenario within t years, in centimeters (cm).

[0085] In the project scenario, sediment migration occurs in the surface soil of the terraced fields due to soil erosion, resulting in a reduction in the soil layer thickness. The reduction in the soil layer thickness is calculated according to formula (5):

[0086]

[0087] Where: H PROJ,SE,t represents the average reduced thickness of the soil in the project scenario within t years, in centimeters, cm; t represents the number of years since the start of the project, dimensionless; SE PROJ,t represents the sediment yield per unit area of the terraced fields due to soil erosion within t years, in tons per hectare per year, t·hm -2 a -1 ; ρ PROJ,1,0 represents the bulk density of the first layer of soil in the terraced fields in the year when the project is completed, in grams per cubic centimeter, g·cm -3 .

[0088] The depth of the first soil layer in the project scenario is calculated according to formula (6):

[0089] H PROJ,1,t = H PROJ,1,0 - H PROJ,SE,t (6)

[0090] In the formula: H PROJ,1，t represents the sampling depth of the first soil layer in the project scenario in the t-th year, with the unit of centimeter (cm); t represents the number of years since the start of the project, dimensionless; H PROJ,1，0 represents the sampling depth of the first soil layer in the project scenario in the year when the project is completed, with the unit of centimeter (cm); H PROJ,SE,t represents the average reduced thickness of the soil in the project scenario within t years, with the unit of centimeter (cm).

[0091] Step 5: Measure the soil bulk density and organic carbon content of each soil layer in the baseline scenario and the project scenario respectively;

[0092] Step 5 is specifically implemented according to the following steps:

[0093] According to the soil layer thickness determined in Step 4, collect soil samples from each soil layer in the baseline scenario and the project scenario respectively, and bring them back to the laboratory for testing.

[0094] Step 6: Calculate the carbon emissions in the baseline scenario and the project scenario respectively;

[0095] Step 6 is specifically implemented according to the following steps:

[0096] In the baseline scenario, during the transportation of the sediment generated by soil erosion on the sloping cultivated land, the organic matter decomposes and mineralizes, and CO2 is emitted into the atmosphere. The carbon emissions in the baseline scenario are calculated according to formula (7):

[0097]

[0098] In the formula: C BSL,t represents the carbon emissions in the baseline scenario within t years, with the unit of ton of carbon dioxide equivalent, t CO2e; t represents the number of years since the start of the project, dimensionless; SE BSL,t represents the average sediment yield per unit area of soil erosion on the sloping cultivated land within t years, with the unit of ton per hectare per year, t·hm -2 a -1 ; AREA represents the area of the field block, with the unit of hectare, hm 2 ; SOC BSL,1,0 represents the soil organic carbon content of the first soil layer of the sloping cultivated land, with the unit of gram per kilogram, g·kg -1 ; P represents the decomposition ratio of the organic carbon in the sediment generated by soil erosion during the transportation process, with the unit of %.

[0099] In the project scenario, during the transportation of sediment generated by soil erosion in terraced fields, organic matter will decompose and mineralize, emitting CO2 into the atmosphere. The project's carbon emissions are calculated according to formula (8):

[0100]

[0101] Where: C PROJ,t represents the carbon emissions in the project scenario within t years, in tons of carbon dioxide equivalent, t CO2e; t represents the number of years since the start of the project, dimensionless; SE PROJ,t represents the amount of sediment generated by soil erosion per unit area of terraced fields within t years, in tons per hectare per year, t·hm -2 a -1 ; AREA represents the area of the project plot, in hectares, hm 2 ; SOC PROJ,1,0 represents the soil organic carbon content in the first soil layer of the terraced fields in the year when the project is completed, in grams per kilogram, g·kg -1 ; P represents the decomposition ratio of the organic carbon in the sediment generated by soil erosion during transportation, in %.

