Nitrogen fertilizer application comprehensive benefit evaluation method based on CBA cost benefit analysis

Abstract

The invention discloses a nitrogen fertilizer application comprehensive benefit evaluation method based on CBA cost-benefit analysis, and relates to the technical field of nitrogen fertilizer application benefit evaluation, and the method comprises the following steps: determining an evaluation target, and identifying cost and income; collecting basic data; establishing a CBA cost benefit analysis model; determining crop marginal yield earnings, predicting crop price changes by using an exponential smoothing model, predicting results by using a machine model, and determining a relationship between crop yield and nitrogen application amount; determining the fertilizer cost, and predicting the fertilizer price by using an ARIMA model; the environment cost is quantified; calculating the comprehensive income of the nitrogen fertilizer; calculating a net present value NPV and a benefit cost ratio BRC; calculating output reduction loss; carrying out uncertainty analysis and sensitivity analysis; through the above steps, positive economic feedback brought by crop yield and negative economic feedback brought by environmental pollution are comprehensively considered, and the benefit index is presented by taking RMB as a measure, so that unnecessary economic loss and environmental destruction are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of nitrogen fertilizer application benefit evaluation, and in particular to a nitrogen fertilizer application comprehensive benefit evaluation method based on CBA cost-benefit analysis. Background Art

[0002] Currently, with the global population growth and changes in consumption patterns, the need to increase crop yields is becoming increasingly urgent. Nitrogen fertilizer is one of the most widely used fertilizers in agricultural production. It is essential to increase crop yields, especially the yields of major food crops such as wheat, corn and rice. However, excessive application of nitrogen fertilizer has become a serious problem, which not only leads to increased agricultural production costs, but also may cause environmental problems such as soil acidification and water eutrophication. Due to factors such as increased production, market fluctuations, and environmental damage, the economic benefits of nitrogen fertilizer application are difficult to accurately evaluate.

[0003] In related technologies, the economic benefit evaluation of nitrogen fertilizer application mainly relies on accurate field test data and manual judgment, which results in large errors. At the same time, through field tests, a relationship model between nitrogen fertilizer application and crop yield is established, which makes it difficult to accurately evaluate the impact of market price fluctuations on the economic benefits of nitrogen fertilizer, and has large uncertainties. Environmental costs are difficult to quantify and directly affect the calculation of economic benefits. Existing evaluation methods ignore the negative feedback effects of nitrogen fertilizer application on the environment, which can easily cause unnecessary economic losses and environmental damage. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for evaluating the comprehensive benefits of nitrogen fertilizer application based on CBA cost-benefit analysis, comprising the following steps: S1. Determine the evaluation objectives and identify the costs and benefits of nitrogen fertilizer application; S2. Collect basic data, including crop types, nitrogen fertilizer prices, and crop prices; S3. Establish a CBA cost-benefit analysis model; S4. Determine the marginal yield of crops, use exponential smoothing models to predict crop price changes, use machine models to predict results, and determine the relationship between crop yield and nitrogen application; S5. Determine fertilizer cost and use ARIMA model to predict fertilizer price; S6. Quantify environmental costs and calculate the cost of environmental pollution control; S7. Calculate the comprehensive benefits of nitrogen fertilizer; S8. Calculate the net present value and benefit-cost ratio; S9. Calculate the loss of production reduction and economic losses and calculate the net loss comprehensively; S10. Conduct uncertainty analysis and sensitivity analysis.

[0005] The technical solution further defined in the present invention is: Furthermore, in step S1, the cost of nitrogen fertilizer application includes direct cost and indirect cost, where the direct cost is the purchase and application cost of nitrogen fertilizer M f , the indirect cost is the environmental loss control cost M e ; The benefits include direct benefits and indirect benefits. The direct benefits are the income brought by the increase in crop yields, that is, the crop yield benefits M ra , indirect benefits are social benefits brought about by environmental improvement; Quantify crop yield benefits M ra (F a (N),P ar ) is influenced by the marginal product F a (N) and wheat price P ar , quantify the purchase and application costs of nitrogen fertilizer M f (N ar ,P f ) is influenced by the fertilizer price P f and nitrogen application rate N ar , quantify the cost of environmental loss governance ∑M e (F e (N),P e ) is the environmental effect loss equivalent F e (N) and the environmental cost of this effect P e function.

[0006] As described above, in the method for evaluating the comprehensive benefit of nitrogen fertilizer application based on CBA cost-benefit analysis, in step S3, a CBA cost-benefit analysis model is established to calculate the net benefit of nitrogen fertilizer, and the nitrogen fertilizer cost and environmental cost are deducted from the yield benefit of nitrogen fertilizer according to the following formula: N xe =M ra (F a (N),P ar )-M f (N ar ,P f )-∑M e (F e (N),P e ) Among them, M ra is the marginal output benefit of the crop, which is the marginal output F a (N) and crop price P ar Function of M f is the fertilizer cost, is the fertilizer price P f Function of nitrogen application rate N; M e is the environmental cost of the marginal loss of nitrogen fertilizer, and is the environmental loss equivalent F e(N) and the environmental cost of this effect P e function.

