A method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand

Abstract

The present invention relates to the field of agricultural technology, and in particular to a method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand. The present invention divides the area to be tested into multiple areas according to soil type and type of planted crops, and divides each area into multiple sub-areas. Each sub-area returns manure to the field in different proportions, and performs polynomial approximation regression analysis on the soil carbon fixation rate and the proportion of manure to fertilizer in different sub-areas, and fits to obtain the response relationship between the soil carbon fixation rate and the proportion of manure to fertilizer, and uses the fitting formula to calculate the proportion of manure to fertilizer when the soil carbon fixation rate is the largest; the manure nitrogen demand of the area to be tested is calculated using the obtained proportion of manure to fertilizer, and then the annual fertilizer application amount is determined. The method provided by the present invention can minimize the amount of fertilizer while maximizing the soil carbon fixation rate, and can promote the sustainability of agricultural production, improve resource utilization efficiency, and reduce greenhouse gas emissions.

Description

Technical Field

[0001] The present invention relates to the field of agricultural technology, and in particular to a method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand. Background Art

[0002] With the rapid development of modern agriculture, soil nutrient management and carbon sequestration technology have become the key to sustainable agricultural development. Reasonable replenishment of soil nutrients can not only increase crop yields, but also improve soil structure and environment. At the same time, soil carbon sequestration, as an important means of mitigating climate change, has received increasing attention. However, how to maximize the soil carbon sequestration rate while meeting crop nutrient requirements and minimizing the amount of fertilizer is a technical problem that needs to be solved urgently.

[0003] At present, soil nutrient management mainly relies on the application of chemical fertilizers and organic fertilizers. Although chemical fertilizers are effective quickly, long-term use can lead to soil acidification, compaction and other problems. Organic fertilizers, especially manure, are gradually becoming an important choice for soil nutrient management because they contain rich organic matter and slow-release nutrients. However, there is no unified standard for the proportion and method of manure application, and there is no systematic study on its effect on soil carbon sequestration.

[0004] Traditional fertilization methods are mainly based on the nutrient requirements of crops, ignoring the effect of soil carbon sequestration. How to increase the soil carbon sequestration rate through the rational application of manure and minimize the amount of fertilizer while ensuring the nutrient requirements of crops is a challenge facing the current agricultural technology field. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand. The method provided by the present invention is a comprehensive optimization model of soil nutrient demand and carbon fixation effect based on manure return to the field, which can determine the optimal proportion and application amount of manure, which can maximize the soil carbon fixation rate and minimize the amount of fertilizer. In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand, comprising the following steps:

[0007] 1) Divide the area to be regulated into different test areas according to soil type and crop type, and each test area has only one soil type and one crop; each test area is processed in steps 2) to 7);

[0008] 2) Divide the area to be tested into 10 to 20 sub-areas, return manure to the fields at different proportions in each sub-area, and obtain sub-areas with different proportions of manure to fertilizer application;

[0009] 3) The soil carbon fixation rate after returning manure to the fields in different sub-regions was determined, and the soil carbon fixation rate and the proportion of manure to fertilizer in different sub-regions were subjected to polynomial approximation regression analysis to fit the response relationship between the soil carbon fixation rate and the proportion of manure to fertilizer, as shown in Formula I:

[0010] Formula I;

[0011] In formula I, V is the soil carbon fixation rate, in kg / hm 2 a; E is the proportion of manure to fertilizer, unit is %; a1, a2 and c are constants, n is an integer, and n≥1;

[0012] The proportion of manure to fertilizer is calculated according to formula II:

[0013] E=A / B×100% Formula II;

[0014] In formula II, E is the proportion of manure to fertilizer, in units of %; A is the total nitrogen content in manure applied to the soil, in units of kg; B is the total nitrogen content in fertilizer applied to the soil, in units of kg; the fertilizer includes manure and chemical fertilizer;

[0015] 4) Calculate the multiple determination coefficient and root mean square error for different values ​​of n in formula I, select formula I corresponding to the value of n when the multiple determination coefficient is close to 1 and the root mean square error is close to 0, and obtain the fitting formula for soil carbon fixation rate and the proportion of manure in fertilizer application;

[0016] 5) Using the fitting formula, the proportion of manure to fertilizer applied when the soil carbon fixation rate is the maximum is calculated to obtain a first proportion of manure to fertilizer applied;

[0017] 6) calculating the nitrogen demand of manure in the tested area using the first manure-fertilizer ratio;

[0018] 7) Determine the annual fertilizer application amount of the tested area using the nitrogen demand of the manure, the total nitrogen content in the manure, and the proportion of the first manure in the fertilizer application.

