Evaluation method for carbon sequestration effect of fertilizer

Abstract

The invention discloses an evaluation method for a carbon sequestration effect of a fertilizer, and belongs to the technical field of agriculture, the evaluation method comprises the following steps: selecting a representative plot, collecting a soil sample by a multi-point sampling method, and marking the soil sample; grinding the soil sample in a laboratory environment until the particle size is less than 0.5 mm; transferring the soil sample into a constant-temperature oven for drying, and weighing a certain mass of soil sample; placing the soil sample in a thermogravimetric analyzer for thermogravimetric analysis, continuously recording a mass change curve of the soil sample, determining two characteristic temperature intervals according to the mass change curve, calculating the mass loss rate of the soil sample in the characteristic temperature intervals, and calculating a comprehensive carbon sequestration intensity index Z; and comparing the parameter indexes Z of the soil samples subjected to fertilization and not subjected to fertilization to complete evaluation of the carbon sequestration effect. The method can rapidly and accurately evaluate the carbon sequestration effect of the fertilizer, and can adapt to different environmental conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of agriculture, and particularly relates to a method for evaluating the carbon sequestration effect of fertilizers. Background Art

[0002] Fertilizers refer to substances that can provide one or more essential nutrient elements for plants, improve soil properties, increase soil fertility, and thus promote the growth and development of plants. The carbon sequestration effect refers to the ability of fertilizers to fix carbon dioxide in the atmosphere through chemical or biological actions in the soil. Evaluating the carbon sequestration effect of fertilizers is of great significance for improving fertilizer utilization efficiency and reducing greenhouse gas emissions. In the prior art, the methods for evaluating the carbon sequestration effect of fertilizers mainly rely on field trials, which are time-consuming and difficult to accurately reflect the carbon sequestration effect of fertilizers under different environmental conditions. Summary of the Invention

[0003] Technical Problem to be Solved: Aiming at the technical problems existing in the method for evaluating the carbon sequestration effect of fertilizers in the background art, the present invention provides a method for evaluating the carbon sequestration effect of fertilizers, which can quickly and accurately evaluate the carbon sequestration effect of fertilizers and can adapt to different environmental conditions.

[0004] Technical Solution: A method for evaluating the carbon sequestration effect of fertilizers according to the present invention, the evaluation method includes the following steps: Step 1: When collecting soil samples, select representative plots, and collect soil by multi-point sampling method in the fertilized area and the non-fertilized area respectively. Transfer the collected soil samples to sealed bags and make marks. Step 2: Under laboratory conditions, grind the soil samples to a particle size less than 0.5 mm. Step 3: After grinding, transfer the soil samples to a constant temperature oven and dry them to the required dryness; weigh a certain mass of soil samples, and the soil samples after fertilization treatment are denoted as M 施肥 , and the soil samples without fertilization treatment are denoted as M 原始 ; Step 4: Place the soil samples in a thermogravimetric analyzer. The thermogravimetric analysis process of the thermogravimetric analyzer is set to heat from room temperature to 900 °C at a heating rate of 10 °C / min; start the thermogravimetric analyzer to perform thermogravimetric analysis on the soil samples. During the heating process, the sensor of the thermogravimetric analyzer continuously records the mass change curve of the soil samples, and the mass change curve W 施肥 of the soil sample M t，施肥 and the mass change curve W 原始 of the soil sample M t，原始 are obtained through the data acquisition system, where t is the temperature / °C; Step 5: Based on the mass change curve, determine two characteristic temperature intervals: (1) Thermally decompose the carbonate compounds in the soil sample in the range of 300 - 600 °C, and calculate the mass loss rate Δm 施肥 of the soil sample M 1，施肥 and the mass loss rate Δm 原始 of the soil sample M 1，原始 . The calculation formula is as follows: Δm1 = (M - M 300~600℃ ) / M × 100%; In the formula, M is the initial mass of the soil sample, and M 300~600℃ is the mass of the soil sample at the end of the range of 300 - 600 °C; (2) Thermally decompose the stable carbon-containing substances formed after the fertilizer in the soil sample adsorbs and absorbs carbon dioxide in the range of 600 - 900 °C, and calculate the soil mass loss rate Δm 施肥 of the soil sample M 2，施肥 and the soil mass loss rate Δm 原始 of the soil sample M 2，原始 . The calculation formula is as follows: Δm2 = (M 300~600℃ - M 600~900℃ ) / M × 100%; In the formula, M 300~600℃ is the mass of the soil sample at the end of the range of 300 - 600 °C, and M 600~900℃ is the mass of the soil sample at the end of the range of 600 - 900 °C; Step 6: Calculate the comprehensive carbon sequestration intensity index Z. The calculation formula is as follows: Z = 0.4 * (Δm 1，施肥 - Δm 1，原始 ) + 0.6 * (Δm 2，施肥 - Δm 2，原始 ); Step 7: Compare the parameter index Z of the soil samples with and without fertilization, and complete the evaluation of the carbon sequestration effect.

[0005] Preferably, when selecting a representative plot in Step 1, the following multiple factors are comprehensively considered for selection: (1) Agricultural planting area: To study the carbon sequestration of the soil of food crops by fertilization, select farmlands with typical planting patterns, that is, plots with a single planting variety, uniform planting density, and conventional farming operations; (2) Acidic soil: Select plots with a pH value of 4.5 - 6.5, clay or loam clay texture, acid-tolerant vegetation, and a slope of less than 5°; (3) Natural ecological area: For the study of forest soil, select plots in mature forest areas, with a canopy density of 0.6 - 0.8, rich understory vegetation, distinct soil horizons, and a moderate humus layer.