[0007] As described above, in a comprehensive benefit evaluation method for nitrogen fertilizer application based on CBA cost-benefit analysis, in step S4, marginal analysis is used to evaluate the marginal yield brought by each additional unit of nitrogen fertilizer input to determine the marginal yield benefit of crops; a functional relationship between yield and nitrogen application amount is established, and the marginal yield benefit is obtained as the yield benefit R yield : R yield =P yield ×(Y max -Y base ) Among them, P yield is the crop market price, Y max is the maximum output, Y base is the base output; Quantify the dynamics of crop market purchase prices and nitrogen fertilizer prices to obtain dynamic price benefits R yield (t): R yield (t) = P yield (t)×(Y max -Y base ) Apply the exponential smoothing formula for iterative calculation to predict crop price changes, determine the relationship function between crop yield, marginal yield and crop price, and determine the marginal yield benefit M of the crop. ra .

[0008] As described above, in a comprehensive benefit evaluation method for nitrogen fertilizer application based on CBA cost-benefit analysis, in step S5, the crop market purchase price is predicted to be dynamic, and the crop purchase price is set to P yield (t), P yield (t)=f 1 (t), f 1 (t) is a price function that changes over time; to predict the dynamic price of nitrogen fertilizer, let the nitrogen fertilizer price be P N (t), P N (t)=f 2 (t), f 2 (t) is a time-varying price function; The dynamic price cost in the model and formula is the nitrogen fertilizer cost C fertilizer : M f =C fertilizer (t) = P N (t)×N applied Among them, C fertilizer is the dynamic price cost of nitrogen fertilizer, which is a function of time t; Napplied is the nitrogen fertilizer application rate; further yield (t) and P N (t) Conduct dynamic analysis to evaluate the impact of price fluctuations on the results of cost-benefit analysis, apply the ARIMA model to predict nitrogen fertilizer prices, use the exponential smoothing model to predict crop prices, and define the nitrogen fertilizer price prediction function as follows: P N (t)=ARIMA(p,d,q)(X t ) Among them, X t is the historical price time series of nitrogen fertilizer; p, d, q are the parameters of the ARIMA model, where p represents the order of the autoregressive term, d represents the number of differences, and q represents the order of the moving average term; t represents time; The updated nitrogen fertilizer cost calculation formula is as follows: M f =C fertilizer (t) = P N (t)×N applied =ARIMA(p,d,q)(X t )×N applied Thus, the fertilizer cost M of the crop is determined f function.

[0009] As described above, in a comprehensive benefit evaluation method for nitrogen fertilizer application based on CBA cost-benefit analysis, in step S6, four economic evaluation indicators are introduced, namely, treatment cost, damage loss, replacement cost and reduction loss, and the quantified environmental cost is the marginal environmental loss M of the ammonia volatilization acid rain effect caused by nitrogen application. (NH3) The marginal environmental loss M of total nitrogen eutrophication due to runoff and leaching and the average release of carbon dioxide M (N2O) Three categories, calculate the environmental cost M of crops e ; The marginal environmental loss of ammonia volatilization acid rain effect caused by nitrogen application is calculated as: M (NH3) =1.88×F NH3 (Nrate)×P a ×17 / 14 Among them, F NH3 (Nrate) is the amount of ammonia volatilization produced by nitrogen application, P a Expressed as per 1 kg SO 2 The economic losses that will be caused; and the marginal environmental losses caused by the ammonia volatilization acid rain effect of nitrogen application under different crop varieties are calculated; The marginal environmental loss of total nitrogen eutrophication effect from runoff and leaching is expressed as follows: M=[0.42×(F LTN (Nrate)+F RTN (Nrate))+0.33×F HN3 (Nrate)×17 / 14]×P e Among them, F LTN (Nrate) is the leaching loss caused by nitrogen application, F RTN (Nrate) is the runoff loss caused by nitrogen application, P e Indicates per kilogram and calculate the marginal environmental losses of total nitrogen eutrophication effects from runoff and leaching under different crop varieties; Based on the carbon dioxide price monitoring data, the average market price of carbon dioxide is calculated under different crop varieties.

[0010] As described above, in a method for evaluating the comprehensive benefit of nitrogen fertilizer application based on CBA cost-benefit analysis, in step S8, the comprehensive benefit of nitrogen fertilizer N is calculated by the following formula: xe ; N xe =M ra (F a (N),P ar )-M f (N ar ,P f )-∑M e (F e (N),P e ) The marginal output benefit is obtained by taking the first-order derivative of the output benefit, the marginal output is obtained by taking the first-order derivative of the output, and the marginal loss environmental benefit cost of nitrogen fertilizer is combined with the environmental benefit part.

[0011] In the above-mentioned comprehensive benefit evaluation method of nitrogen fertilizer application based on CBA cost-benefit analysis, in step S8, the net present value calculation formula is as follows: NPV=RC Among them, NPV is net present value, R is total revenue, and C is total cost; The benefit-cost ratio is calculated as follows: BCR=R / C Among them, BCR is the cost-effectiveness ratio; By adding the time parameter, the net present value and benefit-cost ratio are made dynamic over time, and the updated calculation formula is as follows: NPV(t)=R(t)-C(t) BCR(t)=R(t) / C(t).

[0012] In the above-mentioned comprehensive benefit evaluation method of nitrogen fertilizer application based on CBA cost-benefit analysis, in step S9, the yield loss is calculated by the following formula: Production loss = output × production reduction ratio The economic loss is calculated using the following formula: Economic loss = loss of production × 1000 × purchase price.