[0102] Step 7: Calculate the carbon stocks in the baseline scenario and the project scenario respectively;

[0103] Step 7 is implemented specifically according to the following steps:

[0104] The carbon stock in the baseline scenario in the t-th year is calculated according to formula (9):

[0105]

[0106] Where: CS BSL,t represents the carbon stock in the baseline scenario in the t-th year, in tons of carbon dioxide equivalent, tCO2e; l represents the number of layers of stratified sampling in the baseline scenario, i = 1, 2, 3,... dimensionless; AREA represents the plot area, in hectares, hm 2 ; H BSL,l,t represents the soil sampling depth of the l-th layer in the baseline scenario in the t-th year of the project, in centimeters, cm; ρ BSL,l,t represents the soil bulk density of the l-th layer in the baseline scenario in the t-th year, in grams per cubic centimeter, g·cm -3 ; SOC BSL,l,ti represents the soil organic carbon content of the l-th layer in the baseline scenario in the t-th year, in grams per kilogram, g·kg -1 ;

[0107] The carbon stock in the project scenario in the t-th year is calculated according to formula (10):

[0108]

[0109] Where: CS PROJ,t represents the carbon storage in the t-th year of the project scenario, in tons of carbon dioxide equivalent, tCO2e; l represents the number of layers of stratified sampling in the project scenario, i = 1, 2, 3,... dimensionless; AREA represents the field area, in hectares, hm 2 ; H PROJ,l,t represents the soil sampling depth of the l-th layer in the project scenario in the t-th year, in centimeters, cm; ρ PROJ,l,t represents the soil bulk density of the l-th layer in the project scenario in the t-th year, in grams per cubic centimeter, g·cm -3 ; SOC PROJ,l,t represents the soil organic carbon content of the l-th layer in the project scenario in the t-th year, in grams per kilogram, g·kg -1 .

[0110] Step 8. Calculate the soil and water conservation carbon sink volume of the slope conversion to terrace measure.

[0111] Step 8 is specifically implemented according to the following steps:

[0112] The soil and water conservation carbon sink volume of the slope conversion to terrace measure implemented for t years is calculated according to formula (11):

[0113] CDR t =(C BSL,t -C PROJ,t )+(CS PROJ,t -CS BSL,t ) (11)

[0114] Where: CDR t represents the soil and water conservation carbon sink volume of the project implemented for t years, in tons of carbon dioxide equivalent, t CO2e; C BSL，t represents the baseline emissions in the t-th year, in tons of carbon dioxide equivalent, t CO2e; C PROJ,t represents the project emissions in the t-th year, in tons of carbon dioxide equivalent, t CO2e; CS BSL represents the baseline carbon storage in the t-th year, in tons of carbon dioxide equivalent, t CO2e; CS PROJ represents the project carbon storage in the t-th year, in tons of carbon dioxide equivalent, t CO2e.

[0115] Example 1

[0116] The method for evaluating the soil and water conservation carbon sink volume of the slope conversion to terrace measure of the present invention is specifically implemented according to the following steps:

[0117] Step 1. Define the baseline scenario and project scenario of the slope conversion to terrace measure;

[0118] Step 2. Measure the surface soil bulk density and organic carbon content of the baseline scenario and project scenario at the beginning of the implementation of the slope conversion to terrace measure respectively;

[0119] Step 3: Calculate the soil erosion amounts of the baseline scenario and the project scenario during the project crediting period respectively;

[0120] Step 4: Calculate the surface soil sampling thicknesses of the baseline scenario and the project scenario respectively;

[0121] Step 5: Measure the soil bulk density and organic carbon content of each soil layer in the baseline scenario and the project scenario respectively;

[0122] Step 6: Calculate the carbon emission amounts of the baseline scenario and the project scenario respectively;

[0123] Step 7: Calculate the carbon storage amounts of the baseline scenario and the project scenario respectively;

[0124] Step 8: Calculate the soil and water conservation carbon sink amount of the slope conversion to terrace measure.

[0125] Example 2

[0126] The method for evaluating the soil and water conservation carbon sink amount of the slope conversion to terrace measure of the present invention is specifically implemented according to the following steps:

[0127] Step 1: Define the baseline scenario and the project scenario of the slope conversion to terrace measure;

[0128] Step 1 is specifically implemented according to the following steps:

[0129] The baseline scenario of the slope conversion to terrace measure is the scenario formed by the sloping farmland that has not been built into a horizontal terrace over time without artificial measure protection, that is, the sloping farmland that has not been built into a horizontal terrace changes naturally to a certain state over time with artificial cultivation. The project scenario of the slope conversion to terrace measure is the scenario formed by the sloping farmland being built into a horizontal terrace over time. The original landforms of the sloping farmland determined as the baseline scenario and the terraced fields of the project scenario have basically the same slope, slope aspect, and soil type.