[0006] Preferably, the specific operation of the multi-point sampling method in step 1 is as follows: (1) Divide the plot evenly into several square or rectangular grid areas of the same size, and set the center position or the intersection of the diagonals of each grid area as the sampling point; (2) After determining the sampling points, use a special soil sampling tool to collect soil at a depth of 0 - 20 cm or 0 - 30 cm; Vertically insert the special soil sampling tool at each sampling point, slowly rotate and press down to collect sufficient soil, then put the soil collected from each sampling point into a sealed bag respectively, make good marks, and indicate the sampling point position and the information of the fertilization treatment to which it belongs.

[0007] Preferably, when using a grinder to grind the soil sample in step 2, the grinding time is controlled within 10 - 15 min, and the grinder is cleaned intermittently during the grinding process.

[0008] Preferably, the oven temperature in step 3 is 40 - 50 °C, and the drying time is controlled within 8 - 12 h.

[0009] Preferably, the thermogravimetric analyzer is calibrated before testing, and the calibration gas is high-purity nitrogen, and its flow rate is controlled within 20 - 30 ml / min.

[0010] Preferably, when determining the characteristic temperature range in step 5, the temperature error is controlled within the range of ±10 °C, and at the same time, the mass change curve is smoothed and outliers are removed.

[0011] Preferably, the specific criteria for evaluating the carbon sequestration effect in step 7 are as follows: (1) If 0% < Z ≤ 0.65%, it is considered that the fertilization treatment method is ineffective for carbon sequestration, indicating that the fertilizer fails to play an effective role in carbon sequestration in this soil environment; (2) If the Z value of the soil sample after fertilization treatment increases significantly compared with the Z value of the soil sample without fertilization treatment, it is considered that the fertilization treatment method is effective for carbon sequestration, and: ① When the soil without fertilization treatment is of acidic soil type, if 0.65% < Z < 1.15%, the carbon sequestration effect of this fertilization treatment method is evaluated as significant; if 1.15% ≤ Z < 1.75%, the carbon sequestration effect of this fertilization treatment method is evaluated as relatively significant; if 1.75% ≤ Z ≤ 100%, the carbon sequestration effect of this fertilization treatment method is evaluated as very significant; ② When the soil without fertilization treatment is of neutral soil type, if 0.65% < Z < 1.25%, the carbon sequestration effect of this fertilization treatment method is evaluated as significant; if 1.25% ≤ Z < 1.85%, the carbon sequestration effect of this fertilization treatment method is evaluated as relatively significant; if 1.85% ≤ Z ≤ 100%, the carbon sequestration effect of this fertilization treatment method is evaluated as very significant; ③When the unfertilized soil is of alkaline soil type, if 0.65% < Z < 1.05%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is significant; if 1.05% ≤ Z < 1.65%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is relatively significant; if 1.65% ≤ Z ≤ 100%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is very significant.

[0012] Preferably, when evaluating the carbon sequestration effect in step 7, if the increase range of the soil Z value after fertilization treatment compared to the soil Z value before fertilization treatment is less than the expected value and close to the measurement error range, it is necessary to repeat the measurement 3 times, take the average value and then conduct the evaluation.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The method of the present invention can quickly and accurately evaluate the carbon sequestration effect of fertilizers and can adapt to different environmental conditions. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the evaluation process for the carbon sequestration effect of the fertilizer of the present invention. Detailed Embodiments

[0015] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some but not all of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention. Figure 1 As shown in the figure, the present invention discloses a method for evaluating the carbon sequestration effect of fertilizers, and the evaluation method includes the following steps.

[0016] As Figure 1 shown, the present invention discloses a method for evaluating the carbon sequestration effect of fertilizers, and the evaluation method includes the following steps.

[0017] (1) When collecting soil samples, select representative plots, and in the fertilized area and the unfertilized area respectively, collect soil samples by the multi-point sampling method, transfer the collected soil samples to sealed bags and make marks to ensure that the samples taken truly reflect the soil characteristics of the selected areas.

[0018] (Ⅰ) When selecting representative plots, the following various factors are comprehensively considered for selection: (1) Agricultural planting areas: Study the carbon sequestration of soil by fertilization for food crops (such as wheat, corn, rice, etc.), and select farmlands with typical planting patterns, that is, plots with single planting varieties, uniform planting densities, and conventional farming operations; (2) Acidic soil: Select a plot with a pH value of 4.5 - 6.5, a clay or loam clay texture, acid-tolerant vegetation (such as tea trees, masson pine, etc.), and a slope less than 5° to exclude the interference of uneven soil nutrients caused by soil erosion on carbon sequestration assessment; (3) Natural ecological area: For forest soil research, select a plot in a mature forest area with a forest canopy density of 0.6 - 0.8, rich understory vegetation, distinct soil horizons, and a moderate humus layer, which can reflect the complete material cycle process of the forest ecosystem.

[0019] (II) The specific operation of the multi-point sampling method is as follows: (1) Divide the plot evenly into several square or rectangular grid areas of the same size, and set the sampling points at the center position or the intersection of the diagonals of each grid area; (2) After determining the sampling points, use a special soil sampling tool (such as a soil drill) to collect soil at a depth of 0 - 20 cm or 0 - 30 cm; vertically insert the soil drill at each sampling point, rotate it slowly and press it down to collect a sufficient amount of soil, then put the soil collected from each sampling point into a sealed bag respectively, make good marks, and indicate key information such as the location of the sampling point and the fertilization treatment situation.