[0013] In the above-mentioned comprehensive benefit evaluation method of nitrogen fertilizer application based on CBA cost-benefit analysis, in step S10, uncertainty analysis is performed on the CBA cost-benefit analysis model: the sources of uncertainty are identified, the uncertainty is quantified, the range of values ​​of uncertain parameters is described using normal distribution and lognormal distribution, a large number of parameter combinations are randomly generated through Monte Carlo simulation method, and the model output under each combination is calculated to evaluate the distribution of the output; A sensitivity analysis was conducted on the CBA cost-benefit analysis model: a single-factor sensitivity analysis was conducted by changing one of the input parameters, including crop type, nitrogen fertilizer price, and market price of each type of crop; a multi-factor sensitivity analysis was conducted by changing multiple input parameters, including crop type, nitrogen fertilizer price, and market price of each type of crop. The elasticity of the model output for each input parameter, namely, the ratio of the percentage change in the output to the percentage change in the input parameter, was calculated for elasticity analysis.

[0014] The beneficial effects of the present invention are: In the present invention, the method of automatically monitoring data and establishing a comprehensive benefit evaluation model replaces the method of obtaining data through manual field experiments, eliminates the uncertainty factors of manual benefit evaluation, comprehensively considers the positive economic feedback brought by crop yield and the negative economic feedback brought by environmental pollution, and presents the benefit indicators in RMB. While improving the availability and accuracy of data, it comprehensively considers positive and environmental factors, greatly saves labor, and avoids unnecessary economic losses and environmental damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0016] The present embodiment provides a method for evaluating the comprehensive benefit of nitrogen fertilizer application based on CBA cost-benefit analysis, which includes the following steps: determining evaluation targets and identifying costs and benefits; collecting basic data such as crop types, nitrogen fertilizer prices, and crop prices; establishing a CBA (Cost-Benefit Analysis) cost-benefit analysis model; determining the marginal yield benefit of crops, predicting crop price changes using an exponential smoothing model, predicting results using a machine model, and determining the relationship between crop yield and nitrogen application amount; determining fertilizer costs, and predicting fertilizer prices using an ARIMA model (autoregressive integrated moving average model); quantifying environmental costs and calculating environmental pollution control costs; calculating the comprehensive benefits of nitrogen fertilizers; calculating net present value (NPV) and benefit-cost ratio (BCR); calculating yield reduction losses and economic losses, and comprehensively calculating net losses; and performing uncertainty analysis and sensitivity analysis.

[0017] Identify costs and benefits, specifically including: identifying direct costs and indirect costs of nitrogen fertilizer application, the direct costs of nitrogen fertilizer application include the purchase and application costs of nitrogen fertilizer, the indirect costs of nitrogen fertilizer application include environmental loss costs, the environmental loss costs include acid rain effect losses, greenhouse effect losses and eutrophication effect losses; the benefits are divided into direct benefits and indirect benefits, the direct benefits of nitrogen fertilizer application are the income brought about by increased crop yields, and the indirect benefits of nitrogen fertilizer application are the social benefits brought about by environmental improvements.

[0018] Establishing the CBA cost-benefit analysis model specifically includes: using marginal analysis to evaluate the marginal output brought about by each additional unit of nitrogen fertilizer input, and determining the marginal output benefit of the crop; using the exponential smoothing model to predict crop price changes, using the machine model to predict results, determining the relationship between crop yield and nitrogen application amount, and using the ARIMA model to predict fertilizer prices; quantifying the environmental cost and calculating the cost of environmental pollution control; calculating the comprehensive benefits of nitrogen fertilizer, calculating the net present value NPV and the benefit-cost ratio BCR, calculating the loss of production reduction and economic loss, comprehensively calculating the net loss, and conducting uncertainty analysis and sensitivity analysis.

[0019] Determine the marginal yield of crops, use exponential smoothing models to predict crop price changes, use machine models to predict results, and determine the relationship between crop yield and nitrogen application, including: By collecting data for analysis, a functional relationship between yield and nitrogen application rate is established, and the marginal yield is calculated using the additional yield brought by each additional unit of nitrogen fertilizer. The marginal yield is multiplied by the market price of the crop to obtain the marginal yield benefit; After determining the marginal yield benefit of the crop, the exponential smoothing model is used to predict crop price changes. The exponential smoothing model is a time series prediction method that is suitable for situations where data has trends or seasonal patterns. Based on the basic data collection, multiple smoothing parameters and initial smoothing values ​​are determined, and the exponential smoothing formula is applied for iterative calculations. The last smoothed value is used as the predicted value for future time points. The exponential smoothing model is used to predict crop price changes, the CBA cost-benefit analysis model calculation formula is updated, and the machine model is used to determine the relationship function between crop yield and nitrogen fertilizer application to determine the direct benefit.

[0020] Determine the fertilizer cost and use the ARIMA model to predict the fertilizer price, specifically including: according to the basic data of nitrogen fertilizer price, use the autocorrelation function and the partial autocorrelation function graph to determine the parameters of the ARIMA model, including the order p of the autoregressive term, the number of differences d, and the order q of the moving average term, use the selected p, d and q parameters to establish the ARIMA model, and estimate the nitrogen fertilizer application price.

