Methods for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements

Abstract

This invention provides a method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements, belonging to the field of agricultural fertilization technology. Based on the soil's baseline carbon and target nitrogen requirement, this invention calculates and applies initial manure to activate microbial activity using a preset carbon-nitrogen ratio. It monitors soil biophysical signals in real time and compares them with high-efficiency carbon sequestration signals. When the matching degree is lower than a first threshold, a window period is entered. If the matching degree further falls below a second threshold during the window period, a second manure is immediately applied based on the decline duration and the average matching degree. When the matching degree recovers after a preset interval following the topdressing or naturally rises above a third threshold, the window period ends. Based on the sum of all topdressing amounts in this cycle, the amount of base fertilizer for the next cycle is adjusted. Finally, before the critical nitrogen requirement period, by measuring the soil's available nitrogen and deducting the expected nitrogen supply contribution from previous topdressing, a third final fertilizer is accurately calculated and supplemented to ensure sufficient nitrogen supply during the yield formation period.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilization methods, specifically a method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements. Background Technology

[0002] In the field of sustainable agricultural development, how to synergistically improve soil carbon sequestration capacity and crop nutrient utilization efficiency is an important issue. Conservation tillage techniques with straw mulching as the core, such as the Lishu model, have been proven to be effective in increasing carbon and enriching soil, but their effect on improving soil fertility has a saturation point and the process is relatively slow. At the same time, the large amount of livestock and poultry manure produced by the livestock industry is an important organic resource, and its application in the field has great potential in supplementing soil nutrients and promoting straw decomposition. However, there is a lack of scientific basis on how to use it and how much to use it. Blind or excessive application can easily lead to nutrient loss and environmental risks. Therefore, exploring a precision fertilization method that can dynamically couple the soil carbon sequestration process with the supply of manure nutrients is of great practical significance for simultaneously achieving soil health conservation and high and stable crop yields.

[0003] Currently, existing technologies mainly attempt to solve the above problems through two paths: one is the static recommendation fertilization method based on soil chemical testing and crop fertilizer requirement models. This method usually determines the application amount of chemical fertilizer and organic fertilizer once before sowing based on the basic soil fertility and target yield; the other is topdressing management based on a fixed agricultural calendar, that is, topdressing is carried out at certain preset stages of crop growth; in addition, some studies have focused on the macroscopic effects of the combined application of organic and inorganic fertilizers in long-term field trials. These methods all rely on pre-set, static empirical models or fixed time sequences, treating fertilization as a response to the static needs of soil and crops.

[0004] However, existing technologies suffer from a fundamental deficiency: they cannot perceive and respond in real time to the key biological processes within the soil ecosystem, namely the dynamic activity window of soil microorganisms driving straw decomposition and carbon sequestration. Due to the lack of ability to identify this dynamic biological window, current fertilization decisions are out of sync with it, failing to apply manure resources at the critical moment when microbial activity is at its peak and nutrient demand is most urgent. This significantly limits the efficiency of manure in promoting carbon sequestration and the humification conversion rate of straw. Simultaneously, existing technologies cannot reverse-engineer and optimize the initial fertilization strategy for the next production cycle based on the actual biological response of the soil to management measures in the current season. This results in rigid fertilization plans that are difficult to adapt to differences in basic soil fertility between plots and years. Furthermore, when balancing nutrients in the later stages of crop growth, existing methods struggle to accurately quantify the continued nitrogen supply from applied organic fertilizers in subsequent stages, easily leading to blind final fertilization and resulting in nutrient redundancy or insufficiency. These shortcomings collectively lead to low synergistic efficiency and imprecise resource utilization in existing fertilization models for promoting carbon sequestration and ensuring nitrogen supply.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements, comprising the following steps:

[0009] Step 1: After completing the straw return operation of the previous crop, before sowing the current crop, based on the soil background organic carbon content and the total nitrogen requirement corresponding to the target yield, calculate and apply the initial amount of manure fertilizer by activating the target through the preset carbon-nitrogen ratio.

[0010] Step 2: In the early stage of crop growth during the current cultivation cycle, continuously collect biophysical signals in the soil that characterize the intensity of microbial carbon fixation metabolism. Calculate the matching degree between the real-time data stream of the acquired biophysical signals and the high-efficiency carbon fixation metabolism signals. When the matching degree is lower than the first threshold, determine that the soil has entered the window period of high-efficiency carbon fixation metabolism and execute the topdressing decision in Step 3.

[0011] Step 3: Continuously monitor the matching degree during the window period until it falls below the second threshold for the first time during the window period. Calculate and apply the second manure topdressing amount based on the duration of the window period and the matching degree. If the amount of the second manure topdressing applied or the matching degree is higher than the third threshold during the window period, it is determined that the window period has ended. Based on the sum of the amount of the second manure topdressing in all window periods, the initial manure application amount for the next cultivation cycle is adjusted.

[0012] Step 4: Before the crop enters its critical nitrogen-requiring period in the current cultivation cycle, measure the available nitrogen content in the topsoil. Compare this measured value with the total amount of nitrogen that the crop needs to absorb from the critical nitrogen-requiring period until maturity. Based on the comparison results and the actual implementation of the topdressing decision, determine the final amount of the third final fertilizer to be applied quickly in the form of chemical fertilizer, and complete the fertilization to ensure the final yield of the current cultivation cycle.

[0013] Furthermore, the initial amount of manure to be applied is calculated based on the soil's background organic carbon content and the total nitrogen requirement corresponding to the target yield. The specific procedure is as follows:

[0014] After completing the straw return operation of the previous crop, before sowing the crop in the current cultivation cycle, soil samples of the topsoil are collected and tested to obtain the background organic carbon content of the soil, set the target yield for the current cultivation cycle, and calculate the total nitrogen requirement by combining the nitrogen absorption parameters required for the crop variety to achieve a unit yield in the current cultivation cycle.

[0015] The initial manure application rate is calculated with the goal of simultaneously satisfying the following two conditions: Condition 1 is that the ratio of total organic carbon to total available nitrogen contained in the soil background organic carbon, straw returned to the field and initial manure is within a preset carbon-nitrogen ratio range that can stimulate the initial activity of soil microorganisms; Condition 2 is that the amount of nitrogen supplied by the initial manure accounts for a preset ratio range of the total nitrogen demand.

[0016] Furthermore, the matching degree of the acquired real-time biophysical signal data stream is calculated with the efficient carbon fixation metabolism signal. The specific operation is as follows:

[0017] In-situ monitoring nodes are set up in the field to synchronously and continuously collect signal data on the carbon dioxide release rate, soil redox potential and soil temperature in the soil at a set frequency, forming a real-time data stream of biophysical signals.

[0018] The efficient carbon fixation metabolism signal is obtained in advance by means of the following method: During the historical cultivation cycle, the efficient carbon fixation metabolism stage in which the soil carbon fixation efficiency of soil microorganisms is consistently higher than the preset level is identified. Typical change sequences of carbon dioxide release rate, soil redox potential and soil temperature obtained by synchronous monitoring during this stage are extracted and used as ideal carbon dioxide release rate reference sequence, ideal soil redox potential reference sequence and ideal soil temperature reference sequence, respectively, to constitute the efficient carbon fixation metabolism signal.

[0019] The matching degree is obtained by calculating the comprehensive morphological similarity between real-time biophysical signal data streams and efficient carbon fixation metabolism signals. The formula is: ,in, The expression for comprehensive morphological similarity is: ,in This represents the dynamic time warp distance between the time series of carbon dioxide emission rates in the real-time data stream and the corresponding ideal carbon dioxide emission rate reference series. This represents the dynamic time-warped distance between the soil redox potential time series in the real-time data stream and the corresponding ideal soil redox potential reference series. This represents the dynamic time-warped distance between the soil temperature time series in the real-time data stream and the corresponding ideal soil temperature reference series. respectively to give The weighting coefficients, and .

[0020] Furthermore, the start and end of the window period for efficient carbon fixation metabolism are determined according to the following rules: a first threshold is set. Second threshold With the third threshold And satisfy When the matching score is higher than Drop to below When this window of efficient carbon fixation metabolism begins, a decision to apply topdressing fertilizer during this window is triggered.

[0021] During this window period, the matching degree is continuously monitored; the self-matching degree is lower than... From to its lower Stop, calculate the average of all matching degree values ​​during this decline process, and record it as the average decline in matching degree. Record the duration of this descent process, denoted as the window period descent duration. That is, within this window period, the matching degree changes from lower than From to below The duration of the stop;

[0022] The soil is considered to have left the current window of efficient carbon sequestration when any of the following conditions are met: Condition 1 is when the matching degree value is lower than... And complete the calculation and application of the second topdressing of manure; condition two is that within the window period, the matching degree value naturally rises to a level higher than After the window period ends, if the reason for the end is condition one, a fertilization response interval of a preset duration will be entered, during which the determination of the start of a new window period for efficient carbon fixation metabolism will be suspended; if the reason for the end is condition two, the determination of the start of a new window period for efficient carbon fixation metabolism will be resumed immediately.