[0020] (III) When collecting soil samples, if the soil pH value < 6.5, the soil is of the acidic soil type; if 6.5 ≤ soil pH value ≤ 7.5, the soil is of the neutral soil type; if the soil pH value > 7.5, the soil is of the alkaline soil type.

[0021] (2) In the laboratory environment, use a high-precision grinder to grind the soil sample to a particle size less than 0.5 mm. The grinding process can ensure uniform heating and sufficient reaction of the soil sample in subsequent experiments. When grinding the soil sample, control the grinding time within 10 - 15 min (the grinding time can be selected as 10 min, 15 min, and any value in between) to ensure that the particle size of the sample is uniformly less than 0.5 mm; at the same time, during the grinding process, clean the grinder intermittently to prevent cross-contamination of soil samples.

[0022] (3) After grinding, transfer the soil sample to a constant-temperature oven and dry it to the required dryness. The oven temperature is 40 - 50 °C (the oven temperature can be selected as 40 °C, 45 °C, 50 °C, and any value in between), and the drying time is controlled within 8 - 12 h to ensure that a large amount of water in the soil sample is discharged, so that the soil sample reaches the appropriate dryness for subsequent experiments, and at the same time, avoid the influence of too high temperature on the composition of the soil sample.

[0023] Weigh a certain mass of the soil sample. The soil sample after fertilization treatment is denoted as M 施肥 , and the soil sample without fertilization treatment is denoted as M 原始; When weighing the soil sample, the fertilizer quality should be considered as an influencing factor: (1) Fertilizers of different masses applied to the soil will bring different degrees of carbon input and trigger different chemical reactions; the nutrients (such as nitrogen, phosphorus, potassium, etc.) and metal ions (calcium, magnesium, etc.) in the fertilizer interact with the soil, affecting the formation and decomposition of carbonate compounds and stable carbon-containing substances. For example, more calcium-containing fertilizers can promote the formation of more calcium carbonate and enhance carbon fixation potential; if the fertilizer mass is high, the components that can participate in carbon fixation reactions will increase accordingly, which may change the soil mass loss rate Δm1 and Δm2 in the two key temperature ranges of thermogravimetric analysis of 300~600℃ and 600~900℃, thereby significantly affecting the calculation results of the comprehensive carbon fixation intensity index Z. The larger the fertilizer mass, the more precursor substances that form stable carbon-containing structures may be contained in it, resulting in different mass loss rates in the same range; (2) In order to accurately evaluate the carbon sequestration gain brought by fertilizers, the fertilized soil and the unfertilized soil should be compared, and the fertilizer quality should be taken into consideration. When weighing the same soil mass, it is necessary to consider the changes in carbon sequestration effect caused by fertilizer differences. For example, if there are three soil samples of the same mass, one is unfertilized, one is fertilized with a small amount of low-concentration fertilizer, and one is fertilized with a large amount of high-concentration fertilizer, if the fertilizer quality is not considered and only the thermogravimetric analysis results are compared, the difference in mass loss between the soil samples may be mistakenly attributed to the properties of the soil itself, while ignoring the huge impact of different fertilizer qualities, and it is impossible to effectively compare the carbon sequestration effect of fertilized and unfertilized soils.

[0024] (IV) Place the soil sample in a thermogravimetric analyzer. The thermogravimetric analyzer is calibrated before testing. The calibration gas is high-purity nitrogen, and its flow rate is controlled at 20-30 ml / min (the flow rate can be selected as 200 ml / min, 250 ml / min, 300 ml / min, and any point in between). The thermogravimetric analysis process is set to heat up from room temperature to 900 °C at a heating rate of 10 °C / min, and the thermogravimetric analyzer is started to perform thermogravimetric analysis on the soil sample. During the heating process, the high-precision sensor of the thermogravimetric analyzer continuously records the mass change curve of the soil sample, and the soil sample M is obtained through the data acquisition system. 施肥 Quality change curve W t，施肥 and soil samples M 原始 Quality change curve W t，原始 , where t is temperature / °C. This heating rate can make the shape of the thermogravimetric curve more ideal, with a clear inflection point, which is convenient for observing and analyzing the mass changes of soil samples at different temperature stages.

[0025] (5) According to the mass change curve, two characteristic temperature ranges (300 - 600 °C, 600 - 900 °C) are determined. The basis for the selection of the characteristic temperature ranges is as follows: From room temperature to 300 °C, the mass loss is not calculated. This stage is mainly the volatilization of adsorbed water and a small amount of volatile substances in the soil. Their volatilization has no direct relation to the thermal decomposition process of carbonate - containing compounds and stable carbon - containing substances formed by fertilizers in the soil, and cannot reflect the carbon sequestration effect of fertilizers. The starting temperature and rate of volatilization of these volatile substances are affected by factors such as soil texture and pore structure, and it is difficult to accurately quantify their mass loss with a unified model or parameters. When the temperature is higher than 900 °C, other mineral components in the soil sample will start to undergo complex melting, phase change and other reactions not related to carbon sequestration, interfering with the judgment of the carbon sequestration effect of fertilizers. When determining the characteristic temperature ranges, the temperature error is controlled within ±10 °C to accurately capture the thermal decomposition stage of carbonate - containing compounds and stable carbon - containing substances; at the same time, when analyzing the mass change curve, the curve is smoothed and outliers are removed.

[0026] (1) In the temperature range of 300 - 600 °C, the carbonate - containing compounds in the soil sample undergo thermal decomposition. These carbonate - containing compounds are the reaction products of fertilizers and substances in the soil, including zinc carbonate (ZnCO3), magnesium carbonate (MgCO3), ammonium carbonate ((NH4)CO3), etc. Accurately calculate the mass loss rate Δm 施肥 of soil sample M 1，施肥 and the mass loss rate Δm 原始 of soil sample M 1，原始 . The calculation formula is as follows: Δm1=(M - M 300~600℃ ) / M×100%; In the formula, M is the initial mass of the soil sample, and M 300~600℃ is the mass of the soil sample at the end of the 300 - 600 °C range.