[0021] Quantifying environmental costs specifically includes: quantifying environmental loss costs, namely the indirect costs of nitrogen fertilizer application. Nitrogen fertilizer applied to farmland can be lost to the environment through various channels. Four economic evaluation indicators are introduced, namely treatment costs, damage losses, substitution costs, and reduction losses. Treatment costs refer to the economic expenditures required for governance and restoration activities that the government or enterprises need to carry out in response to environmental pollution caused by the application of nitrogen fertilizers, including the construction and operation costs of wastewater treatment facilities and the costs of ecological restoration projects; damage losses refer to the losses of ecosystems and natural resources caused by environmental pollution; substitution costs refer to the economic expenditures for taking other alternative methods due to environmental pollution caused by the application of nitrogen fertilizers; reduction losses refer to the economic losses that farmers may face due to reducing the use of nitrogen fertilizers, including market price fluctuations; the three indicators of economic losses, eutrophication losses, and market prices are used to measure the costs of environmental pollution control.

[0022] The calculation of the comprehensive benefit of nitrogen fertilizer, the calculation of the net present value NPV and the benefit-cost ratio BCR specifically include: obtaining direct benefits by integrating the marginal yield benefits of the crops, obtaining the direct costs by predicting the fertilizer prices by the ARIMA model, obtaining indirect costs by evaluating the environmental pollution control costs by the four economic evaluation indicators, calculating the comprehensive benefit of nitrogen fertilizer by using the CBA cost-benefit analysis model formula, calculating the net present value NPV, quantifying the expected cash inflows and outflows of nitrogen fertilizer application in the entire cycle discounted to the current sum, calculating the benefit-cost ratio BCR, an indicator for evaluating the economic benefits of nitrogen fertilizer application, representing the ratio of the benefits generated by the nitrogen fertilizer application process to its costs; the calculation of the reduction in production losses specifically includes: evaluating the reduction in production losses when the crop yield is lower than the expected maximum yield, and quantifying the reduction in production losses by using the yield reduction ratio and the maximum yield through a formula.

[0023] like Figure 1 As shown, a comprehensive benefit evaluation method for nitrogen fertilizer application based on CBA cost-benefit analysis includes the following steps: S1. Determine the evaluation objectives and identify the costs and benefits of nitrogen fertilizer application.

[0024] The cost of nitrogen fertilizer application includes direct cost and indirect cost. The direct cost is the purchase and application cost of nitrogen fertilizer. f , the indirect cost is the environmental loss control cost M e ; The benefits include direct benefits and indirect benefits. The direct benefits are the income brought by the increase in crop yields, that is, the crop yield benefits M ra , the indirect benefits are the social benefits brought about by environmental improvement.

[0025] Quantify crop yield benefits M ra (F a (N),P ar ) is influenced by the marginal product F a (N) and wheat price P ar , quantify the purchase and application costs of nitrogen fertilizer M f (N ar ,P f ) is influenced by the fertilizer price P f and nitrogen application rate N ar , quantify the cost of environmental loss governance ∑M e (F e (N),P e ) is the environmental effect loss equivalent F e (N) and the environmental cost of this effect P e function.

[0026] S2. Collect basic data, including crop types, nitrogen fertilizer prices, and crop prices; In order to efficiently obtain basic data such as crop types, nitrogen fertilizer prices, crop prices, etc., an automated and systematic data collection process is implemented by calling the server; this process will clarify the type of data that needs to be collected, covering key information such as different crop types, nitrogen fertilizer prices, and market prices of various types of crops; a detailed data collection plan will be formulated, which will include data sources, collection frequency, data format, and expected data volume; using advanced network technology and scripts, a set of automated data crawling tools will be developed, which will regularly extract the required data from designated servers or databases; after collecting the data, the data will be strictly verified to ensure its accuracy and reliability, and the necessary data cleaning process will be performed to eliminate erroneous or incomplete data records.

[0027] In addition, a centralized data storage system, such as a relational database, will be built to store, manage and retrieve the collected data; in order to ensure that the information in the database can reflect the latest market trends, a data update mechanism will also be designed and implemented.

[0028] S3. After determining the crop benefits and costs, a CBA cost-benefit analysis model is established to calculate the net benefits of nitrogen fertilizer.

[0029] After completing the data collection, all the collected costs and benefits were quantified, and the non-monetary benefits were converted into quantifiable amounts for comparison. After the quantification was completed, the CBA cost-benefit analysis model calculation formula was initially established to calculate the comprehensive benefits of nitrogen fertilizer (N xe ), the present value method is used to discount future cash flows in order to compare costs and benefits at different points in time; on this basis, the cost-effectiveness ratio can be calculated, that is, the ratio of the total benefits of the project to the total costs.

[0030] According to the following formula, the nitrogen fertilizer cost and environmental cost are deducted from the nitrogen fertilizer output benefit, and the first-order derivative of the nitrogen fertilizer net benefit function is calculated. When the first-order derivative is 0, the maximum net benefit and the recommended fertilizer application amount are obtained.