[0023] Repeat the above operations during the early growth stage of the crop in the current cultivation cycle to identify multiple windows of efficient carbon fixation metabolism.

[0024] The specific method for calculating the amount of the second topdressing of manure is determined by the following formula:

[0025]

[0026] in, This refers to the amount of the second manure topdressing calculated when the topdressing decision is triggered during the i-th window period. This is the initial amount of manure applied. Let be the average of all matching scores within the descent duration of the i-th window period. The first threshold, For the duration of the descent during the i-th window period, This represents the expected typical duration based on crop variety and local climate conditions. and The adjustment coefficient is , and satisfies . .

[0027] Furthermore, the method for adjusting the initial application rate for the next cultivation cycle is defined by the following formula: Calculate the sum of the second manure topdressing amounts corresponding to all window periods within the current cultivation cycle, denoted as... Calculate the arithmetic mean of the decline durations corresponding to all windows within the current cultivation cycle, and denot it as the average decline duration. ;

[0028] The formula for adjusting the initial application rate for the next cultivation cycle is as follows:

[0029]

[0030] in, This indicates the initial amount of manure to be applied after adjusting for the next season's cultivation cycle. This refers to the total number of growing days in the current cultivation cycle from sowing to the critical nitrogen-required period. Learning rate coefficient for soil basic nitrogen supply capacity;

[0031] The method for dynamically calculating the amount of the second manure topdressing also includes an ecological safety constraint step: pre-setting a maximum topdressing limit based on the soil's environmental carrying capacity. For any given window period, if the amount of the second manure topdressing calculated according to the formula is greater than... The amount of the second top dressing of manure finally implemented during this window period shall be adopted. value.

[0032] Furthermore, details of each second topdressing application event actually triggered within each efficient carbon sequestration metabolism window are obtained and recorded, including the amount of manure applied each time and its corresponding specific date. For each application event, based on the total nitrogen content of the batch of manure, the duration from the fertilization date to the critical nitrogen requirement period, and the average temperature during this period, the effective nitrogen amount that the manure applied in this application event is expected to release before the critical nitrogen requirement period is estimated using a mineralization model, which is used as the single effective nitrogen supply.

[0033] The cumulative effective nitrogen supply is obtained by summing up the single effective nitrogen supply corresponding to all such application events within the current cultivation cycle. Finally, the measured available nitrogen content in the topsoil and this cumulative effective nitrogen supply are considered as the total effective nitrogen supply in the soil. This is then deducted from the total nitrogen required by the crop from the critical period of nitrogen demand until maturity. The resulting net nitrogen requirement difference is the amount of the third final fertilizer application that needs to be quickly supplemented in the form of chemical fertilizer. If there is no difference or the result is negative, then no chemical fertilizer is needed, and the amount of the third final fertilizer application is 0.

[0034] Furthermore, after completing a full cultivation cycle, the numerical sequence of actual matching degree obtained during the current cultivation cycle, the actual duration of the window period, the actual amount of fertilizer applied, and the final yield data are entered into the database. Then, using regression analysis, the accumulated data is analyzed... , , , , and Perform periodic calibration and optimization.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] This invention achieves accurate and objective determination of the window period for efficient carbon fixation metabolism of soil microorganisms by continuously collecting biophysical signals and calculating the matching degree with pre-stored high-efficiency carbon fixation characteristic spectra in real time. This technical feature allows fertilization decisions to break free from the constraints of fixed agricultural calendars and capture the key biological moments when straw decomposition and carbon fixation are most active in the soil. Furthermore, based on the real-time matching degree value and the duration of the window period, topdressing is dynamically calculated and applied immediately, ensuring that the input of manure nutrients is highly synchronized with the maximum demand of microorganisms in terms of timing and amount. This significantly improves the efficiency of manure in promoting straw humification and the rate of soil carbon fixation, achieving the first precise coupling of carbon fixation and nitrogen supply at the biological process level.

[0037] This invention assesses the soil's basic nitrogen supply capacity based on window period triggering characteristics and actual topdressing demand, and then reverses the initial manure application amount for the next cycle. This technical feature endows the system with self-learning and adaptive optimization capabilities across cultivation cycles. It can dynamically adjust the initial strategy based on the field's real biological feedback on management measures, thereby overcoming the shortcomings of existing static fertilization models that cannot adapt to specific plots and inter-year differences in soil fertility. This allows the fertilization plan to become more and more accurate with use, continuously approaching the optimal level.

[0038] This invention measures the available nitrogen content in the soil during critical periods and explicitly deducts the expected mineralized nitrogen supply from the applied topdressing in subsequent stages when calculating the final fertilizer supplementation amount. It incorporates the dynamic fertilization results based on biological response in the early stage into the final nutrient balance accounting, thus achieving precise identification and supplementation of nitrogen requirements during the crop yield formation period. This avoids excessive or insufficient fertilizer application due to neglecting the aftereffects of organic fertilizer, thereby maximizing the utilization efficiency of organic nutrients and reducing environmental risks while ensuring high crop yields. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall method flow of the present invention;

[0040] Figure 2 This is a fitting curve of the depth of decrease in matching degree of the present invention versus the ratio of topdressing amount to base fertilizer amount;

[0041] Figure 3 This is a curve showing the ratio of descent time to the ratio of topdressing amount to base fertilizer amount in this invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0043] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0044] Example:

[0045] Please see Figures 1-3 The present invention provides a technical solution:

[0046] A method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements, comprising the following steps:

[0047] Step 1: After completing the straw return operation of the previous crop, before sowing the current crop, based on the soil background organic carbon content and the total nitrogen requirement corresponding to the target yield, calculate and apply the initial amount of manure fertilizer by activating the target through the preset carbon-nitrogen ratio.

[0048] In a specific implementation, the purpose of this step is to establish a scientific and precise starting point for fertilization management in the current cultivation cycle. The core of this step is to calculate the initial amount of manure based on soil conditions and crop production goals through a set of clear quantitative criteria, which can effectively activate the carbon sequestration function of soil microorganisms and reliably ensure the nitrogen supply in the early stage of crop growth.

[0049] The initial amount of manure to be applied is calculated based on the soil's background organic carbon content and the total nitrogen requirement corresponding to the target yield. The specific procedure is as follows:

[0050] After completing the straw return operation of the previous crop, before sowing the crop in the current cultivation cycle, soil samples of the topsoil are collected and tested to obtain the background organic carbon content of the soil, set the target yield for the current cultivation cycle, and calculate the total nitrogen requirement by combining the nitrogen absorption parameters required for the crop variety to achieve a unit yield in the current cultivation cycle.

[0051] The current cultivation cycle refers to the complete agricultural production period from the sowing of the current crop to the harvest of the current crop. Its start and end dates are determined by the type of crop planted and local climate conditions. The target yield specifically refers to the total yield expected to be harvested in the current season from the field where this invention is planned to be implemented. The target yield is not arbitrarily set, but is determined based on a comprehensive assessment of the following three aspects: the historical yield level of the target field, the results of basic soil fertility tests, and the yield potential of the selected variety. The historical yield level of the field refers to the average actual yield of the target field over the past three to five years. The results of basic soil fertility tests, combined with the measured background organic carbon and available nitrogen content of the soil, assess the potential productivity of the soil. The yield potential of the selected variety is based on the average yield or high-yield record of the variety in regional trials provided by the seed supplier. For example, if the average corn yield of a field over the past three years is 600 kg per mu, the soil fertility test shows that the fertility is moderate, and a new variety with a yield increase potential of about 10% is selected in the current year, and the climate forecast is normal, then the target yield for the current season will be set at about 660 kg per mu.

[0052] Background organic carbon content in soil refers to the mass fraction of carbon in the organic matter inherent in the topsoil before the application of seasonal organic materials (straw and planned manure). It is determined by collecting mixed soil samples from the 0-20 cm topsoil layer and using the potassium dichromate oxidation-external heating method. Pre-sowing available nitrogen content in soil refers to the total amount of nitrogen forms (mainly ammonium nitrogen and nitrate nitrogen) in the topsoil that can be directly absorbed and utilized by crop roots at the moment before sowing. It is generally characterized by alkaline-available nitrogen content, which is measured using the alkaline diffusion method on soil samples collected before sowing. The nitrogen requirement per unit yield parameter for crops refers to the number of kilograms of nitrogen that a specific crop variety needs to absorb from the environment to produce 100 kg of economic yield (such as grain). This is a relatively stable parameter determined by the genetic characteristics of the crop variety.