[0027] (2) In the temperature range of 600 - 900 °C, the stable carbon - containing substances formed after the soil sample adsorbs and absorbs carbon dioxide by fertilizers undergo thermal decomposition, including calcium carbonate (CaCO3), etc. Calculate the soil mass loss rate Δm 施肥 of soil sample M 2，施肥 and the soil mass loss rate Δm 原始 of soil sample M 2，原始 . The calculation formula is as follows: Δm2=(M 300~600℃ - M 600~900℃ ) / M×100%; In the formula, M 300~600℃ is the mass of the soil sample at the end of the 300 - 600 °C range, and M 600~900℃ is the mass of the soil sample at the end of the 600 - 900 °C range.

[0028] (6) Calculate the comprehensive carbon sequestration intensity index Z, and the calculation formula is as follows: Z = 0.4 * (Δm 1，施肥 - Δm 1，原始 ) + 0.6 * (Δm 2，施肥 - Δm 2，原始 ); In the formula, Z comprehensively considers the difference in mass loss between fertilized and unfertilized soils in different temperature ranges, and fully reflects the carbon sequestration efficiency of fertilizers. The larger Z is, the stronger the carbon sequestration ability is.

[0029] (7) Compare the parameter index Z of soil samples before and after fertilization to complete the evaluation of carbon sequestration effect. The specific criteria for the evaluation of carbon sequestration effect are as follows: (1) If 0% < Z ≤ 0.65%, it is considered that the fertilization treatment method is ineffective for carbon sequestration, indicating that the fertilizer fails to play an effective role in carbon sequestration in this soil environment.

[0030] (2) If the increase in the Z value of the soil after fertilization is less than the expected value compared with the Z value of the soil before fertilization and is close to the measurement error range, it needs to be measured 3 times repeatedly, and the average value is taken before evaluation. If the Z value of the soil sample after fertilization is significantly increased compared with the Z value of the soil sample before fertilization, it is considered that the fertilization treatment method is effective for carbon sequestration. The main basis for the evaluation of carbon sequestration effect in different acid-base soils is as follows: ①When the unfertilized soil is of the acidic soil type, the acidic soil has a relatively high hydrogen ion concentration. Hydrogen ions compete with the cations in the fertilizer (such as calcium, magnesium, iron, etc., which often participate in the formation of carbonate-containing compounds or stable carbon-containing structures during the carbon sequestration process) for adsorption sites, making it difficult for these key metal ions to effectively combine with carbonate, hindering the formation of carbonate-containing compounds, and thus affecting the reaction process between the fertilizer and carbon dioxide, reducing the initial carbon sequestration efficiency. For example, calcium ions should combine with carbonate to form calcium carbonate to fix carbon, but in an acidic environment, a large number of hydrogen ions are adsorbed on the soil particle surface first, inhibiting the formation of calcium carbonate. On the other hand, the chemical bonds of many carbonate-containing compounds and stable carbon-containing substances are less stable in an acidic environment and are more likely to break, promoting the premature release of carbon dioxide. For instance, the decomposition rate of magnesium carbonate in acidic soil is significantly faster than that in neutral or alkaline soil, resulting in a relatively small amount of fixed carbon retained in the soil due to the action of the fertilizer. Due to these chemical factors, the fertilizer has to overcome considerable difficulties to achieve carbon sequestration. Only when 0.65% < Z < 1.15%, the carbon sequestration effect is sufficient to offset the negative impact of the acidic environment, and it is determined that the carbon sequestration effect of this fertilization treatment method is significant; when 1.15% ≤ Z < 1.75%, it indicates that the carbon sequestration intensity is further enhanced, and the carbon sequestration effect of this fertilization treatment method is evaluated as relatively significant; when 1.75% ≤ Z ≤ 100%, it shows that the fertilizer exhibits extremely strong carbon sequestration ability in acidic soil, and the carbon sequestration effect of this fertilization treatment method is evaluated as very significant.

[0031] ②When the unfertilized soil is of the neutral soil type, the concentrations of hydrogen ions and hydroxide ions are moderate, providing an ideal chemical environment for fertilizer carbon sequestration. Under these conditions, the components in the fertilizer can react with carbon dioxide through normal chemical pathways, and the formation of carbonate-containing compounds and the formation of stable carbon-containing substances are not interfered by extreme acid-base conditions. At the same time, the original mineral components in the soil will not cause additional chemical reactions to consume fixed carbon due to acid-base imbalance, enabling the stable manifestation of the fertilizer carbon sequestration effect. Based on this stability, if 0.65% < Z < 1.25%, it indicates that the carbon sequestration effect of this fertilization treatment method is significant; when 1.25% ≤ Z < 1.85%, it shows that the carbon sequestration effect is further enhanced, and the carbon sequestration effect of this fertilization treatment method is evaluated as relatively significant; when 1.85% ≤ Z ≤ 100%, the carbon sequestration effect of this fertilization treatment method is evaluated as very significant.