[0031] Comprehensive benefits of nitrogen fertilizer: N xe =M ra (F a (N),P ar )-M f (N ar ,P f )-∑M e (F e (N),P e ) Among them, M ra is the marginal yield benefit of crops (yuan / hm2 2 ), is the marginal product (F a (N)(kg / hm 2 )) and crop price P ar (yuan / kg); M f is the fertilizer cost (yuan / hm 2 ), is the fertilizer price P f (yuan / kg) and nitrogen application rate N (kg / hm 2 ) function; M e is the environmental cost of marginal loss of nitrogen fertilizer (yuan / hm2 2 ), is the environmental effect loss equivalent F e (N) and the environmental cost of this effect P e (Yuan / kg) function.

[0032] S4. Determine the marginal yield of crops, use exponential smoothing models to predict changes in crop prices, use machine models to predict results, and determine the relationship between crop yield and nitrogen application.

[0033] Marginal analysis is used to evaluate the marginal yield brought by each additional unit of nitrogen fertilizer input. The marginal yield is multiplied by the market price of the crop to determine the marginal yield benefit of the crop. A functional relationship between yield and nitrogen application is established, and the marginal yield benefit is obtained as yield benefit R yield .

[0034] Quantify the dynamics of crop market purchase price, assuming that the crop purchase price is =P yield (t), where t represents time, we get the function expression P yield (t)=f 1 (t), where f 1 (t) is a price function that changes over time; quantify the dynamics of nitrogen fertilizer prices, and assume that the nitrogen fertilizer price is P N (t), obtain the function expression P N (t)=f 2 (t), where f 2 (t) is a price function that changes over time, and t represents time; the dynamic price benefit R in the model and formula is the output benefit R yield : R yield =P yield ×(Y max -Y base ) Among them, P yield is the crop market price, Y max is the maximum yield (kg / hm 2 ), Y base is the basic yield (kg / hm 2 ).

[0035] Quantify the dynamics of crop market purchase prices and nitrogen fertilizer prices to obtain dynamic price benefits R yield (t): R yield (t) = P yield (t)×(Y max -Y base ) Apply the exponential smoothing formula for iterative calculation to predict crop price changes, determine the relationship function between crop yield, marginal yield and crop price, and determine the marginal yield benefit M of the crop. ra .

[0036] Using the exponential smoothing model, multiple smoothing parameters and initial smoothing values ​​are determined, the exponential smoothing formula is applied for iterative calculation, the last smoothing value is used as the predicted value at a future time point, the exponential smoothing model is used to predict crop price changes, the CBA cost-benefit analysis model calculation formula is updated, and the relationship function between crop yield and nitrogen fertilizer application is determined using the machine model to determine the direct benefit; the general form of the exponential smoothing model is expressed as: in, is the predicted value at the next time point; t is the actual observed value at the current time point; is the predicted value at the current time point; α is a smoothing parameter whose value is between 0 and 1 and is used to balance the importance of historical data and recent observations.

[0037] For the exponential smoothing model with trend (Holt linear trend model), it is expressed as: Among them, l t is the level term at time t (long-term trend); b t is the trend term (slope) at time t; l t+1 =α(y t -b t )+(1-α)(l t +b t ) b t+1 =β(l t+1 -l t )+(1-β)b t Among them, α is the smoothing parameter of the level; β is the smoothing parameter of the trend.

[0038] For an exponential smoothing model with a seasonal pattern (Holt-Winters seasonal model), it is expressed as: where h is the length of the seasonal cycle; s is the position within the seasonal cycle; s t is the seasonal term at time t.

[0039] The updated exponential smoothing model equation is: l t+1 =α(y t -s t )+(1-α)(l t +b t ) b t+1 =β(lt+1 -l t )+(1-β)b t s t+1 =γ(y t -l t -b t )+(1-γ)s t Here, γ is the seasonal smoothing parameter.

[0040] Define a price-time function and define an exponential smoothing model with a seasonal pattern for the crop purchase price. The price-time function is defined as follows: Among them, P yield (t) is the predicted value of the crop purchase price at time t; l t is the horizontal term at time t; b t is the trend term at time t; s t is the seasonal term at time t; h is the length of the seasonal cycle; is the current time's position within the seasonal cycle.

[0041] In summary, the cost-effectiveness formula of nitrogen fertilizer application under the CBA cost-effectiveness model is updated to obtain the crop yield benefit, that is, the direct benefit of nitrogen fertilizer application: S5. Determine the fertilizer cost and use the ARIMA model to predict the fertilizer price.

[0042] Predict the dynamics of crop market purchase price, assuming the crop purchase price is P yield (t), P yield (t)=f 1 (t), f 1 (t) is a price function that changes over time; To predict the dynamic price of nitrogen fertilizer, let the price of nitrogen fertilizer be P N (t), P N (t)=f 2 (t), f 2 (t) is a time-varying function of price.

[0043] The dynamic price cost in the model and formula is the nitrogen fertilizer cost C fertilizer : M f =C fertilizer (t) = P N (t)×N applied Further on P yield (t) and P N(t) Conduct dynamic analysis to evaluate the impact of price fluctuations on the results of cost-benefit analysis, apply the ARIMA model to predict nitrogen fertilizer prices, use the exponential smoothing model to predict crop prices, and define the nitrogen fertilizer price prediction function as follows: P N (t)=ARIMA(p,d,q)(X t ) Among them, X t is the historical price time series of nitrogen fertilizer; p, d, q are the parameters of the ARIMA model, where p represents the order of the autoregressive term, d represents the number of differences, q represents the order of the moving average term; t represents time.