[0053] The calculation of carbon and nitrogen inputs for straw returned to the field includes: estimation of straw dry matter mass, which is estimated based on the actual yield of the previous crop and the grain-to-straw ratio (the ratio of economic yield to straw dry weight, 1:1.2 to 1:1.5 for corn). For example, if the previous corn yield was 600 kg / mu and the grain-to-straw ratio was 1:1.3, then the dry matter mass of straw returned to the field would be approximately 780 kg / mu; calculation of straw carbon content, as the organic carbon content in crop straw is relatively stable, and is generally estimated as 40% of its dry matter mass, therefore, straw carbon content equals straw dry matter mass multiplied by 0.4; and calculation of straw nitrogen content, as the nitrogen content of straw needs to be obtained through laboratory testing. The value can be obtained by referring to publicly available data. For example, the nitrogen content of corn stalks is about 0.6 percent (dry basis). Therefore, the nitrogen content of stalks is equal to the dry weight of stalks multiplied by 0.006. The carbon and nitrogen content parameters of manure refer to the percentage of organic carbon and total nitrogen in the planned application of livestock and poultry manure (such as pig manure and cow manure) in terms of wet or dry weight. The method of obtaining the data is to sample the batch of manure to be applied and send it to the laboratory for analysis. The organic carbon content is determined by the potassium dichromate oxidation method, and the total nitrogen content is determined by the Kjeldahl method. If commercial organic fertilizer is used, the nutrient content indicated on its product certificate can be directly referred to.

[0054] After the previous crop straw return to the field is completed and before sowing in the current cultivation cycle, standardized field sampling and laboratory analysis are required. The specific operation is as follows: In the target field, according to the standard method of agricultural soil sampling, a mixed sample of topsoil is collected and sent to the laboratory for testing. Two key data are obtained through standard measurement methods: one is the soil background organic carbon content, which represents the soil's inherent persistent carbon pool level; the other is the available nitrogen content of the topsoil before sowing, which represents the mineral nitrogen base that can be directly used by the crop at the time of sowing. At the same time, the target yield for this cultivation cycle is determined according to the production plan, and the total nitrogen requirement required to achieve the target yield is calculated based on the recognized nitrogen requirement per unit yield parameter of the selected crop variety. These data together constitute the input basis for subsequent calculations.

[0055] In practice, it is necessary to collect mixed soil samples from the topsoil layer (0-20 cm) in the planned planting area according to standard soil sampling specifications, such as using an S-shaped or quincunx pattern sampling method. These samples should be sent to a professional laboratory to determine the background organic carbon content of the soil, which is determined using the potassium dichromate external heating method, and the available nitrogen content of the soil before sowing, which is determined using the alkaline hydrolysis diffusion method. These two data represent the size of the relatively stable carbon pool in the soil and the level of readily available nitrogen that crops can directly utilize, respectively, and are the basis for calculation. At the same time, based on local production conditions and variety characteristics, the target yield for the current cultivation cycle should be determined, and the nitrogen requirement per unit yield of the crop variety should be looked up.

[0056] The initial manure application rate is calculated with the goal of simultaneously satisfying the following two conditions: Condition 1 is that the ratio of total organic carbon to total available nitrogen contained in the soil background organic carbon, straw returned to the field and initial manure is within a preset carbon-nitrogen ratio range that can stimulate the initial activity of soil microorganisms; Condition 2 is that the amount of nitrogen supplied by the initial manure accounts for a preset ratio range of the total nitrogen demand.

[0057] Two core preset parameter criteria are defined and applied for modeling calculations. These two criteria are the bridge between agronomic principles and executable mathematical models. First, they provide the optimal starting energy for soil microbial communities to quickly activate their functions of decomposing and fixing carbon in straw returned to the field. Second, on this basis, they provide a reasonable basic nitrogen supply for crop seedling growth and avoid nutrient loss or seedling overgrowth risks caused by excessive fertilization.

[0058] Regarding the first criterion, even if the ratio of total carbon to total nitrogen in the soil's background organic carbon, returned straw, and initial manure is within a preset carbon-nitrogen ratio range that can stimulate the initial activity of soil microorganisms, this range has a clear scientific basis and operational definition. The rationale for this setting stems from the basic principles of soil microbial ecology: when microorganisms decompose organic matter, they need to maintain an appropriate carbon-nitrogen ratio for their cell growth; when the overall carbon-nitrogen ratio of exogenous organic materials is too high, microorganisms will fix a large amount of nitrogen in the soil to meet their own growth needs, leading to competition with crops for nitrogen; when the carbon-nitrogen ratio is too low, nitrogen is easily lost in gaseous form; numerous studies and agricultural practices have proven that controlling the carbon-nitrogen ratio of mixed organic matter within the range of 20:1 to 25:1 is most conducive to initiating and maintaining a vigorous and efficient microbial decomposition and metabolism process, thereby accelerating straw decomposition and initiating soil carbon sequestration;

[0059] In terms of operation, the preset range refers to the ratio range of 20:1 to 25:1 mentioned above. When calculating, the total carbon content is obtained by adding the soil organic carbon content, the carbon content of straw returned to the field, and the carbon content of the initial manure to be determined. The total effective nitrogen content is obtained by adding the soil available nitrogen content, the nitrogen content of straw returned to the field, and the nitrogen content of the initial manure to be determined. The ratio of the total carbon content to the total effective nitrogen content is required to fall between 20 and 25. This constitutes the first mathematical constraint for solving the initial manure application amount.

[0060] The carbon-to-nitrogen ratio range (20:1 to 25:1) is established based on classic studies in soil microbial ecology. The carbon-to-nitrogen ratio of microbial somatic cells is approximately 8:1 to 12:1, but they require additional carbon as an energy source when decomposing organic matter. Therefore, the optimal carbon-to-nitrogen ratio for substrate decomposition is between 20:1 and 30:1. This invention selects a narrower range of 20:1 to 25:1 to more actively stimulate microbial activity, while avoiding excessively strong microbial nitrogen fixation (competing with crops for nitrogen) due to an excessively high carbon-to-nitrogen ratio (greater than 30), or excessively low carbon-to-nitrogen ratio (less than 20) leading to rapid nitrogen loss.

[0061] Regarding the second criterion, even if the amount of nitrogen supplied by the initial manure reaches a preset ratio range relative to the total nitrogen requirement, this range is set by comprehensively considering the balance and safety of the nutrient supply strategy. The reason for this setting is that one of the main functions of the initial manure is to provide the nitrogen base for the early stage of crop growth, but it should not meet the needs of the entire growth period at once. This is because the nitrogen release from manure is slow and the utilization rate in the current season is uncertain, and excessive basal application poses a risk of leaching. At the same time, it is also necessary to reserve room for adjustment for subsequent dynamic topdressing based on the soil carbon sequestration metabolism. This preset ratio range is generally set between 30% and 50%. In specific applications, it is fine-tuned according to the soil fertility level of the field. For fields with poor basic soil fertility, the upper limit of this range is used, and for fertile fields, the lower limit is used. The mathematical expression of this criterion is that the total nitrogen amount obtained by multiplying the amount of initial manure application by its total nitrogen content, divided by the total nitrogen requirement of the crop calculated in the previous steps, should be in the range of 0.3 to 0.5. This constitutes the second mathematical constraint for solving the initial manure application amount.

[0062] The range of nitrogen supply from basal fertilizer (30% to 50%) is set by combining the law of diminishing returns of fertilizer and the principle of comprehensive nutrient resource management. If all the required nitrogen is applied at once, its utilization rate will be significantly reduced and environmental risks will be increased. Controlling the nitrogen supply from basal fertilizer to 30%-50% of the total demand throughout the growth period can not only provide necessary protection for the early growth of crops, but also reserve sufficient decision-making space for subsequent precise regulation based on crop growth and soil conditions (dynamic topdressing and final fertilizer supplementation). It is the key design for achieving precise regulation throughout the entire process.

[0063] Finally, comprehensive calculations and field application are performed. By combining the two inequality constraints mentioned above and substituting all known and set parameters, including soil carbon and nitrogen content, straw carbon and nitrogen content, manure carbon and nitrogen content, total crop nitrogen requirement, and specific values ​​within two preset ranges, a unique initial manure application rate that satisfies all conditions can be obtained. This calculation is completed iteratively using a simple mathematical model and computational tools. The calculated initial manure application rate is the recommended value. Subsequently, before sowing, it is applied to the soil tillage layer and mixed evenly using conventional fertilization machinery, thus completing all operations.

[0064] Step 2: In the early stage of crop growth during the current cultivation cycle, continuously collect biophysical signals in the soil that characterize the intensity of microbial carbon fixation metabolism. Calculate the matching degree between the real-time data stream of the acquired biophysical signals and the high-efficiency carbon fixation metabolism signals. When the matching degree is lower than the first threshold, determine that the soil has entered the window period of high-efficiency carbon fixation metabolism and execute the topdressing decision in Step 3.

[0065] In a specific implementation, this step aims to monitor and quantify the intensity of soil microbial carbon fixation metabolism in real time, and accurately identify the critical period when carbon fixation efficiency shifts from a high-efficiency state to a decline, thus requiring external nutrient input for intervention, namely the window period of high-efficiency carbon fixation metabolism. This step achieves state perception and turning point judgment of abstract biological processes by quantitatively comparing multiple online monitored physical signals with a pre-stored high-efficiency state template.