[0032] ③When the unfertilized soil is of the alkaline soil type, the alkaline soil is rich in hydroxide ions. On the one hand, the hydroxide ions inhibit the rapid decomposition of carbon-containing substances, making the carbonate compounds formed by the fertilizer and the chemical bonds of stable carbon-containing substances more stable, capable of storing and fixing carbon for a long time. For example, the decomposition temperature of calcium carbonate increases in an alkaline environment and it is not easy to release carbon dioxide. On the other hand, the alkaline conditions stimulate the higher activity of some metal ions (such as calcium ions, magnesium ions, etc.), making it easier for them to combine with carbonate ions, accelerating the formation of carbonate compounds and enhancing the carbon sequestration efficiency. Based on this, the fertilizer is more likely to achieve carbon sequestration in alkaline soil. Even when the Z value is in the range of 0.65% - 1.05%, it is sufficient to overcome basic factors such as the natural carbon cycle of the soil and achieve a significant carbon sequestration effect. When 1.05% ≤ Z < 1.65%, the carbon sequestration effect is further enhanced to a relatively significant level. When 1.65% ≤ Z ≤ 100%, it indicates that the fertilizer exhibits a very significant carbon sequestration ability in alkaline soil.

[0033] Example 1: As Figure 1 shown, the present invention discloses a method for evaluating the carbon sequestration effect of a fertilizer, and the evaluation method includes the following steps.

[0034] (I) When collecting soil samples, select representative plots. In the fertilized area and the unfertilized area, the fertilizer used is commercial fertilizer 1. Use the multi-point sampling method to collect soil samples, and transfer the collected soil samples to sealed bags and make marks respectively to ensure that the samples truly reflect the soil characteristics of the selected area.

[0035] (i) When selecting representative plots, select plots with a pH value of 4.5 - 6.5, a soil texture mainly composed of clay or loam clay, and the planted crop being rice.

[0036] (ii) Use the multi-point sampling method to take samples. Divide the plot evenly into multiple square grid areas of the same size, and set the center position or the intersection of the diagonal of each grid area as the sampling point. After determining the sampling points, use a soil drill to collect soil at a depth of 15 cm. Vertically insert the soil drill at each sampling point, rotate it slowly and press it down to collect sufficient soil, and then put the soil collected from each sampling point into a sealed bag respectively, make marks, and indicate key information such as the sampling point location and the fertilization treatment situation.

[0037] (II) In the laboratory environment, use a high-precision grinder to grind the soil samples for 10 minutes to ensure that the particle size of the samples is uniformly less than 0.5 mm. At the same time, during the grinding process, clean the grinder intermittently to prevent cross-contamination of the soil samples.

[0038] (3) After grinding, transfer the soil sample to a constant temperature oven and dry it to the required drying procedure. The oven temperature is 45 °C and the drying time is controlled within 10 h. Weigh a certain mass of the soil sample. The soil sample after fertilization treatment is denoted as M 施肥 , and the soil sample without fertilization treatment is denoted as M 原始 .

[0039] (4) Place the soil sample in a thermogravimetric analyzer. The thermogravimetric analyzer is calibrated before the test. The calibration gas is high-purity nitrogen, and its flow rate is controlled at 25 ml / min. The thermogravimetric analysis process is set to heat from room temperature to 900 °C at a heating rate of 10 °C / min, and start the thermogravimetric analyzer to perform thermogravimetric analysis on the soil sample. During the heating process, the high-precision sensor of the thermogravimetric analyzer continuously records the mass change curve of the soil sample, and the mass change curve W 施肥 of the soil sample M t，施肥 and the mass change curve W 原始 of the soil sample M t，原始 are obtained, where t is the temperature / °C, and the mass loss is not calculated from room temperature to 300 °C.

[0040] (5) Based on the mass change curve, when determining the characteristic temperature range, the temperature error is controlled within ±10 °C; at the same time, when analyzing the mass change curve, the curve is smoothed and outliers are removed. Determine two characteristic temperature ranges (300 - 600 °C, 600 - 900 °C): (1) In the range of 300 - 600 °C, calculate the mass loss rate Δm 施肥 of the soil sample M 1，施肥 and the mass loss rate Δm 原始 of the soil sample M 1，原始 . The calculation formula is as follows: Δm1=(M - M 300~600℃ ) / M × 100%; In the formula, M is the initial mass of the soil sample, and M 300~600℃ is the mass of the soil sample at the end of the range of 300 - 600 °C. Specifically, M 施肥 = 1.126 g, M 原始 = 1.245 g, M 300~600℃，施肥 = 1.121 g, M 300~600℃，原始 = 1.241 g, Δm 1，施肥 = 0.44%, Δm 1，原始 = 0.32%.

[0041] (2) In the range of 600 - 900 °C, calculate the soil mass loss rate Δm 施肥 of the soil sample M 2，施肥 and the soil sample M 原始The soil mass loss rate Δm 2，原始 , and the calculation formula is as follows: Δm2=(M 300~600℃ -M 600~900℃ ) / M×100%; In the formula, M 300~600℃ is the mass of the soil sample at the end of the 300 - 600 °C interval, and M 600~900℃ is the mass of the soil sample at the end of the 600 - 900 °C interval. Specifically, M 300~600℃，施肥 = 1.121 g, M 300~600℃，原始 = 1.241 g, M 600~900℃，施肥 = 1.114 g, M 600~900℃，原始 = 1.237 g, Δm 2，施肥 = 0.62%, Δm 2，原始 = 0.32%.

[0042] (VI) Calculate the comprehensive carbon sequestration intensity index Z, and the calculation formula: Z = 0.4*(Δm 1，施肥 -Δm 1，原始 ) + 0.6*(Δm 2，施肥 -Δm 2，原始 ); After calculation, Z = 0.22%.