[0130] Step 2: Measure the surface soil bulk density and organic carbon content of the baseline scenario and the project scenario at the beginning of the implementation of the slope conversion to terrace measure respectively;

[0131] Step 2 is specifically implemented according to the following steps:

[0132] Collect surface soil bulk density samples of the baseline scenario and the project scenario at the beginning of the implementation of the slope conversion to terrace measure respectively, and measure their soil bulk density and organic carbon content.

[0133] Step 3: Calculate the soil erosion amounts of the baseline scenario and the project scenario during the project crediting period respectively;

[0134] Step 3 is specifically implemented according to the following steps:

[0135] The baseline scenario soil erosion modulus is the multi-year average SE after removing the contribution of engineering measures factors from the soil erosion modulus grid data in the dynamic soil and water loss monitoring results for the corresponding years during the project inclusion period. BSL,t , calculated according to formula (1):

[0136]

[0137] In the formula: SE BSL,i,t represents the average sediment yield per unit area of sloping farmland due to soil erosion within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j represents the grid average obtained from the soil erosion modulus grid data in the dynamic monitoring results for the jth year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless; E represents the soil and water conservation engineering measures factor.

[0138] The project scenario soil erosion modulus is the multi-year average SE of the erosion modulus grid data in the dynamic soil and water loss monitoring results for the corresponding years during the project inclusion period. PROJ,t , calculated according to formula (2):

[0139]

[0140] In the formula: SE PROJ,t represents the sediment yield per unit area of terraced fields due to soil erosion within t years, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j represents the grid average obtained from the soil erosion modulus grid data in the dynamic monitoring results for the jth year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless.

[0141] Step 4: Calculate the surface soil sampling thickness for the baseline scenario and the project scenario respectively;

[0142] Step 4 is specifically implemented according to the following steps:

[0143] In the baseline scenario, due to sediment migration caused by soil erosion on the surface soil of sloping farmland, the soil layer thickness decreases, and the amount of soil layer thickness reduction is calculated according to formula (3):

[0144] H BSL,SE,t =SE BSL,t ×t×ρ BSL,1，0 ×100 (3)

[0145] In the formula: HBSL,SE,t It represents the average reduction thickness of the soil in the baseline scenario over t years, with the unit of centimeter, cm; t represents the number of years since the start of the project, dimensionless; SE BSL,t It represents the sediment yield per unit area of sloping cultivated land due to soil erosion over t years, with the unit of ton per hectare per year, t·hm -2 a -1 ; ρ BSL,1,0 It represents the bulk density of the first layer of soil on sloping cultivated land, with the unit of gram per cubic centimeter, g·cm -3 .

[0146] The sampling depth of the first soil layer in the baseline scenario is calculated according to formula (4):

[0147] H BSL,1,t = H BSL,1,0 - H BSL,SE,t (4)

[0148] In the formula: H BSL,1，t It represents the sampling depth of the first soil layer in the baseline scenario in the t-th year, with the unit of centimeter (cm); t represents the number of years since the start of the project, dimensionless; H BSL,1，0 It represents the sampling depth of the first soil layer in the baseline scenario in the year when the project is completed, with the unit of centimeter (cm); H BSL,SE,t It represents the average reduction thickness of the soil in the baseline scenario over t years, with the unit of centimeter (cm).

[0149] Under the project scenario, sediment migration occurs in the surface soil of the terraced fields due to soil erosion, resulting in a reduction in the soil layer thickness. The reduction amount of the soil layer thickness is calculated according to formula (5):

[0150]

[0151] In the formula: H PROJ,SE,t It represents the average reduction thickness of the soil in the project scenario over t years, with the unit of centimeter, cm; t represents the number of years since the start of the project, dimensionless; SE PROJ,t It represents the sediment yield per unit area of the terraced fields due to soil erosion over t years, with the unit of ton per hectare per year, t·hm -2 a -1 ; ρ PROJ,1,0 It represents the bulk density of the first layer of soil on the terraced fields in the year when the project is completed, with the unit of gram per cubic centimeter, g·cm -3 .