[0044] The updated nitrogen fertilizer cost calculation formula is as follows: M f =C fertilizer (t) = P N (t)×N applied =ARIMA(p,d,q)(X t )×N applied The mean error of the predicted price of the crops and the price variation range of the crops can be obtained. It can be seen that the mean error of the predicted price of wheat is 20.763, the mean error of the predicted price of corn is 12.539, the price variation range of wheat is (-20.763, +20.763), and the price variation range of corn is (-12.539—+12.539); due to data acquisition reasons, the temporary variation range of nitrogen fertilizer prices is (-250.1089, 250.1089).

[0045] S6. Quantify environmental costs and calculate the costs of environmental pollution control.

[0046] Nitrogen fertilizer applied to farmland can be lost to the environment through various pathways, such as the loss of N 2 O. Ammonia volatilization, nitrate nitrogen and ammonia nitrogen have different effects on the environment and can cause chain reactions in the environment. Therefore, it is difficult to evaluate their comprehensive effects with a unified indicator.

[0047] Four economic evaluation indicators are introduced, namely treatment cost, damage loss, replacement cost and reduction loss. The environmental cost is quantified as the marginal environmental loss M (NH 3 ), marginal environmental loss of total nitrogen eutrophication due to runoff and leaching, and average release of carbon dioxide, M (N 2 O) Three categories, calculate the environmental cost of crops M e .

[0048] N 2 O emissions, N leaching, runoff, and NH3 The average volatilization losses were 1.84, 18.4, 9.9 and 25.2 kgN / ha, with loss rates of 1.0%, 8.9%, 5.7% and 14.0%, respectively. According to the Eco-indicator95 conversion procedure, 1 kgNH 3 Volatilization is equivalent to 0.33kg Eutrophication effect and 1.88kgSO 2 Acid rain effect; 1kg of TN lost in runoff or leaching is equivalent to 0.42kg Eutrophication effect; 1kgN 2 O is equivalent to 310 kg CO on a 100-year scale 2 greenhouse gas effect.

[0049] According to the research results of the Chinese Academy of Environmental Sciences and Tsinghua University, the losses caused by acid rain pollution to my country exceed 110 billion yuan per year, that is, every kg of SO2 is discharged. 2 Will cause a loss of more than 5 yuan; the marginal environmental loss of ammonia volatilization acid rain effect caused by nitrogen application is calculated as: M( NH3 )=1.88×F NH3 (Nrate)×P a ×17 / 14 The marginal environmental loss of ammonia volatilization acid rain effect caused by nitrogen application was calculated under different crop varieties; a Expressed as per 1kg SO 2 The economic loss will be caused, in yuan / kg -1 .

[0050] Studies have shown that the environmental loss of activated nitrogen in water bodies to fisheries, drinking water sources, tourism and living environment is about 0.41 yuan / kg. -1 / N, according to the "Standards and Calculation Methods for Sewage Discharge Fees", every 0.25kg of total phosphorus is equivalent to 1kg of pollution equivalent value, and the calculation formula can be used to quantify the cost: Sewage discharge fee = 0.7 yuan × the pollution equivalent number of pollutants; the cost of treating these wastewaters is 2.8 yuan / kg / The total converted into eutrophication loss is equivalent to 3.0 yuan / kg / ; Therefore, the marginal environmental loss of total nitrogen eutrophication effect from runoff and leaching is expressed as follows: M=[0.42×(F LTN (Nrate)+F RTN (Nrate))+0.33×F HN3 (Nrate)×17 / 14]×P e The marginal environmental loss of total nitrogen eutrophication effect of runoff and leaching was calculated under different crop varieties; e Expressed as per kg Eutrophication loss, unit is yuan / kg -1 .

[0051] N 2 O is an important greenhouse gas, with a 2 The greenhouse effect of O is equivalent to 310 kg CO over a 100-year time scale. 2 According to the CO2 price monitoring data, from July 25, 2024 to August 23, 2021, the average price of CO2 in the mainstream market nationwide is 327.9 yuan / ton; the average market price of CO2 is calculated under different crop varieties, where Pgh is the international CO2 2 The market price, unit: kg -1 .

[0052] In summary, for the environmental pollution control cost of applying nitrogen fertilizer, taking crops such as rice, corn and wheat as examples, the data in Table 1 below are calculated.

[0053] Table 1

[0054] In Table 1, Pa is expressed as per 1kg SO 2 The economic loss will be caused, in yuan / kg -1 ; Pe means per kg Eutrophication loss, unit is yuan / kg -1 ; Pgh represents the international CO 2 The market price, in yuan / kg -1 .

[0055] S7. Calculate the comprehensive benefit of nitrogen fertilizer N by the following formula xe ; N xe =M ra (F a (N),P ar )-M f (N ar ,P f )-∑M e (F e (N),P e ) The marginal output benefit is obtained by taking the first-order derivative of the output benefit, the marginal output is obtained by taking the first-order derivative of the output, and the marginal loss environmental benefit cost of nitrogen fertilizer is combined with the environmental benefit part.