[0043] VII) Compare the parameter index Z of the soil samples before and after fertilization, and complete the evaluation of the carbon sequestration effect. Since 0% < Z ≤ 0.65%, it is considered that this fertilization treatment method is ineffective for carbon sequestration, indicating that the fertilizer fails to play an effective role in carbon sequestration in this soil environment.

[0044] Example 2: As Figure 1 shown, the present invention discloses a method for evaluating the carbon sequestration effect of fertilizers, and the evaluation method includes the following steps.

[0045] I) When collecting soil samples, select representative plots, and apply commercial fertilizer 2 in the fertilized area and the unfertilized area respectively; use a special soil sampling tool to collect soil by multi-point sampling method, and transfer the collected soil samples to sealed bags and make marks respectively to ensure that the samples taken truly reflect the soil characteristics of the selected area.

[0046] I) When selecting representative plots, select plots with a pH value of 4.5 - 6.5, mainly clay or loam clay soil texture, and the planted crop is rice.

[0047] (II) Sampling is carried out using the multi-point sampling method. The plot is evenly divided into multiple square grid areas of the same size, and the sampling points are set at the center position or the intersection of the diagonals of each grid area. After determining the sampling points, a soil drill is used to collect soil at a depth of 15 cm. The soil drill is vertically inserted into each sampling point, slowly rotated and pressed down to collect sufficient soil, and then the soil collected from each sampling point is separately put into a sealed bag, marked, and key information such as the location of the sampling point and the fertilization treatment situation to which it belongs is noted.

[0048] (2) Under laboratory conditions, a high-precision grinder is used to grind the soil sample for 10 minutes to ensure that the particle size of the sample is uniformly less than 0.5 mm. At the same time, during the grinding process, the grinder is intermittently cleaned to prevent cross-contamination of the soil samples.

[0049] (3) After grinding, the soil sample is transferred to a constant-temperature oven and dried to the required drying program. The oven temperature is 45 °C, and the drying time is controlled at 10 h. A certain mass of the soil sample is weighed. The soil sample after fertilization treatment is denoted as M 施肥 , and the soil sample without fertilization treatment is denoted as M 原始 .

[0050] (4) The soil sample is placed in a thermogravimetric analyzer. The thermogravimetric analyzer is calibrated before testing. The calibration gas is high-purity nitrogen, and its flow rate is controlled at 25 ml / min. The thermogravimetric analysis process is set to heat up from room temperature to 900 °C at a heating rate of 10 °C / min, and the thermogravimetric analyzer is started to conduct thermogravimetric analysis on the soil sample. During the heating process, the high-precision sensor of the thermogravimetric analyzer continuously records the mass change curve of the soil sample, and the mass change curve W 施肥 of the soil sample M t，施肥 and the mass change curve W 原始 of the soil sample M t，原始 are obtained, where t is the temperature / °C, and the mass loss is not calculated from room temperature to 300 °C.

[0051] (5) Based on the mass change curve, when determining the characteristic temperature range, the temperature error is controlled within the range of ±10 °C; at the same time, when analyzing the mass change curve, the curve is smoothed and outliers are removed. Two characteristic temperature ranges (300 - 600 °C, 600 - 900 °C) are determined: (1) Within the range of 300 - 600 °C, calculate the mass loss rate Δm 施肥 of the soil sample M 1，施肥 and the mass loss rate Δm 原始 of the soil sample M 1，原始 . The calculation formula is as follows: Δm1=(M - M 300~600℃ ) / M × 100%; Wherein, M is the initial mass of the soil sample, and M 300~600℃ is the mass of the soil sample at the end of the temperature range from 300 to 600 °C. Specifically, M 施肥 = 1.376 g, M 原始 = 1.227 g, M 300~600℃，施肥 = 1.365 g, M 300~600℃，原始 = 1.223 g, Δm 1，施肥 = 0.80%, Δm 1，原始 = 0.33%.

[0052] (2) In the temperature range from 600 to 900 °C, calculate the soil mass loss rate Δm 施肥 of the soil sample M 2，施肥 and the soil mass loss rate Δm 原始 of the soil sample M 2，原始 . The calculation formula is as follows: Δm2 = (M 300~600℃ - M 600~900℃ ) / M × 100%; Wherein, M 300~600℃ is the mass of the soil sample at the end of the temperature range from 300 to 600 °C, and M 600~900℃ is the mass of the soil sample at the end of the temperature range from 600 to 900 °C. Specifically, M 300~600℃，施肥 = 1.365 g, M 300~600℃，原始 = 1.223 g, M 600~900℃，施肥 = 1.343 g, M 600~900℃，原始 = 1.221 g, Δm 2，施肥 = 1.60%, Δm 2，原始 = 0.33%.

[0053] (VI) Calculate the comprehensive carbon sequestration intensity index Z. The calculation formula: Z = 0.4 * (Δm 1，施肥 - Δm 1，原始 ) + 0.6 * (Δm 2，施肥 - Δm 2，原始 ); After calculation, Z = 0.95%.

[0054] (VII) Compare the parameter index Z of the soil samples with and without fertilization to complete the evaluation of the carbon sequestration effect. Since when the soil without fertilization treatment is of acidic soil type and 0.65% < Z < 1.15%, it is determined that the fertilization treatment method has a significant carbon sequestration effect.

[0055] Example 3: As Figure 1 shown, the present invention discloses a method for evaluating the carbon sequestration effect of fertilizers. The evaluation method includes the following steps.

[0056] (1) When collecting soil samples, select representative plots. In the fertilized area and the unfertilized area respectively, the fertilizer applied is commercial fertilizer 3. Use a special soil sampling tool to collect soil by the multi-point sampling method. Transfer the collected soil samples to sealed bags and make marks to ensure that the samples truly reflect the soil characteristics of the selected areas.