[0066] The matching degree between the acquired real-time biophysical signal data stream and the efficient carbon fixation metabolism signal is calculated. The specific operation is as follows:

[0067] In-situ monitoring nodes are set up in the field to synchronously and continuously collect signal data on the carbon dioxide release rate, soil redox potential and soil temperature in the soil at a set frequency, forming a real-time data stream of biophysical signals.

[0068] Within the fields where this method is implemented, at least three monitoring points representative of the overall condition are selected based on the field's shape and area. At each point, an integrated sensor array is vertically installed in the soil at a depth of five to ten centimeters below the surface. This depth represents the boundary between the straw mulch layer and the mineral soil, where microbial activity is most active. The collected signals include soil carbon dioxide release rate, soil redox potential, and soil temperature. The soil carbon dioxide release rate is measured using a soil respiration chamber or a solid carbon dioxide sensor, directly reflecting the intensity of microbial respiration and total carbon metabolism. The sampling frequency is set to once per hour. The soil redox potential is measured using... The soil redox state and related microbial metabolic processes, such as nitrification, denitrification, and iron-manganese reduction, are measured using platinum electrodes and a reference electrode. The data acquisition frequency is set to once per hour. Soil temperature is measured using a digital temperature sensor, which is a key environmental factor regulating the activity of all microbial enzymes. The data acquisition frequency is set to once per hour. The measurement data from each node are transmitted in real time to the central data processing unit via a wireless transmission network. After the unit performs time synchronization alignment and quality checks (removing obvious outliers), it forms three continuous data sequences that strictly correspond to the timestamps, which are the real-time data streams of the biophysical signals.

[0069] The efficient carbon fixation metabolism signal is obtained in advance by means of the following method: During the historical cultivation cycle, the efficient carbon fixation metabolism stage in which the soil carbon fixation efficiency of soil microorganisms is consistently higher than the preset level is identified. Typical change sequences of carbon dioxide release rate, soil redox potential and soil temperature obtained by synchronous monitoring during this stage are extracted and used as ideal carbon dioxide release rate reference sequence, ideal soil redox potential reference sequence and ideal soil temperature reference sequence, respectively, to constitute the efficient carbon fixation metabolism signal.

[0070] Historical cultivation cycles were selected from the past three to five cycles with complete meteorological and agricultural records, showing good performance in both final crop yield and soil organic carbon. During these historical cycles, soil carbon dioxide release rate, soil redox potential, and soil temperature were simultaneously and continuously monitored using the same equipment and methods as described above during the early crop growth stage (from sowing to jointing). To accurately identify the efficient carbon sequestration stage, dedicated observation plots were established within the historical cycles, and soil carbon sequestration efficiency was measured using the following methods:

[0071] The carbon isotope labeling method involves returning straw labeled with the stable isotope carbon-13 to the field, periodically collecting soil samples, and using isotope ratio mass spectrometry to determine the carbon-13 content in the newly formed soil organic matter, thereby accurately calculating the rate of straw carbon conversion to the stable soil carbon pool. The soil organic matter physical grouping combined with carbon content determination method involves periodically collecting soil samples, separating highly active particulate organic matter through physical grouping methods such as particle size density grouping, and measuring the increase in its carbon content to characterize the rate of new carbon fixation; the measurement frequency is once every seven to ten days.

[0072] In the high-efficiency carbon sequestration metabolism stage at the preset level, the preset level is a soil carbon sequestration efficiency threshold used to screen for high-efficiency stages. This threshold is determined by analyzing historical data: calculating the average soil carbon sequestration efficiency at all historical measurement time points, and initially defining the period corresponding to the efficiency value that is higher than the average value by one standard deviation as a potential high-efficiency stage; the final determination of the high-efficiency stage is combined with agronomic observations, such as good crop growth and the duration of soil carbon sequestration efficiency that is consistently higher than the preset level, for example, the efficiency is higher than the threshold in two consecutive measurement cycles. Finally, one or more high-efficiency carbon sequestration metabolism stages are delineated on the historical data timeline. These stages represent the golden period when soil microorganisms efficiently assimilate straw carbon into soil organic carbon;

[0073] From historical datasets, raw monitoring data of carbon dioxide release rate, soil redox potential, and soil temperature were extracted for each period identified as a high-efficiency carbon fixation metabolism stage. The extracted data segments were processed as follows: First, standardization was performed to eliminate dimensions; then, a dynamic time-warped centroid averaging algorithm was used to synthesize multiple signals of the same type, such as multiple carbon dioxide release curves within high-efficiency periods, into a single, representative ideal change curve. Finally, three standard-length reference sequences were obtained: an ideal carbon dioxide release rate reference sequence, an ideal soil redox potential reference sequence, and an ideal soil temperature reference sequence. These three sequences together constitute a knowledge template for high-efficiency carbon fixation metabolism signals used for real-time comparison.

[0074] Dynamic time warping is an algorithm used to calculate the similarity between two time series of different lengths. It aligns the two series by finding an optimal curved path that minimizes the cumulative distance between corresponding data points along the path; this minimum cumulative distance is the dynamic time warping distance. This algorithm effectively compares sequences that have undergone scaling or translation on the time axis. In this invention, the dynamic time warping distance is calculated between a segment of the real-time data stream up to the current moment, such as data from the last 48 hours, and the corresponding ideal reference sequence. Specifically, The distance between the real-time carbon dioxide emission rate sequence and the ideal carbon dioxide emission rate reference sequence; , And so on;

[0075] The matching degree is obtained by calculating the comprehensive morphological similarity between real-time biophysical signal data streams and efficient carbon fixation metabolism signals. The formula is: ,in, The expression for comprehensive morphological similarity is: ,in This represents the dynamic time warp distance between the time series of carbon dioxide emission rates in the real-time data stream and the corresponding ideal carbon dioxide emission rate reference series. This represents the dynamic time-warped distance between the soil redox potential time series in the real-time data stream and the corresponding ideal soil redox potential reference series. This represents the dynamic time-warped distance between the soil temperature time series in the real-time data stream and the corresponding ideal soil temperature reference series. respectively to give The weighting coefficients, and ;

[0076] The preset weight coefficients represent the importance of the three signals in judging the overall metabolic state. The weights are determined based on the correlation strength between each signal and carbon fixation efficiency in historical data analysis. For example, if the carbon dioxide release rate has the highest correlation with carbon fixation efficiency, it is given the largest weight (e.g., 0.5), and the weights of the other signals are 0.25 each. The sum of all weight coefficients is 1.

[0077] Match The formula will determine the degree of difference. Mapped to a similarity index between 0 and 1 When the real-time sequence is completely consistent with the ideal sequence, =0, A value of 1 indicates a perfect match; the greater the difference, the better. The larger the value, The closer the value is to 0, the lower the similarity.

[0078] The start and end of the window period for efficient carbon fixation metabolism are determined according to the following rules: a first threshold is set. Second threshold With the third threshold And satisfy When the matching score is higher than Drop to below When this window of efficient carbon fixation metabolism begins, a decision to apply topdressing fertilizer during this window is triggered.

[0079] For the first threshold Second threshold With the third threshold These thresholds are derived from statistical analysis of historical data used to build the knowledge base, specifically by calculating the matching degree across all historical efficient carbon sequestration metabolism stages. Value distribution characteristics; third threshold Take the historical high-efficiency stage matching degree The upper quartile (75th percentile) of the value, for example, 0.82. A value higher than this threshold indicates that the soil is in a very ideal and efficient carbon sequestration state; the first threshold. Take the historical high-efficiency stage matching degree The median or lower quartile (i.e., the 25th percentile), for example 0.68, is the critical point between a state of high efficiency and a state of decline; the second threshold Set to a significantly lower A value of , for example, 0.52, represents a level where carbon sequestration efficiency has declined to the point requiring immediate nutrient intervention. The relationship between the three thresholds is always: ;

[0080] The window period begins when the matching degree is calculated in real time. Values ​​above the first threshold The state continued to decline and fell below At this point, the system determines that the soil has left a stable and highly efficient carbon sequestration state and entered a window period of highly efficient carbon sequestration. This window period signifies that the system needs to be alerted to the decline in efficiency and prepare for intervention. During this window period, the system continuously monitors the soil, and if the matching degree... The value decreased further and fell below the second lower threshold for the first time. If this happens, the topdressing decision logic in step three will be triggered immediately, which indicates that the efficiency decline has reached the preset intervention threshold.