[0056] S8. Calculate the net present value and benefit-cost ratio; NPV=RC Among them, NPV is net present value, R is total revenue, and C is total cost; The benefit-cost ratio is calculated as follows: BCR=R / C By adding the time parameter, the net present value and benefit-cost ratio are made dynamic over time, and the updated calculation formula is as follows: NPV(t)=R(t)-C(t) BCR(t)=R(t) / C(t).

[0057] S9. Calculate the loss of production reduction and economic losses and calculate the net loss comprehensively; The loss of production reduction is calculated by the following formula: Yield loss (tons / hectare) = yield × yield reduction ratio The economic loss is calculated using the following formula: Economic loss (yuan / hectare) = production loss (tons / hectare) × 1000kg / t × purchase price (yuan / kg).

[0058] S10. Conduct uncertainty analysis and sensitivity analysis.

[0059] Uncertainty analysis of the CBA cost-benefit analysis model was conducted: the sources of uncertainty were identified, the uncertainty was quantified, the range of values ​​of uncertain parameters was described using normal distribution and lognormal distribution, a large number of parameter combinations were randomly generated through the Monte Carlo simulation method, and the model output under each combination was calculated to evaluate the distribution of the output.

[0060] A sensitivity analysis was conducted on the CBA cost-benefit analysis model: a single-factor sensitivity analysis was conducted by changing one of the input parameters, including crop type, nitrogen fertilizer price, and market price of each type of crop; a multi-factor sensitivity analysis was conducted by changing multiple input parameters, including crop type, nitrogen fertilizer price, and market price of each type of crop. The elasticity of the model output for each input parameter, namely, the ratio of the percentage change in the output to the percentage change in the input parameter, was calculated for elasticity analysis.

[0061] The method of this embodiment adopts automatic monitoring data and the establishment of a comprehensive benefit evaluation model instead of obtaining data through manual field experiments, eliminating the uncertainty factors of manual benefit evaluation, comprehensively considering the positive economic feedback brought by crop yield and the negative economic feedback brought by environmental pollution, and presenting benefit indicators in RMB. While improving the availability and accuracy of data, it comprehensively considers positive and environmental factors, greatly saves labor, and avoids unnecessary economic losses and environmental damage.

[0062] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A comprehensive benefit evaluation method for nitrogen fertilizer application based on CBA cost-benefit analysis, characterized in that: The following steps are involved: S1. Determine the evaluation objectives and identify the costs and benefits of nitrogen fertilizer application; S2. Collect basic data, including crop types, nitrogen fertilizer prices, and crop prices; S3. Establish a CBA cost-benefit analysis model; S4. Determine the marginal yield of crops, use exponential smoothing models to predict crop price changes, use machine models to predict results, and determine the relationship between crop yield and nitrogen application; S5. Determine fertilizer cost and use ARIMA model to predict fertilizer price; S6. Quantify environmental costs and calculate the cost of environmental pollution control; S7. Calculate the comprehensive benefits of nitrogen fertilizer; S8. Calculate the net present value and benefit-cost ratio; S9. Calculate the loss of production reduction and economic losses and calculate the net loss comprehensively; S10. Conduct uncertainty analysis and sensitivity analysis.

2. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 1, characterized in that: In step S1, the cost of nitrogen fertilizer application includes direct cost and indirect cost. The direct cost is the purchase and application cost of nitrogen fertilizer. f , the indirect cost is the environmental loss control cost M e ; The benefits include direct benefits and indirect benefits. The direct benefits are the income brought by the increase in crop yields, that is, the crop yield benefits M ra , indirect benefits are social benefits brought about by environmental improvement; Quantify crop yield benefits M ra (F a (N),P ar ) is influenced by the marginal product F a (N) and wheat price P ar , quantify the purchase and application costs of nitrogen fertilizer M f (N ar ,P f ) is influenced by the fertilizer price P f and nitrogen application rate N ar , quantify the cost of environmental loss governance ∑M e (F e (N),P e ) is the environmental effect loss equivalent F e (N) and the environmental cost of this effect P e function.

3. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 2, characterized in that: In step S3, a CBA cost-benefit analysis model is established to calculate the net benefit of nitrogen fertilizer, and the nitrogen fertilizer cost and environmental cost are deducted from the yield benefit of nitrogen fertilizer according to the following formula: N xe =M ra (F a (N),P ar )-M f (N ar ,P f )-∑M e (F e (N),P e ) Among them, M ra is the marginal output benefit of the crop, which is the marginal output F a (N) and crop price P ar Function of M f is the fertilizer cost, is the fertilizer price P f Function of nitrogen application rate N; M e is the environmental cost of the marginal loss of nitrogen fertilizer, and is the environmental loss equivalent F e (N) and the environmental cost of this effect P e function.

4. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 3, characterized in that: In step S4, marginal analysis is used to evaluate the marginal yield brought by each additional unit of nitrogen fertilizer input to determine the marginal yield benefit of crops; a functional relationship between yield and nitrogen application rate is established to obtain the marginal yield benefit as yield benefit R yield : R yield =P yield ×(Y max -Y base ) Among them, P yield is the crop market price, Y max is the maximum output, Y base is the base output; Quantify the dynamics of crop market purchase prices and nitrogen fertilizer prices to obtain dynamic price benefits R yield (t): R yield (t)=P yield (t)×(Y max -Y base ) Apply the exponential smoothing formula for iterative calculation to predict crop price changes, determine the relationship function between crop yield, marginal yield and crop price, and determine the marginal yield benefit M of the crop. ra .

5. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 4, characterized in that: In step S5, the crop market purchase price is predicted to be dynamic, and the crop purchase price is set to P yield (t), P yield (t)=f1(t), f1(t) is a price function that changes over time; to predict the dynamic price of nitrogen fertilizer, let the price of nitrogen fertilizer be P N (t), P N (t)=f2(t), f2(t) is the price function that changes over time; The dynamic price cost in the model and formula is the nitrogen fertilizer cost C fertilizer : M f =C fertilizer (t)=P N (t)×N applied Among them, C fertilizer is the dynamic price cost of nitrogen fertilizer, which is a function of time t; N applied is the nitrogen fertilizer application rate; further yield (t) and P N (t) Conduct dynamic analysis to evaluate the impact of price fluctuations on the results of cost-benefit analysis, apply the ARIMA model to predict nitrogen fertilizer prices, use the exponential smoothing model to predict crop prices, and define the nitrogen fertilizer price prediction function as follows: P N (t)=ARIMA(p,d,q)(X t ) Among them, X t is the historical price time series of nitrogen fertilizer; p, d, q are the parameters of the ARIMA model, where p represents the order of the autoregressive term, d represents the number of differences, and q represents the order of the moving average term; t represents time; The updated nitrogen fertilizer cost calculation formula is as follows: M f =C fertilizer (t)=P N (t)×N applied =ARIMA(p,d,q)(X t )×N applied Thus, the fertilizer cost M of the crop is determined f function.

6. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 5, characterized in that: In step S6, four economic evaluation indicators are introduced, namely, treatment cost, damage loss, replacement cost and reduction loss. The quantified environmental cost is the marginal environmental loss M of the ammonia volatilization acid rain effect caused by nitrogen application. (NH3) The marginal environmental loss M of total nitrogen eutrophication due to runoff and leaching and the average release of carbon dioxide M (N2O) Three categories, calculate the environmental cost M of crops e ; The marginal environmental loss of ammonia volatilization acid rain effect caused by nitrogen application is calculated as: I (NH3) =1.88×F NH3 (Nrate)×P a ×17 / 14 Among them, F NH3 (Nrate) is the amount of ammonia volatilization produced by nitrogen application, P a Expressed as the economic loss caused by each kg of SO2 emitted; and calculated the marginal environmental loss of the ammonia volatilization acid rain effect caused by nitrogen application under different crop varieties; The marginal environmental loss of total nitrogen eutrophication effect from runoff and leaching is expressed as follows: M=[0.42×(F LTN (Nrate)+F RTN (Nrate))+0.33×F HN3 (Nrate)×17 / 14]×P e Among them, F LTN (Nrate) is the leaching loss caused by nitrogen application, F RTN (Nrate) is the runoff loss caused by nitrogen application, P e Indicates per kilogram and calculate the marginal environmental losses of total nitrogen eutrophication effects from runoff and leaching under different crop varieties; Based on the carbon dioxide price monitoring data, the average market price of carbon dioxide is calculated under different crop varieties.

7. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 6, characterized in that: In step S8, the comprehensive benefit of nitrogen fertilizer N is calculated by the following formula: xe ; N xe =M ra (F a (N),P ar )-M f (N ar ,P f )-∑M e (F e (N),P e ) The marginal output benefit is obtained by taking the first-order derivative of the output benefit, the marginal output is obtained by taking the first-order derivative of the output, and the marginal loss environmental benefit cost of nitrogen fertilizer is combined with the environmental benefit part.

8. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 7, characterized in that: In step S8, the net present value calculation formula is as follows: NPV=RC Among them, NPV is net present value, R is total revenue, and C is total cost; The benefit-cost ratio is calculated as follows: BCR=R / C Among them, BCR is the cost-effectiveness ratio; By adding the time parameter, the net present value and benefit-cost ratio are made dynamic over time, and the updated calculation formula is as follows: NPV(t)=R(t)-C(t) BCR(t)=R(t) / C(t).

9. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 8, characterized in that: In step S9, the production loss is calculated by the following formula: Production loss = output × production reduction ratio The economic loss is calculated using the following formula: Economic loss = loss of production × 1000 × purchase price.

10. The method for comprehensive benefit evaluation of nitrogen fertilizer application based on CBA cost-benefit analysis according to claim 9, characterized in that: In step S10, uncertainty analysis is performed on the CBA cost-benefit analysis model: the sources of uncertainty are identified, the uncertainty is quantified, the range of values ​​of uncertain parameters is described using normal distribution and lognormal distribution, a large number of parameter combinations are randomly generated through Monte Carlo simulation method, and the model output under each combination is calculated to evaluate the distribution of the output; A sensitivity analysis was conducted on the CBA cost-benefit analysis model: a single-factor sensitivity analysis was conducted by changing one of the input parameters, including crop type, nitrogen fertilizer price, and market price of each type of crop; a multi-factor sensitivity analysis was conducted by changing multiple input parameters, including crop type, nitrogen fertilizer price, and market price of each type of crop. The elasticity of the model output for each input parameter, namely, the ratio of the percentage change in the output to the percentage change in the input parameter, was calculated for elasticity analysis.

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