[0057] (I) When selecting representative plots, choose plots with a pH value of 4.5 - 6.5, mainly clay or loam clay soil texture, and the planted crop is rice.

[0058] (II) Use the multi-point sampling method to take samples. Divide the plot evenly into multiple square grid areas of the same size, and set the center position or the intersection of the diagonal of each grid area as the sampling point. After determining the sampling points, use a soil drill to collect soil at a depth of 15 cm. Vertically insert the soil drill at each sampling point, rotate it slowly and press it down to collect sufficient soil, and then put the soil collected from each sampling point into a sealed bag respectively, make marks, and indicate key information such as the sampling point location and the fertilization treatment situation.

[0059] (2) In the laboratory environment, use a high-precision grinder to grind the soil samples for 10 min to ensure that the particle size of the samples is uniformly less than 0.5 mm. At the same time, during the grinding process, clean the grinder intermittently to prevent cross-contamination of the soil samples.

[0060] (3) After grinding, transfer the soil samples to a constant-temperature oven and dry them to the required drying procedure. The oven temperature is 45 °C, and the drying time is controlled at 10 h. Weigh a certain mass of soil samples. The soil samples after fertilization treatment are denoted as M 施肥 , and the soil samples without fertilization treatment are denoted as M 原始 .

[0061] (4) Place the soil samples in a thermogravimetric analyzer. The thermogravimetric analyzer is calibrated before testing. The calibration gas is high-purity nitrogen, and its flow rate is controlled at 25 ml / min. The thermogravimetric analysis process is set to heat from room temperature to 900 °C at a heating rate of 10 °C / min, and start the thermogravimetric analyzer to conduct thermogravimetric analysis on the soil samples. During the heating process, the high-precision sensor of the thermogravimetric analyzer continuously records the mass change curve of the soil samples, and obtains the mass change curve W 施肥 of soil sample M t，施肥 and the mass change curve W 原始 of soil sample M t，原始 , where t is the temperature / °C, and the mass loss is not calculated from room temperature to 300 °C.

[0062] (5) When determining the characteristic temperature range based on the mass change curve, the temperature error is controlled within ±10°C; at the same time, when analyzing the mass change curve, the curve is smoothed and outliers are removed. Two characteristic temperature ranges (300 - 600°C, 600 - 900°C) are determined: (1) In the range of 300 - 600°C, calculate the mass loss rate Δm 施肥 of the soil sample M 1，施肥 and the mass loss rate Δm 原始 of the soil sample M 1，原始 . The calculation formula is as follows: Δm1 = (M - M 300~600℃ ) / M × 100%; In the formula, M is the initial mass of the soil sample, and M 300~600℃ is the mass of the soil sample at the end of the 300 - 600°C range. Specifically, M 施肥 = 1.308g, M 原始 = 1.213g, M 300~600℃，施肥 = 1.299g, M 300~600℃，原始 = 1.209g, Δm 1，施肥 = 0.69%, Δm 1，原始 = 0.33%.

[0063] (2) In the range of 600 - 900°C, calculate the soil mass loss rate Δm 施肥 of the soil sample M 2，施肥 and the soil mass loss rate Δm 原始 of the soil sample M 2，原始 . The calculation formula is as follows: Δm2 = (M 300~600℃ - M 600~900℃ ) / M × 100%; In the formula, M 300~600℃ is the mass of the soil sample at the end of the 300 - 600°C range, and M 600~900℃ is the mass of the soil sample at the end of the 600 - 900°C range. Specifically, M 300~600℃，施肥 = 1.299g, M 300~600℃，原始 = 1.209g, M 600~900℃，施肥 = 1.270g, M 600~900℃，原始 = 1.205g, Δm 2，施肥 = 2.22%, Δm 2，原始 = 0.33%.

[0064] (6) Calculate the comprehensive carbon sequestration intensity index Z. The calculation formula: Z = 0.4 * (Δm 1，施肥 - Δm 1，原始 ) + 0.6 * (Δm 2，施肥 - Δm2，原始 ); After calculation, Z = 1.27% is obtained.

[0065] (7) Compare the parameter index Z of the soil samples before and after fertilization to complete the evaluation of the carbon sequestration effect. Since when the soil without fertilization treatment is of acidic soil type and 1.15% ≤ Z < 1.75%, it indicates that the fertilization treatment method has a relatively significant carbon sequestration effect.