[0152] The depth of the first soil layer in the project scenario is calculated according to formula (6):

[0153] H PROJ,1,t = H PROJ,1,0 - H PROJ,SE,t (6)

[0154] In the formula: HPROJ,1，t represents the sampling depth of the first soil layer in the project scenario in the t-th year, with the unit of centimeter (cm); t represents the number of years since the start of the project, dimensionless; H PROJ,1，0 represents the sampling depth of the first soil layer in the project scenario in the year when the project is completed, with the unit of centimeter (cm); H PROJ,SE,t represents the average reduced thickness of the soil in the project scenario within t years, with the unit of centimeter (cm).

[0155] Step 5: Measure the soil bulk density and organic carbon content of each soil layer in the baseline scenario and the project scenario respectively;

[0156] Step 5 is specifically implemented according to the following steps:

[0157] According to the soil layer thickness determined in Step 4, collect soil samples from each soil layer in the baseline scenario and the project scenario respectively, and bring them back to the laboratory for testing.

[0158] Step 6: Calculate the carbon emissions in the baseline scenario and the project scenario respectively;

[0159] Step 7: Calculate the carbon storage in the baseline scenario and the project scenario respectively;

[0160] Step 7 is specifically implemented according to the following steps:

[0161] The carbon storage in the baseline scenario in the t-th year is calculated according to formula (9):

[0162]

[0163] In the formula: CS BSL,t represents the carbon storage in the baseline scenario in the t-th year, with the unit of ton of carbon dioxide equivalent, tCO2e; l represents the number of layers of stratified sampling in the baseline scenario, i = 1, 2, 3,... dimensionless; AREA represents the field area, with the unit of hectare, hm 2 ; H BSL,l,t represents the sampling depth of the l-th layer of soil in the baseline scenario in the t-th year of the project, with the unit of centimeter, cm; ρ BSL,l,t represents the soil bulk density of the l-th layer of soil in the baseline scenario in the t-th year, with the unit of gram per cubic centimeter, g·cm -3 ; SOC BSL,l,ti represents the soil organic carbon content of the l-th layer of soil in the baseline scenario in the t-th year, with the unit of gram per kilogram, g·kg -1 ;

[0164] The carbon storage in the project scenario in the t-th year is calculated according to formula (10):

[0165]

[0166] In the formula: CS PROJ,tIndicates the carbon storage in the t-th year of the project scenario, in tons of carbon dioxide equivalent, tCO2e; l represents the number of layers of stratified sampling in the project scenario, i = 1, 2, 3,... dimensionless; AREA represents the field area, in hectares, hm 2 ; H PROJ,l,t Indicates the soil sampling depth of the l-th layer in the project scenario in the t-th year, in centimeters, cm; ρ PROJ,l,t Indicates the soil bulk density of the l-th layer in the project scenario in the t-th year, in grams per cubic centimeter, g·cm -3 ; SOC PROJ,l,t Indicates the soil organic carbon content of the l-th layer in the project scenario in the t-th year, in grams per kilogram, g·kg -1 .

[0167] Step 8: Calculate the soil and water conservation carbon sink of the slope-to-terrace measure.

[0168] Step 8 is specifically implemented according to the following steps:

[0169] The soil and water conservation carbon sink of the slope-to-terrace measure implemented for t years is calculated according to formula (11):

[0170] CDR t =(C BSL,t -C PROJ,t )+(CS PROJ,t -CS BSL,t ) (11)

[0171] In the formula: CDR t Indicates the soil and water conservation carbon sink of the project implemented for t years, in tons of carbon dioxide equivalent, t CO2e; C BSL，t Indicates the baseline emissions in the t-th year, in tons of carbon dioxide equivalent, t CO2e; C PROJ,t Indicates the project emissions in the t-th year, in tons of carbon dioxide equivalent, t CO2e; CS BSL Indicates the baseline carbon storage in the t-th year, in tons of carbon dioxide equivalent, t CO2e; CS PROJ Indicates the project carbon storage in the t-th year, in tons of carbon dioxide equivalent, t CO2e.