[0081] The window period for efficient carbon fixation metabolism refers to a continuous time period dynamically determined during the early growth stage of the crop in the current cultivation cycle. This period is calculated through real-time matching degree calculations and threshold comparisons, and extends from the point where carbon fixation efficiency begins to decline significantly until it recovers or recovers after intervention. It represents a real-time event period that is currently occurring and requires dynamic management decisions. An efficient carbon fixation metabolism window period necessarily occurs during the early growth stage of the crop in the current cultivation cycle, specifically from the time of sowing until the end of its vigorous vegetative growth period (generally around the jointing stage). It does not cover the entire cultivation cycle, and its time boundary is determined by the matching degree. The relationship between values ​​and thresholds is dynamically defined, as mentioned above: starting from... Values ​​higher than Dropped below Ending at The value rebounded to above Imagine the early growth stage of the current cultivation cycle as a timeline; on this axis, the matching degree... The value resembles an undulating curve; whenever this curve transitions from a high value region (greater than...) ) Down through When the threshold is reached, a new window period begins; it continues until it crosses the threshold again. The threshold is reached, and the window period ends; therefore, multiple downward crossings will occur on the curve. to wear The cycle is repeated, and each cycle corresponds to an independent window period.

[0082] Step 3: Continuously monitor the matching degree during the window period until it falls below the second threshold for the first time during the window period. Calculate and apply the second manure topdressing amount based on the duration of the window period and the matching degree. If the amount of the second manure topdressing applied or the matching degree is higher than the third threshold during the window period, it is determined that the window period has ended. Based on the sum of the amount of the second manure topdressing in all window periods, the initial manure application amount for the next cultivation cycle is adjusted.

[0083] This step specifically performs two key tasks: First, during each window of efficient carbon sequestration metabolism, the second topdressing of manure is calculated and implemented based on the real-time monitoring of soil conditions; second, after the end of the current cultivation cycle, the topdressing data of all windows are summarized, and the initial amount of manure applied in the next cultivation cycle is scientifically adjusted, so that the entire fertilization system has the ability to continuously optimize.

[0084] During the window of efficient carbon fixation metabolism, the matching degree was continuously monitored, and the self-matching degree was lower than [value missing]. From to its lower Stop, calculate the average of all matching degree values ​​during this decline process, and record it as the average decline in matching degree. Record the duration of this descent process, denoted as the window period descent duration. That is, within this window period, the matching degree changes from lower than From to below The duration of the stop;

[0085] The soil is considered to have left the current window of efficient carbon sequestration when any of the following conditions are met: Condition 1 is when the matching degree value is lower than... And complete the calculation and application of the second topdressing of manure; condition two is that within the window period, the matching degree value naturally rises to a level higher than After the window period ends, if the reason for the end is condition one, a fertilization response interval of a preset duration will be entered, during which the determination of the start of a new window period for efficient carbon fixation metabolism will be suspended; if the reason for the end is condition two, the determination of the start of a new window period for efficient carbon fixation metabolism will be resumed immediately.

[0086] The fertilization response interval is a preset time period, such as 3 days (72 hours). It represents the approximate time from the completion of the second topdressing of manure in the field to the expected impact of this fertilization on soil microbial activity, that is, the time required to reflect the matching degree value. This interval is set to give the soil microbial community enough response time and avoid invalid state judgment immediately after fertilization.

[0087] The criteria for determining the end of the window period are as described above. The current window period for efficient carbon fixation metabolism is considered to have ended when any of the following conditions are met: Condition 1 (post-intervention decision completed): During the window period, when the real-time matching degree value first falls below the second threshold. Furthermore, the calculation and field application of the second manure topdressing amount for this decrease have been completed. Once the fertilization operation is completed, the current window period for efficient carbon sequestration metabolism will be immediately determined to have ended; Condition two (natural state transition): during the window period, even if topdressing is not triggered or has not yet been carried out, if the matching degree value naturally rises to above the third threshold... This also immediately indicates that the current window of efficient carbon fixation metabolism has ended;

[0088] After the window period ends, two different follow-up monitoring strategies are adopted depending on the reason for the end, to reasonably connect the subsequent state judgment: If the window period ends due to condition one (completion of topdressing): a preset fertilization response interval will be initiated. This interval is a fixed duration, for example, set to 72 hours. The main purpose of this interval is not to wait for the soil state to recover, but to actively pause the initiation of the new window period judgment logic. This is because the newly applied manure needs time to mix with the soil and initiate its nutrient release and microbial activation processes. During this stage when the physical and biochemical processes are not yet stable, the soil's biophysical signals (matching degree) will be in an atypical transitional state. If the start of a new window period is immediately judged based on this state, it is very easy to make a misjudgment. Therefore, during the entire fertilization response interval, the execution of step two, "when the matching degree is lower than the first threshold," will be suspended. The logic of "determining when the soil enters a window period of efficient carbon sequestration metabolism" will not open a new window period regardless of how the matching degree fluctuates during this period. After the fertilization response interval ends, the normal window period start determination function will be automatically restored.

[0089] If the window period ends due to condition two (natural recovery), this indicates that the soil carbon sequestration metabolism has recovered to an efficient level without intervention. Therefore, there is no need to wait. Immediately after the window period ends, resume the judgment logic for the start of a new window period in step two. The system can immediately begin monitoring whether the matching degree falls below a certain level again. This allows them to prepare for the next window of opportunity when efficiency declines.

[0090] Repeat the above operations during the early growth stage of the crop in the current cultivation cycle to identify multiple windows of efficient carbon fixation metabolism.

[0091] The specific method for calculating the amount of the second topdressing of manure is determined by the following formula:

[0092]

[0093] in, This refers to the amount of the second manure topdressing calculated when the topdressing decision is triggered during the i-th window period. This is the initial amount of manure applied. Let be the average of all matching scores within the descent duration of the i-th window period. The first threshold, For the duration of the descent during the i-th window period, This represents the expected typical duration based on crop variety and local climate conditions. and The adjustment coefficient is , and satisfies . ;

[0094] Mean decrease in matching degree The value is obtained when the matching degree value first falls below the first threshold during the i-th window period. From that moment on, the system enters continuous monitoring mode, and will record the data until the matching degree value first falls below the second threshold. Throughout the entire descent phase, the matching degree value is recorded at each sampling time (e.g., every hour), and then the arithmetic mean of these recorded matching degree values ​​is calculated. This average value is the mean descent of the matching degree. This parameter quantitatively describes the average degree to which the soil carbon sequestration metabolism deviates from the ideal and efficient state during the decline phase of this window period. The lower the value, the worse the average soil carbon sequestration efficiency during this decline phase, and the stronger the need for intervention through exogenous nutrient input.

[0095] For the duration of the descent The total time elapsed during the aforementioned descent phase, as recorded in the log, is the descent duration. For example, if the match rate is lower than 10% on Monday morning On Wednesday afternoon, below ,but The timeframe is approximately 2.5, reflecting the time it takes for soil carbon sequestration efficiency to decline before triggering a topdressing decision. The length of time implies the soil system's inherent buffering capacity against efficiency decline, or the rate at which environmental pressure accumulates.

[0096] Typical duration expected value It is a preset reference duration based on specific crop varieties and climatic conditions of the planting area. Its purpose is to provide a reference for the actual duration of decline during different window periods. Provide a normalized benchmark, The specific values ​​were obtained by analyzing historical data: data on the duration of declines in all efficient carbon fixation metabolism windows that occurred during multiple past cultivation cycles of this crop in the region were collected, and the average or median of these durations was calculated. This statistical value was then set as... For example, in spring cornfields in Changtu County, Liaoning Province, analysis of data from the past five years revealed that the duration of the decline during the window period is mostly between 3 and 6 days, with an average of approximately 4.5 days. The default value is 4.5;

[0097] and These are two pre-defined constants that satisfy the following relation: , This represents the weight of the degree of decrease in matching degree in the calculation of topdressing amount. This represents the weight of the duration of the decline in the calculation of the topdressing amount. For example, if agronomic experience suggests that the severity of the deviation from the ideal soil condition is more important than the duration of the deviation, then this is set... , The initial values ​​of these coefficients are determined based on expert experience or small-scale trials, and are fine-tuned and optimized through the cross-cycle learning mechanism that will be introduced later.

[0098] The matching degree was calculated from the initial downward threshold. Average value during the decline phase The decrease, divided by Normalization was achieved, and the relative decrease ratio was obtained. The larger the value, the more serious the deviation of the soil carbon sequestration metabolism from the efficient ideal state during the window period, and therefore the stronger the demand for topdressing intervention. It reflects the relative rate of state decline. It is the ratio of the actual descent duration to the typical duration. Less than The rate of descent is faster than in typical cases. A positive and relatively large value indicates a sharp decline in soil carbon sequestration efficiency within a short period, and a sudden and rapid loss of system stability. Therefore, stronger and more timely topdressing incentives are needed to quickly curb the decline. near The descent rate is typically... Approaching zero, this contribution is negligible; when Greater than When the descent rate is slower than typical, A negative value indicates that efficiency decline is a slow, long-term process, suggesting that the soil system itself has a certain buffering or resistance capacity, and its urgency is low. Therefore, this item will have a weakening effect on the total incentive coefficient, thereby reducing the recommended amount of topdressing.