[0066] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for evaluating the carbon sequestration effect of fertilizers, characterized in that, The evaluation method includes the following steps: Step 1: When collecting soil samples, select representative plots. In the fertilized area and the unfertilized area respectively, collect soil by the multi-point sampling method, and transfer the collected soil samples to sealed bags and make marks. Step 2: Under laboratory conditions, grind the soil samples until the particle size is less than 0.5 mm. Step 3: After grinding is completed, transfer the soil sample to a constant temperature oven and dry it to the required dryness; weigh a certain mass of the soil sample, and the soil sample after fertilization treatment is denoted as M 施肥 , and the soil sample without fertilization treatment is denoted as M 原始 ; Step 4: Place the soil sample in a thermogravimetric analyzer. The thermogravimetric analysis process of the thermogravimetric analyzer is set to heat from room temperature to 900 °C at a heating rate of 10 °C / min; start the thermogravimetric analyzer to perform thermogravimetric analysis on the soil sample. During the heating process, the sensor of the thermogravimetric analyzer continuously records the mass change curve of the soil sample, and the mass change curve W of the soil sample M is obtained through the data acquisition system 施肥 of the soil sample M t，施肥 and the mass change curve W 原始 of the soil sample M t，原始 , where t is the temperature / °C; Step 5: According to the mass change curve, determine two characteristic temperature ranges: (1) Thermally decompose the carbonate compounds in the soil sample in the temperature range of 300 - 600 °C, and calculate the mass loss rate Δm 施肥 of the soil sample M 1，施肥 and the mass loss rate Δm 原始 of the soil sample M 1，原始 The calculation formula is as follows: Δm1=(M - M 300~600℃ ) / M×100%; where M is the initial mass of the soil sample, and M 300~600℃ is the mass of the soil sample at the end of the 300 - 600 °C range; (2)Thermally decompose the stable carbon-containing substances formed after the fertilizer in the soil sample adsorbs and absorbs carbon dioxide in the range of 600-900 °C, and calculate the soil sample M in this range 施肥 of the soil mass loss rate Δm 2，施肥 and the soil sample M 原始 of the soil mass loss rate Δm 2，原始 , and the calculation formula is as follows: Δm2=(M 300~600℃ -M 600~900℃ ) / M×100%; Where M 300~600℃ is the mass of the soil sample at the end of the 300 - 600 °C range, and M 600~900℃ is the mass of the soil sample at the end of the 600 - 900 °C range; Step 6: Calculate the comprehensive carbon sequestration intensity index Z, and the calculation formula is as follows: Z = 0.4 * (Δm 1，施肥 - Δm 1，原始 ) + 0.6 * (Δm 2，施肥 - Δm 2，原始 ); Step 7: Compare the parameter index Z of the soil samples with and without fertilization to complete the evaluation of the carbon sequestration effect.

2. The evaluation method for the carbon sequestration effect of fertilizers according to claim 1, wherein, When selecting representative plots in Step 1, select them by comprehensively considering the following various factors: (1) Agricultural planting area: For studying the carbon sequestration of food crop soils by fertilization, select farmlands with typical planting patterns, that is, plots with single planting varieties, uniform planting densities, and conventional farming operations. (2) Acidic soil: Select plots with a pH value of 4.5 - 6.5, clay or loam clay texture, acid-tolerant vegetation, and a slope of less than 5°. (3) Natural ecological area: For forest soil research, select mature forest areas with a forest canopy closure of 0.6 - 0.8, rich understory vegetation, distinct soil horizons, and a moderate humus layer.

3. The evaluation method for the carbon sequestration effect of fertilizers according to claim 1, characterized in that The specific operation of the multi-point sampling method in Step 1 is as follows: (1) Divide the plot evenly into several square or rectangular grid areas of the same size, and set the sampling points at the center position or the intersection of the diagonals of each grid area. (2) After determining the sampling points, use a special soil sampling tool to collect soil at a depth of 0 - 30 cm. Vertically insert the special soil sampling tool at each sampling point, slowly rotate and press down to collect sufficient soil, then put the soil collected from each sampling point into a sealed bag respectively, make marks, and indicate the sampling point position and the information of the fertilization treatment situation.

4. The evaluation method for the carbon sequestration effect of fertilizers according to claim 1, wherein When grinding the soil samples with a grinder in Step 2, control the grinding time within 10 - 15 min, and clean the grinder intermittently during the grinding process.

5. The evaluation method for the carbon sequestration effect of fertilizers according to claim 1, characterized in that, In Step 3, the oven temperature is 40 - 50 °C, and the drying time is controlled within 8 - 12 h.

6. The evaluation method for the carbon sequestration effect of fertilizers according to claim 1, wherein In Step 4, calibrate the thermogravimetric analyzer before testing. The calibration gas is high-purity nitrogen, and its flow rate is controlled within 20 - 30 ml / min.

7. The evaluation method for the carbon sequestration effect of fertilizers according to claim 1, characterized in that, When determining the characteristic temperature range in Step 5, control the temperature error within the range of ±10 °C, and at the same time perform smoothing processing and outlier rejection on the mass change curve.

8. The evaluation method for the carbon sequestration effect of fertilizers according to claim 1, wherein The specific criteria for evaluating the carbon sequestration effect in Step 7 are as follows: (1) If 0% < Z ≤ 0.65%, it is considered that the fertilization treatment method is ineffective for carbon sequestration, indicating that the fertilizer fails to play an effective carbon sequestration role in this soil environment. (2) If the Z value of the soil sample after fertilization treatment is significantly increased compared with the Z value of the soil sample without fertilization treatment, it is considered that the fertilization treatment method is effective for carbon sequestration, and: ① When the soil without fertilization treatment is of acidic soil type, if 0.65% < Z < 1.15%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is significant; if 1.15% ≤ Z < 1.75%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is relatively significant; if 1.75% ≤ Z ≤ 100%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is very significant. ② When the soil without fertilization treatment is of neutral soil type, if 0.65% < Z < 1.25%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is significant; if 1.25% ≤ Z < 1.85%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is relatively significant; if 1.85% ≤ Z ≤ 100%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is very significant. ③ When the soil without fertilization treatment is of alkaline soil type, if 0.65% < Z < 1.05%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is significant; if 1.05% ≤ Z < 1.65%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is relatively significant; if 1.65% ≤ Z ≤ 100%, it is evaluated that the carbon sequestration effect of this fertilization treatment method is very significant.

9. The evaluation method for the carbon sequestration effect of fertilizers according to claim 8, characterized in that When evaluating the carbon sequestration effect in step 7, if the increase range of the soil Z value after fertilization treatment compared to the soil Z value before fertilization treatment is less than the expected value and close to the measurement error range, it is necessary to repeat the measurement 3 times, take the average value and then conduct the evaluation.

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