[0172] Example 3

[0173] In response to the existing demand for evaluating the soil and water conservation carbon sink of slope-to-terrace measures, the present invention provides a method for accurately evaluating the soil and water conservation carbon sink of slope-to-terrace measures by considering the emission reduction benefits and carbon sink enhancement benefits of soil and water conservation measures. Taking the terraced fields built in Wuqi County for 20 years as an example, the steps for evaluating the soil and water conservation carbon sink of slope-to-terrace measures are described:

[0174] Step 1: Define the baseline scenario and project scenario of the slope-to-terrace measure:

[0175] The baseline scenario for the slope-to-terrace measures is the scenario formed by the sloping cultivated land that has not been built into level terraces over time without human protection measures, that is, the sloping cultivated land that has not been built into level terraces and has changed over 20 years with human cultivation. The project scenario is the scenario formed after the sloping cultivated land is built into level terraces and has changed over 20 years. The original landforms of the sloping cultivated land determined as the baseline scenario and the terraces in the project scenario have basically the same slope (15 - 20°), slope aspect (south-facing), and soil type (loessial soil).

[0176] Step 2: Measure the bulk density and organic carbon content of the surface soil in the baseline scenario and the project scenario at the beginning of the implementation of the slope-to-terrace measures respectively:

[0177] Collect the bulk density samples of the surface 20 cm soil in the baseline scenario and the project scenario at the beginning of the implementation of the slope-to-terrace measures respectively, and measure their bulk density. The bulk density ρ of the surface soil in the baseline scenario (sloping cultivated land) BSL,1,0 is 1.19 g·cm -3 , and the organic carbon content SOC of the surface soil BSL,1,0 is 2.53 g·kg -1 ; the bulk density ρ of the surface soil in the project scenario (terrace) PROJ,1,0 is 1.47 g·cm -3 , and the organic carbon content SOC of the surface soil PROJ,1,0 is 2.18 g·kg -1 .

[0178] Step 3: Calculate the soil erosion amounts in the baseline scenario and the project scenario during the project accounting period respectively:

[0179] The soil erosion amount in the baseline scenario after 20 years of project implementation is calculated according to the multi-year average value after removing the contribution of the engineering measure factor from the erosion modulus grid data in the national soil erosion dynamic monitoring results, and SE is calculated according to formula (1) BSL,t is 4393 t·hm -2 a -1 .

[0180] The soil erosion amount in the project scenario after 20 years of project implementation is calculated according to the multi-year average value of the erosion modulus grid data in the national soil erosion dynamic monitoring results, and SE is calculated according to formula (2) PROJ,t is 369 t·hm -2 a -1 .

[0181] Step 4: Calculate the surface soil sampling thickness in the baseline scenario and the project scenario respectively:

[0182] In the baseline scenario, after 20 years, due to sediment migration caused by soil erosion in the sloping cultivated land where the slope-to-terrace measures have not been implemented, the soil layer thickness decreases. Calculate the reduction amount H of the soil layer thickness in the baseline scenario according to formula (3)BSL,SE,t is 7.3 cm. According to formula (4), the sampling depth of the first layer of soil in the sloping cultivated land should be 20 - 7.3 = 12.7 cm. The sampling depths of the second to fifth layers of soil in the baseline scenario are 20 cm respectively.

[0183] Under the project scenario, 20 years after the construction of terraced fields, due to sediment migration caused by soil erosion, the soil layer thickness decreases. According to formula (5), the reduction amount of soil layer thickness H in the project scenario is calculated. PROJ,SE,t is 0.6 cm. According to formula (6), the sampling depth of the first layer of soil should be 20 - 0.5 = 19.5 cm. The sampling depths of the second to fifth layers of soil in the project scenario are 20 cm respectively.

[0184] Step 5: Measure the soil bulk density and organic carbon content of each soil layer in the baseline scenario and the project scenario respectively:

[0185] According to the soil layer thickness requirements in Step 4, collect soil samples from each soil layer in the baseline scenario and the project scenario, and take them back to the laboratory to detect the soil bulk density and organic carbon content of each soil layer.