[0099] The formula weighted sums of the two parts, and the resulting dynamic intensity coefficient comprehensively reflects the dynamic fertilization incentive intensity assessed based on the depth and speed of deterioration within the current window period. Finally, the initial manure application rate is considered. Multiplying by this dynamic intensity coefficient yields the recommended amount of second manure topdressing for this specific window period. This means that the amount of topdressing fertilizer is a dynamic ratio of the amount of base fertilizer, and this ratio is determined by the real-time monitoring status.

[0100] The method for dynamically calculating the amount of the second manure topdressing also includes an ecological safety constraint step: pre-setting a maximum topdressing limit based on the soil's environmental carrying capacity. For any given window period, if the amount of the second manure topdressing calculated according to the formula is greater than... The amount of the second top dressing of manure finally implemented during this window period shall be adopted. value;

[0101] Maximum fertilizer application limit This is a safety limit set to prevent environmental pollution caused by excessive single fertilization, such as nitrogen and phosphorus runoff and heavy metal accumulation. This limit is determined comprehensively based on local environmental protection regulations, soil heavy metal background values, and research on the nutrient and environmental carrying capacity per unit area of ​​arable land; it is an absolute value. For the theoretical amount of the second topdressing calculated for each fertilization window, the system will compare it with... If a comparison is made, Then according to Apply topdressing; if Therefore, the actual amount of topdressing during this window period will be limited to This ensures that fertilization operations are always carried out within environmental safety limits.

[0102] make , , , Set the matching degree descent depth to The proportion of the descent time is The proportion of topdressing fertilizer to base fertilizer is Then the formula simplifies to: Specific data on the window period and the proportion of topdressing to base fertilizer are shown in Table 1.

[0103] Table 1 Statistical Data

[0104]

[0105] Because of the second term in the formula The value range includes negative values, and the weight... This leads to the calculated Negative values ​​may occur (such as windows 1, 6, 11, etc.), which in turn... In practical applications, the amount of topdressing fertilizer should be non-negative. Item design or parameters In the settings, it has been ensured that it is consistent with After weighted summation of terms, the dynamic intensity coefficient It is a non-negative value, adjusted by the expected value of typical duration. The value, or in practical applications, the dynamic intensity coefficient. To achieve this, a non-negative lower bound (e.g., 0) is set, thus ensuring that the recommended amount of topdressing always has practical significance (non-negative).

[0106] Analysis of the first 15 sets of data reveals a clear internal relationship and pattern between the parameters characterizing soil carbon sequestration and metabolism and the final decision on topdressing ratio. Firstly, the relationship between the average matching degree and the depth of matching degree decline shows opposite trends. When the average matching degree is low, for example, in the range of 0.5 to 0.52, the corresponding depth of matching degree decline is large, between 0.257 and 0.286, indicating a significant deviation of the soil's carbon sequestration and metabolism from the ideal efficient model. Conversely, when the average matching degree increases to 0.58 to 0.59, the depth of decline decreases to 0.157 to 0.171, indicating a shallower deviation. This intuitively reflects the consistency within the state assessment indicators.

[0107] Secondly, observing the relationship between the duration of descent and its proportion reveals that as the duration of descent increases, the proportion of descent duration decreases. For example, when the duration of descent is 1 day, the proportion is a neutral zero; when the duration increases to 1.5 days, the proportion decreases to -0.1; when the duration further reaches 2 days, the proportion drops to -0.2. This trend indicates that a longer descent process often corresponds to a relatively slower descent rate.

[0108] Most importantly, the final calculated ratio of topdressing to base fertilizer is influenced by the combined effects of the two factors mentioned above. The data in the table shows that during the window periods when the matching degree declines significantly, such as data groups 4, 10, and 14, although the proportion of decline duration may be zero or slightly negative, the final topdressing ratio is still at a high level. This indicates that the severity of state deterioration is the fundamental factor driving the topdressing decision. At the same time, when the matching degree declines at similar depths, the difference in the proportion of decline duration also has a moderating effect on the final topdressing ratio. For example, comparing data groups 1 and 11, both have the same decline depth, but the latter's proportion of decline duration is slightly lower than the former, and its final topdressing ratio is also slightly lower. This reflects the system's response to the rate of state decline, that is, the more urgent the decline process, the stronger the incentive to provide topdressing.

[0109] In summary, the data shows that topdressing decisions are not determined by a single factor, but rather by the combined effect of the depth of the soil carbon sequestration state deviating from the ideal level and the speed at which the deviation occurs. The deeper and faster the state deteriorates, the stronger the nutrient intervention recommended by the system will be. This constitutes the core logic of dynamic topdressing regulation.

[0110] Furthermore, the method for generating the initial application rate correction value for the next cultivation cycle is defined by the following formula: Calculate the sum of the second manure topdressing amounts corresponding to all window periods within the current cultivation cycle, denoted as... Calculate the arithmetic mean of the decline durations corresponding to all windows within the current cultivation cycle, and denot it as the average decline duration. ;

[0111] The formula for calculating the recommended initial manure application rate for the next cultivation cycle is as follows:

[0112]

[0113] in, This indicates the initial amount of manure to be applied after adjusting for the next season's cultivation cycle. This refers to the total number of growing days in the current cultivation cycle from sowing to the critical nitrogen-required period. Learning rate coefficient for soil basic nitrogen supply capacity;

[0114] After the current cultivation cycle ends, the system will calculate the actual amount of the second manure topdressing applied during all efficient carbon fixation metabolism windows within this cycle (i.e., the amount already applied). The constrained values ​​are summed to obtain the total amount of fertilizer applied in a given period. It quantifies the total amount of extra manure input in the current season to address the decline in carbon sequestration efficiency;

[0115] Calculate the descent duration for all windows within this period. The arithmetic mean of the values ​​is used to obtain the average descent time. It reflects the overall and persistent characteristics of the decline in soil carbon sequestration efficiency during the current season; total growing days This refers to the total number of days from the sowing date of the current cultivation cycle to the nitrogen-critical period described in step 4. This is a known agronomic parameter closely related to the growth period characteristics of crop varieties. For example, for a certain spring maize variety, it takes 65 to 75 days from sowing to tasseling (i.e., the nitrogen-critical period). A specific value, such as 70 days, can be determined based on the variety instructions or local observation data.

[0116] Learning rate coefficient of soil basic nitrogen supply capacity It is a constant with a value between 0.1 and 0.3. It controls the extent to which the amount of base fertilizer for the next season is adjusted based on the feedback information of the current season. It aims to achieve a smooth and gradual optimization and avoid over-adjustment due to the accidental fluctuations of single-season data.

[0117] This is the ratio of the total amount of topdressing fertilizer applied in the current season to the initial amount of basal fertilizer. A larger ratio indicates that, under the current management conditions, multiple or large amounts of topdressing fertilizer are needed to maintain carbon sequestration efficiency, which suggests the initial amount of manure applied. The setup failed to adequately meet the early needs of soil microorganisms, or the soil's own basic nitrogen supply capacity was relatively limited; It is the proportion of the average decline time in the current season to the total time from sowing to the critical period of nitrogen requirement. When this proportion is large, it indicates that the soil carbon sequestration efficiency is poor for a large part of the early growth period, reflecting the insufficiency of soil health or basic fertility. The product of the two constitutes a comprehensive evaluation index. The higher the index, the more it indicates that the soil in the current field is characterized by: low basic nitrogen supply potential and poor carbon sequestration metabolism stability in the current season, thus being more dependent on dynamic topdressing.

[0118] Formula used The initial manure application rate is expressed as an exponential factor. The reduction means that when the above composite index is high (indicating soil dependence on topdressing), the initial manure application rate for the next season should be reduced. The amount will be appropriately reduced. The underlying strategy of this design is: for soils with weak self-sustaining capacity, instead of investing a large amount of base fertilizer in the early stage (its nutrients cannot be effectively utilized or face the risk of loss when microbial activity is low), it is better to store some nutrients and then apply them dynamically and precisely during the monitored window of efficient carbon fixation metabolism. This way, the limited nutrient resources are used where they are most needed, that is, when microbial activity is highest, demand is most urgent, and the potential for improving carbon fixation efficiency is greatest.

[0119] Step 4: Before the crop enters its critical nitrogen-requiring period in the current cultivation cycle, measure the available nitrogen content in the topsoil. Compare this measured value with the total amount of nitrogen that the crop needs to absorb from the critical nitrogen-requiring period until maturity. Based on the comparison results and the actual implementation of the topdressing decision, determine and quickly supplement the third final fertilizer application amount in the form of chemical fertilizer to complete the fertilization and ensure the final yield of the current cultivation cycle.

[0120] This step is the final execution stage of the technical route of this invention. Its core objective is to quickly supplement fast-acting nitrogen fertilizer through accurate nutrient accounting at the most critical stage of crop yield formation, so as to ensure the final yield and complete the archiving of data for the entire cultivation cycle for system self-learning optimization.