[0186] Step 6: Calculate the carbon emissions in the baseline scenario and the project scenario respectively:

[0187] Under the baseline scenario, during the transportation of sediment generated by soil erosion on sloping cultivated land, organic matter decomposes and mineralizes, emitting CO2 into the atmosphere. The sample plot area AREA is calculated as 1 hm 2 counted, and the decomposition ratio P of the organic carbon in the sediment generated by soil erosion during transportation is calculated as 30%. According to formula (7), C is calculated as BSL,t 2.45 t CO2e.

[0188] Under the project scenario, during the transportation of sediment generated by soil erosion on terraced fields, organic matter decomposes and mineralizes, emitting CO2 into the atmosphere. The sample plot area AREA is calculated as 1 hm 2 counted, and the decomposition ratio P of the organic carbon in the sediment generated by soil erosion during transportation is calculated as 30%. According to formula (8), C is calculated as PROJ,t 0.18 t CO2e.

[0189] Step 7: Calculate the carbon storage in the baseline scenario and the project scenario respectively:

[0190] Combined with Figure 2 , according to the soil bulk density and soil organic carbon content of each soil layer in the baseline scenario and the project scenario measured in Step 5, the carbon storage of each soil layer (Table 1) and the total carbon storage in the baseline scenario and the project scenario are calculated according to formula (9) and formula (10). Under the baseline scenario, the soil carbon storage CS of 1 hm 2 of land is BSL,t 82.22 t CO2e; under the project scenario, the soil carbon storage of 1 hm2 Soil carbon storage CS of the land PROJ,t is 141.63 t CO2e.

[0191] Table 1 Calculation results of soil carbon storage in the baseline scenario and the project scenario

[0192]

[0193] Step 8: Calculate the soil and water conservation carbon sink of the slope-to-terrace measure:

[0194] For the soil and water conservation carbon sink of the 1 hm field plot after 20 years of implementation of the slope-to-terrace measure 2 The soil and water conservation carbon sink is calculated according to formula (11), and the soil and water conservation carbon sink CDR t is 61.68 t CO2e.

Claims

1. A method for evaluating the soil and water conservation carbon sink volume of slope conversion to terrace measures, characterized in that, The implementation is specifically carried out according to the following steps: Step 1: Define the baseline scenario and project scenario of the slope conversion to terrace measures; Step 2: Measure the bulk density and organic carbon content of the surface soil in the baseline scenario and project scenario at the beginning of the implementation of the slope conversion to terrace measures respectively; Step 3: Calculate the soil erosion amounts in the baseline scenario and project scenario during the project crediting period respectively; The specific implementation of Step 3 is carried out according to the following steps: The baseline scenario soil erosion modulus is the multi-year average value after removing the contribution of engineering measures factors from the soil erosion modulus grid data in the corresponding annual soil and water loss dynamic monitoring results during the project accounting period SE BSL,t , calculated according to formula (1): （1） In the formula: SE BSL, t represents t the average sediment yield per unit area of sloping cultivated land due to soil erosion within a year, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j represents the grid average value obtained from the soil erosion modulus grid data in the annual dynamic monitoring results of the j th year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless; E represents the factor of soil and water conservation engineering measures; The soil erosion modulus of the project scenario is the multi-year average of the erosion modulus grid data in the dynamic soil and water loss monitoring results for the corresponding years during the project accounting period SE PROJ, t , calculated according to formula (2): （2） In the formula: SE PROJ, t represents t the sediment yield per unit area of terraced fields due to soil erosion within a year, with the unit of tons per hectare per year, t·hm -2 a -1 ; A j represents the grid average obtained from the grid data of soil erosion modulus in the annual dynamic monitoring results of the j year, with the unit of tons per hectare per year, t·hm -2 a -1 ; t represents the number of years since the start of the project, dimensionless; Step 4: Calculate the surface soil sampling thicknesses in the baseline scenario and project scenario respectively; The specific implementation of Step 4 is carried out according to the following steps: In the baseline scenario, due to soil erosion, sediment migration occurs in the surface soil of the sloping farmland, resulting in a reduction in soil layer thickness. The reduction amount of the soil layer thickness is calculated according to Formula (3): （3） In the formula: H BSL,SE,t represents t the average reduced thickness of the soil in the baseline scenario within years, in centimeters (cm); t represents the number of years since the start of the project, dimensionless; SE BSL,t represents t the sediment yield per unit area of soil erosion on sloping cultivated land within years, in tons per hectare per year (t·hm -2 a -1 ; ρ BSL,1, 0 represents the bulk density of the first layer of soil on sloping cultivated land, in grams per cubic centimeter (g·cm -3 ; The sampling depth of the first soil layer in the baseline scenario is calculated according to Formula (4): （4） In the formula: H BSL,1，t represents the t year, the sampling depth of the first soil layer in the baseline scenario, in centimeters; t represents the number of years since the start of the project, dimensionless; H BSL,1，0 represents the sampling depth of the first soil layer in the baseline scenario in the year when the project is completed, in centimeters; H BSL,SE,t represents t within the year, the average reduction thickness of the soil in the baseline scenario, in centimeters; In the project scenario, due to soil erosion, sediment migration occurs in the surface soil of the terrace, resulting in a reduction in soil layer thickness. The reduction amount of the soil layer thickness is calculated according to Formula (5): （5） In the formula: H PROJ, SE, t represents t the average reduced thickness of the soil in the project scenario within years, in centimeters (cm); t represents the number of years since the start of the project, dimensionless; SE PROJ, t represents t the sediment yield per unit area of soil erosion in the terraced fields within years, in tons per hectare per year (t·hm -2 a -1 ; ρ PROJ, 1,0 represents the bulk density of the first layer of soil in the terraced fields in the year when the project is completed, in grams per cubic centimeter (g·cm -3 ; The depth of the first soil layer in the project scenario is calculated according to Formula (6): （6） In the formula: H PROJ,1，t represents the t year, the sampling depth of the first soil layer in the project scenario, in centimeters (cm); t represents the number of years since the start of the project, dimensionless; H PROJ,1，0 represents the sampling depth of the first soil layer in the project scenario in the year of project completion, in centimeters (cm); H PROJ, SE, t represents t within years, the average reduced thickness of the soil in the project scenario, in centimeters; Step 5: Measure the bulk density and organic carbon content of the soil in each soil layer in the baseline scenario and project scenario respectively; The specific implementation of Step 5 is carried out according to the following steps: According to the soil layer thickness determined in Step 4, collect soil samples from each soil layer in the baseline scenario and project scenario respectively for testing; Step 6: Calculate the carbon emissions in the baseline scenario and project scenario respectively; The specific implementation of Step 6 is carried out according to the following steps: In the baseline scenario, during the transportation of the sediment generated by soil erosion in the sloping farmland, the organic matter decomposes and mineralizes, emitting CO2 into the atmosphere. The carbon emissions in the baseline