[0121] Acquire and record details of each second topdressing application event actually triggered within each efficient carbon fixation metabolism window, including the amount of manure applied each time and its corresponding specific date; for each application event, based on the total nitrogen content of the batch of manure, the duration from the fertilization date to the critical nitrogen requirement period, and the average temperature during this period, estimate the amount of effective nitrogen that the applied manure is expected to release before the critical nitrogen requirement period in this application event using a mineralization model, as the single effective nitrogen supply;

[0122] The cumulative effective nitrogen supply is obtained by summing up the single effective nitrogen supply corresponding to all such application events within the current cultivation cycle. Finally, the measured available nitrogen content in the topsoil and this cumulative effective nitrogen supply are considered as the total effective nitrogen supply in the soil. This is then deducted from the total nitrogen required by the crop from the critical period of nitrogen demand until maturity. The resulting net nitrogen requirement difference is the amount of the third final fertilizer application that needs to be quickly supplemented in the form of chemical fertilizer. If there is no difference or the result is negative, then no chemical fertilizer is needed, and the amount of the third final fertilizer application is 0.

[0123] The critical period for nitrogen requirement refers to an irreversible physiological stage in crop growth and development where the crop is most sensitive to nitrogen supply, absorbs nitrogen at the fastest rate, and has the greatest impact on final economic yield. During this period, the crop accelerates its transition from vegetative growth to reproductive growth, and reproductive organs such as young spikes and florets are differentiating and forming. If nitrogen supply is insufficient at this time, it will directly lead to a reduction in the number of grains per spike, resulting in irreversible yield loss; if the supply is excessive, it is prone to causing late maturity or lodging. The critical period for nitrogen requirement is determined by the inherent genetic growth period characteristics of crop varieties. For different crops, the critical period for nitrogen requirement corresponds to specific phenological stages that are easily identifiable in the field: for example, the critical period for nitrogen requirement of maize is generally from the large trumpet stage to the tasseling stage, at which time the plant can see the 11th-12th leaves unfolding and the tassel is about to emerge; the critical period for nitrogen requirement of rice is generally at the early stage of young spike differentiation, at which time field observation combined with leaf age index, for example, when the leaf age remainder of the main stem is about 3.5, is used to determine the critical period for nitrogen requirement of wheat; the critical period for nitrogen requirement of wheat is generally from the jointing stage to the booting stage.

[0124] When implementing this invention, it is necessary to determine the field morphological standard or growth day range corresponding to the critical nitrogen requirement period before sowing, based on the specific crop variety being planted, and set it as the fixed time node for soil testing and supplementary fertilization in step 4. For example, for a certain spring maize variety, the day when more than 50% of the plants in the field reach the large trumpet stage can be defined as the starting date of the critical nitrogen requirement period in the current cultivation cycle.

[0125] The available nitrogen content in the topsoil was determined 3-5 days before the start of the critical nitrogen requirement period. A mixed sample of topsoil from the 0-20 cm depth was collected according to standard soil sampling methods. The available nitrogen content was determined using the alkaline hydrolysis-diffusion method, and the result was converted to a value per unit area and recorded as follows: Total nitrogen requirement of crops, specifically referring to the total amount of nitrogen required by crops from the critical nitrogen-demand period until physiological maturity, is denoted as […]. This value needs to be calculated based on the nitrogen uptake curve model of the target yield and crop variety. A simplified method is to first calculate the total nitrogen requirement for the entire growth period (same as step 1), and then multiply it by an empirical proportion. For example, the amount of nitrogen absorbed by corn after the large tasseling stage accounts for about 60%-70% of the total nitrogen requirement for the entire growth period, thereby estimating the nitrogen requirement. ;

[0126] Each instance of dynamic topdressing in step 3 constitutes an independent application event. Each application event is automatically recorded as a data entry in the system and must include two core fields: the amount of the second topdressing applied, i.e., the actual amount of manure applied to the field, which is subject to the maximum topdressing limit. Constraints; the specific date of this fertilization, i.e., the calendar date on which the topdressing operation is completed;

[0127] Estimating the subsequent nitrogen supply (cumulative effective nitrogen supply) of previously applied manure is crucial for precise supplementation. The principle is to calculate how much nitrogen from all previously applied manure has been or is about to be converted into a form absorbable by the crop during the critical nitrogen-demand period; and for each recorded application event (e.g., application event j), the expected effective nitrogen supply during the critical nitrogen-demand period. Estimate using the formula: ,in This refers to the amount of manure applied as a second top dressing during this application event. The total nitrogen content of this batch of manure is a percentage by mass. It is obtained by taking a representative sample and sending it to the laboratory before applying this batch of manure. The Kjeldahl method is used to determine the percentage of total nitrogen content to wet weight. This is a known constant obtained directly through laboratory testing.

[0128] Mineralization coefficient It is a value between 0 and 1, representing the proportion of nitrogen mineralized and released as available nitrogen in this batch of manure from the fertilization date to the critical period of nitrogen requirement; This refers to the number of days elapsed from the date of fertilization to the start date of the critical period for nitrogen requirement. In order to be in During this period, the arithmetic mean of the daily average soil temperature in the topsoil layer is obtained from the monitoring nodes set up in step 2.

[0129] Mineralization coefficient It is time ( ) and temperature ( A commonly used empirical model for the function of exponential growth is the exponential growth model: ,in, It is the maximum mineralization potential coefficient (related to the maturity of manure). Let be the mineralization rate constant. The temperature coefficient (set to 2, indicating that the mineralization rate doubles for every 10°C increase in temperature), parameter and The results were obtained through local manure decomposition experiments. In practical applications, a system based on prior experiments should be established. and The system uses a lookup table for input variables and interpolation to determine the event for each event. value;

[0130] Calculation of cumulative effective nitrogen supply: This includes all application events corresponding to the current cultivation cycle. Adding them together gives the cumulative effective nitrogen supply from all dynamic topdressing. ;

[0131] According to the principle of nutrient balance, the amount of readily available nitrogen fertilizer (the third final fertilizer) that needs to be supplemented should equal the crop's requirements minus all known supply sources. Therefore, the amount of the third final fertilizer applied... (Based on pure nitrogen) It is determined by the following formula:

[0132]

[0133] The function ensures that the calculation result is non-negative, meaning that fertilizer supplementation is only needed when the predicted supply is insufficient. When the value within the parentheses in the formula is positive, it indicates that the sum of the soil's baseline supply and the expected supply from the applied manure is insufficient to meet the crop's needs; the difference is the amount of pure nitrogen that needs to be supplemented. When the value inside the parentheses is zero or negative, it indicates that the predicted supply is sufficient or excessive. The function will Setting it to 0 means no further fertilizer is needed, thus avoiding over-fertilization; the calculation... Then, based on the nitrogen content of the selected fertilizer (such as urea, which contains 46% nitrogen), calculate the specific amount of fertilizer to be applied and apply it to the soil as soon as possible at the beginning of the critical period for nitrogen demand.

[0134] After completing a full cultivation cycle, the numerical sequence of actual matching degree obtained during the current cultivation cycle, the actual duration of the window period, the actual amount of fertilizer applied, and the final yield data are entered into the database. Regression analysis is then used to analyze the accumulated data... , , , , and Perform periodic calibration and optimization;

[0135] The system archives the complete dataset generated within the current cultivation cycle, including continuous time series of matching degree values, actual start and end times of each window of efficient carbon fixation metabolism, duration of decline, initial manure application amount, amount and date of the second manure application for each topdressing, and amount of the third final fertilizer application. And the final actual crop yield;

[0136] The system utilizes a historical database accumulated over a long period of time across multiple cultivation cycles, periodically (e.g., after accumulating 3-5 cycles of data) to run a regression analysis model and automatically calibrate and optimize the following core parameters: state determination threshold. The optimization goal is to make these threshold settings more accurately predict yield and carbon sequestration performance. For example, by analyzing the relationship between the matching degree sequence and the final yield in historical data, the critical matching degree point that best distinguishes between high-yield and low-yield states can be found, thereby adjusting the thresholds; the calculation coefficient of topdressing amount... and The optimization objective is to optimize the amount of manure applied in each subsequent topdressing. The nutrient content is more accurately matched to the actual amount required to achieve optimal carbon sequestration and restoration, through analysis of different... and Under the combined approach, the relationship between the rate of end of the post-fertilization window (recovery efficiency) and the total amount of topdressing in the current season was optimized; the learning rate coefficient of soil basic nitrogen supply capacity was also analyzed. The optimization goal is to enable the cross-cultivation cycle basal fertilizer adjustment strategy to converge the system to the optimal initial fertilization amount more quickly and stably. This is achieved by analyzing different... The value is determined by the fluctuation of the initial manure application rate in multiple consecutive cultivation cycles and its relationship with yield stability.