scenario are calculated according to Formula (7): （7） In the formula: C BSL, t represents t the carbon emissions in the baseline scenario within t years, in tons of carbon dioxide equivalent, t CO2e; t represents the number of years since the start of the project, dimensionless; SE BSL, t represents the average sediment yield per unit area of sloping cultivated land due to soil erosion within t years, in tons per hectare per year, t·hm -2 a -1 ; AREA represents the area of the field plot, in hectares, hm 2 ; SOC BSL, 1, 0 represents the soil organic carbon content in the first soil layer of the sloping cultivated land, in grams per kilogram, g·kg -1 ; P represents the decomposition ratio of the sediment organic carbon generated by soil erosion during transportation, in %; In the project scenario, during the transportation of the sediment generated by soil erosion in the terrace, the organic matter decomposes and mineralizes, emitting CO2 into the atmosphere. The project carbon emissions are calculated according to Formula (8): （8） Where: C PROJ, t represents t the project scenario carbon emissions within [X] years, in tons of carbon dioxide equivalent, t CO2e; t the number of years since the start of the project, dimensionless; SE PROJ,t represents t the sediment yield per unit area of terraced fields due to soil erosion within [X] years, in tons per hectare per year, t·hm -2 a -1 ; AREA represents the area of the project plot, in hectares, hm 2 ; SOC PROJ, 1, 0 represents the soil organic carbon content in the first soil layer of the terraced fields in the year when the project is completed, in grams per kilogram, g·kg -1 ; P represents the decomposition ratio of the organic carbon in the sediment generated by soil erosion during transportation, in %; Step 7: Calculate the carbon stocks in the baseline scenario and project scenario respectively; The specific implementation of Step 7 is carried out according to the following steps: Baseline scenario No. t The annual carbon stock is calculated according to Equation (9): （9） In the formula: CS BSL, t represents the carbon stock in the baseline scenario in the t th year, with the unit of ton of carbon dioxide equivalent, t CO2e; l represents the number of layers of stratified sampling in the baseline scenario, i = 1, 2, 3, … dimensionless; AREA represents the plot area, with the unit of hectare, hm 2 ; H BSL, l, t represents the t th year of the project, and the soil sampling depth of the l th layer in the baseline scenario, with the unit of centimeter, cm; ρ BSL, l, t represents the t th year, and the soil bulk density of the l th layer in the baseline scenario, with the unit of gram per cubic centimeter, g·cm -3 ; SOC BSL, l, t i represents the soil organic carbon content of the t th year and the l th layer in the baseline scenario, with the unit of gram per kilogram, g·kg -1 ; The carbon stock in the project scenario in the t-th year is calculated according to Formula (10): （10） Where: CS PROJ, t represents the carbon storage in the project scenario in the t th year, in tons of carbon dioxide equivalent, t CO2e; l represents the number of layers of stratified sampling in the project scenario, i = 1, 2, 3,... dimensionless; AREA represents the field area, in hectares, hm 2 ; H PROJ,l, t represents the t th year, the soil sampling depth of the l th layer in the project scenario, in centimeters, cm; ρ PROJ, l, t represents the t th year, the soil bulk density of the l th layer in the project scenario, in grams per cubic centimeter, g·cm -3 ; SOC PROJ, l, t represents the t th year, the soil organic carbon content of the l th layer in the project scenario, in grams per kilogram, g·kg -1 ; Step 8: Calculate the soil and water conservation carbon sink amount of the slope conversion to terrace measures; The specific implementation of Step 8 is carried out according to the following steps: Implementation of slope conversion to terraced field measures t The soil and water conservation carbon sink amount in year is calculated according to formula (11): （11） Where: CDR t represents the soil and water conservation carbon sink volume in t year, with the unit of ton of carbon dioxide equivalent, t CO2e; C BSL，t represents t the baseline emissions in C PROJ, t year, with the unit of ton of carbon dioxide equivalent, t CO2e; t represents the project emissions in CS BSL year, with the unit of ton of carbon dioxide equivalent, t CO2e; t represents the baseline carbon storage in CS PROJ year, with the unit of ton of carbon dioxide equivalent, tCO2e; t represents the project carbon storage in year, with the unit of ton of carbon dioxide equivalent, t CO2e.

2. The method for evaluating the soil and water conservation carbon sink volume of the slope-to-terrace measures according to claim 1, wherein, The specific implementation of Step 1 is carried out according to the following steps: The baseline scenario of the slope conversion to terrace measures is the scenario formed by the sloping farmland that has not been built into a horizontal terrace over time without human protection measures, that is, the sloping farmland that has not been built into a horizontal terrace changes naturally to a certain state with human cultivation. The project scenario of the slope conversion to terrace measures is the scenario formed by the sloping farmland being built into a horizontal terrace over time. The original landforms of the sloping farmland determined as the baseline scenario and the terrace in the project scenario have the same slope, slope aspect, and soil type.

3. The method for evaluating the soil and water conservation carbon sink of slope conversion to terrace measures according to claim 2, characterized in that, The specific implementation of Step 2 is carried out according to the following steps: Collect surface soil bulk density samples from the sample plots in the baseline scenario and project scenario at the beginning of the implementation of the slope conversion to terrace measures respectively, and measure the soil bulk density and organic carbon content.

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