[0137] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0138] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0139] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0140] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements, characterized in that, The specific steps include: Step 1: After completing the straw return operation of the previous crop, before sowing the current crop, based on the soil background organic carbon content and the total nitrogen requirement corresponding to the target yield, calculate and apply the initial amount of manure fertilizer by activating the target through the preset carbon-nitrogen ratio. Step 2: In the early stage of crop growth during the current cultivation cycle, continuously collect biophysical signals in the soil that characterize the intensity of microbial carbon fixation metabolism. Calculate the matching degree between the real-time data stream of the acquired biophysical signals and the high-efficiency carbon fixation metabolism signals. When the matching degree is lower than the first threshold, determine that the soil has entered the window period of high-efficiency carbon fixation metabolism and execute the topdressing decision in Step 3. Step 3: Continuously monitor the matching degree during the window period until it falls below the second threshold for the first time during the window period. Calculate and apply the second manure topdressing amount based on the duration of the window period and the matching degree. If the amount of the second manure topdressing applied or the matching degree is higher than the third threshold during the window period, it is determined that the window period has ended. Based on the sum of the amount of the second manure topdressing in all window periods, the initial manure application amount for the next cultivation cycle is adjusted. Step 4: Before the crop enters its critical nitrogen-requiring period in the current cultivation cycle, measure the available nitrogen content in the topsoil. Compare this measured value with the total amount of nitrogen that the crop needs to absorb from the critical nitrogen-requiring period until maturity. Based on the comparison results and the actual implementation of the topdressing decision, determine and quickly supplement the third final fertilizer application amount in the form of chemical fertilizer to complete the fertilization and ensure the final yield of the current cultivation cycle. The specific method for calculating the amount of the second topdressing of manure is determined by the following formula: in, This refers to the amount of the second manure topdressing calculated when the topdressing decision is triggered during the i-th window period. This is the initial amount of manure applied. Let be the average of all matching scores within the descent duration of the i-th window period. The first threshold, For the duration of the descent during the i-th window period, This represents the expected typical duration based on crop variety and local climate conditions. and The adjustment coefficient is , and satisfies . ; Specifically, a third threshold is set to be greater than the first threshold, and the first threshold is greater than the second threshold. Based on the actual implementation of the topdressing decision, the effective nitrogen that can be mineralized and released before the critical nitrogen demand period of each topdressing is estimated by the mineralization model according to the amount and date of each second topdressing application, and the cumulative effective nitrogen supply is obtained by summing them up. The third final fertilizer application amount is the difference between the total nitrogen demand of the crop and the sum of the measured value of available nitrogen content in the topsoil and the cumulative effective nitrogen supply.

2. The method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements according to claim 1, characterized in that: The initial amount of manure to be applied is calculated based on the soil's background organic carbon content and the total nitrogen requirement corresponding to the target yield. The specific procedure is as follows: After completing the straw return operation of the previous crop, before sowing the crop in the current cultivation cycle, soil samples of the topsoil are collected and tested to obtain the background organic carbon content of the soil, set the target yield for the current cultivation cycle, and calculate the total nitrogen requirement by combining the nitrogen absorption parameters required for the crop variety to achieve a unit yield in the current cultivation cycle. The initial manure application rate is calculated with the goal of simultaneously satisfying the following two conditions: Condition 1 is that the ratio of total organic carbon to total available nitrogen contained in the soil background organic carbon, straw returned to the field and initial manure is within a preset carbon-nitrogen ratio range that can stimulate the initial activity of soil microorganisms; Condition 2 is that the amount of nitrogen supplied by the initial manure accounts for a preset ratio range of the total nitrogen demand.

3. The method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements according to claim 2, characterized in that: The matching degree of the acquired real-time biophysical signal data stream is calculated with the efficient carbon fixation metabolism signal. The specific operation is as follows: in-situ monitoring nodes are set up in the field to synchronously and continuously collect signal data of carbon dioxide release rate, soil redox potential and soil temperature in the soil at a set frequency to form a real-time biophysical signal data stream. The efficient carbon fixation metabolism signal is obtained in advance by means of the following method: During the historical cultivation cycle, the efficient carbon fixation metabolism stage in which the soil carbon fixation efficiency of soil microorganisms is consistently higher than the preset level is identified. Typical change sequences of carbon dioxide release rate, soil redox potential and soil temperature obtained by synchronous monitoring during this stage are extracted and used as ideal carbon dioxide release rate reference sequence, ideal soil redox potential reference sequence and ideal soil temperature reference sequence, respectively, to constitute the efficient carbon fixation metabolism signal. The matching degree is obtained by calculating the comprehensive morphological similarity between real-time biophysical signal data streams and efficient carbon fixation metabolism signals. The formula is: ,in, The expression for comprehensive morphological similarity is: ,in This represents the dynamic time warp distance between the time series of carbon dioxide emission rates in the real-time data stream and the corresponding ideal carbon dioxide emission rate reference series. This represents the dynamic time-warped distance between the soil redox potential time series in the real-time data stream and the corresponding ideal soil redox potential reference series. This represents the dynamic time-warped distance between the soil temperature time series in the real-time data stream and the corresponding ideal soil temperature reference series. respectively to give The weighting coefficients, and .

4. The method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements according to claim 3, characterized in that: The start and end of the window period for efficient carbon fixation metabolism are determined according to the following rules: a first threshold is set. Second threshold With the third threshold And satisfy When the matching score is higher than Drop to below When this window of efficient carbon fixation metabolism begins, a decision to apply topdressing fertilizer during this window is triggered. During this window period, the matching degree is continuously monitored; the self-matching degree is lower than... From to its lower Stop, calculate the average of all matching degree values ​​during this decline process, and record it as the average decline in matching degree. Record the duration of this descent process, denoted as the window period descent duration. That is, within this window period, the matching degree changes from lower than From to below The duration of the stop; The soil is considered to have left the current window of efficient carbon sequestration when any of the following conditions are met: Condition 1 is when the matching degree value is lower than... And complete the calculation and application of the second topdressing of manure; condition two is that within the window period, the matching degree value naturally rises to a level higher than After the window period ends, if the reason for the end is condition one, a fertilization response interval of a preset duration will be entered, during which the determination of the start of a new window period for efficient carbon fixation metabolism will be suspended; if the reason for the end is condition two, the determination of the start of a new window period for efficient carbon fixation metabolism will be resumed immediately. Repeat the above operations during the early growth stage of the crop in the current cultivation cycle to identify multiple windows of efficient carbon fixation metabolism.

5. The method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements according to claim 4, characterized in that: The method for adjusting the initial application rate for the next cultivation cycle is defined by the following formula: Calculate the sum of the second manure topdressing amounts corresponding to all window periods within the current cultivation cycle, denoted as... Calculate the arithmetic mean of the decline durations corresponding to all windows within the current cultivation cycle, and denot it as the average decline duration. ; The formula for adjusting the initial application rate for the next cultivation cycle is as follows: in, This indicates the initial amount of manure to be applied after adjusting for the next season's cultivation cycle. This refers to the total number of growing days in the current cultivation cycle from sowing to the critical nitrogen-required period. Learning rate coefficient for soil basic nitrogen supply capacity; The method for dynamically calculating the amount of the second manure topdressing also includes an ecological safety constraint step: pre-setting a maximum topdressing limit based on the soil's environmental carrying capacity. For any given window period, if the amount of the second manure topdressing calculated according to the formula is greater than... The amount of the second top dressing of manure finally implemented during this window period shall be adopted. value.

6. The method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements according to claim 5, characterized in that: Acquire and record details of each second topdressing application event actually triggered within each efficient carbon fixation metabolism window, including the amount of manure applied each time and its corresponding specific date; for each application event, based on the total nitrogen content of the batch of manure, the duration from the fertilization date to the critical nitrogen requirement period, and the average temperature during this period, estimate the amount of effective nitrogen that the applied manure is expected to release before the critical nitrogen requirement period in this application event using a mineralization model, as the single effective nitrogen supply; The cumulative effective nitrogen supply is obtained by summing up the single effective nitrogen supply corresponding to all such application events within the current cultivation cycle. Finally, the measured available nitrogen content in the topsoil and this cumulative effective nitrogen supply are considered as the total effective nitrogen supply in the soil. This is then deducted from the total nitrogen required by the crop from the critical period of nitrogen demand until maturity. The resulting net nitrogen requirement difference is the amount of the third final fertilizer application that needs to be quickly supplemented in the form of chemical fertilizer. If there is no difference or the result is negative, then no chemical fertilizer is needed, and the amount of the third final fertilizer application is 0.

7. The method for regulating fertilization based on soil carbon sequestration rate and soil manure nutrient requirements according to claim 1, characterized in that: After completing a full cultivation cycle, the numerical sequence of actual matching degree obtained during the current cultivation cycle, the actual duration of the window period, the actual amount of fertilizer applied, and the final yield data are entered into the database. Regression analysis is then used to analyze the accumulated data... , , , , and Perform periodic calibration and optimization.

Images