[0019] Preferably, the soil carbon fixation rate is the annual soil carbon fixation rate when manure is returned to the fields.

[0020] Preferably, when the crop planted in the area to be tested is rice, n in Formula I=3.

[0021] Preferably, the nitrogen demand of manure in the tested area is calculated using Formula III:

[0022] Formula III;

[0023] In Formula III, Z N is the nitrogen requirement of manure in the area to be tested, in kg;

[0024] Na The annual crop yield or total area of ​​the area to be tested, in kg or hm 2 ; Artificial forest land is calculated by total area, and other crops are calculated by annual output;

[0025] N b Form 100 kg or 1m for the crops in the area to be tested 3 The nitrogen requirement for production is in kg; for artificial forest land, in 1m 3 The yield of other crops is calculated based on 100 kg yield;

[0026] X N It is the proportion of fertilizer supply determined according to the total nitrogen content of the area to be tested, in %;

[0027] E1 is the proportion of the first manure in fertilizer application, unit is %;

[0028] W N It is the utilization rate of nitrogen in manure in the current season, in %.

[0029] Preferably, different crops form 100 kg or 1m 3 The nitrogen requirements for production are as follows:

[0030]

[0031] Artificial forest land is 1m 3 The yield of other crops is calculated based on 100 kg.

[0032] Preferably, the fertilizer supply ratio determined according to the total nitrogen content of the area to be tested includes:

[0033]

[0034] The crops grown in the dry land are field crops;

[0035] The total nitrogen content of the area to be tested is the total nitrogen content measured in farmland where manure has been continuously returned to the fields for 3 years or more.

[0036] Preferably, the method for determining the total nitrogen content of the area to be tested includes: adopting a 5-point sampling method, determining the total nitrogen content of 5 sampling points, and taking the average value of the total nitrogen content of the 5 sampling points.

[0037] Preferably, soil from three tillage layers of 0-10 cm, 10-20 cm and 20-30 cm is taken from each sampling point, and the total nitrogen content is determined after the soil from the three tillage layers is mixed.

[0038] Preferably, the nitrogen utilization rate of the manure in the current season is 25% to 30%.

[0039] Preferably, the annual fertilizer application amount of the tested area in step 6) includes the annual application amount of manure and the annual application amount of chemical fertilizer, and the annual application amount of manure and the annual application amount of chemical fertilizer in the tested area are determined by formula IV and formula V respectively:

[0040] Y=Z N / X-Form IV;

[0041] In formula IV, Y is the annual amount of manure applied in the area to be tested, in kg; Z N is the nitrogen demand of manure in the tested area, in kg; X is the total nitrogen content in manure, in %;

[0042] Formula V;

[0043] In formula V, W is the annual fertilizer application amount in the tested area, in kg; Z N is the nitrogen demand of manure in the tested area, in kg; E1 is the proportion of the first manure in fertilizer application, in %; and D is the total nitrogen content in the fertilizer, in %.

[0044] Beneficial effects:

[0045] The present invention provides a method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand, comprising: dividing an area to be regulated into different test areas according to soil type and planted crop type, each test area having only one soil type and one crop; dividing the test area into 10 to 20 sub-areas, returning manure to the fields in different proportions in each sub-area, measuring the soil carbon fixation rates of different sub-areas after returning manure to the fields, performing polynomial regression analysis on the soil carbon fixation rates and the proportion of manure to fertilizer in different sub-areas, fitting to obtain a response relationship between the soil carbon fixation rate and the proportion of manure to fertilizer, and calculating the proportion of manure to fertilizer when the soil carbon fixation rate is maximum by using a fitting formula; and calculating the manure nitrogen demand of the test area by using the obtained proportion of manure to fertilizer, thereby determining the annual fertilizer application amount. The method provided by the present invention is to divide the area to be tested into sub-areas of appropriate numbers, and measure the soil carbon fixation rate under different manure-to-fertilizer ratios, and then perform polynomial regression analysis on the soil carbon fixation rate and the manure-to-fertilizer ratio. The manure-to-fertilizer ratio when the soil carbon fixation rate is maximum can be determined by using a fitting formula, and finally the manure nitrogen requirement of the area to be tested is calculated based on the obtained manure-to-fertilizer ratio, and the annual fertilizer application amount is determined. The method provided by the present invention can optimize the manure application amount and application method according to the initial nutrient status of the soil, crop demand and expected carbon fixation target; while taking into account the soil nutrient demand and carbon fixation effect, the amount of fertilizer is minimized while maximizing the soil carbon fixation rate. The method provided by the present invention can promote the sustainability of agricultural production, improve resource utilization efficiency, and reduce greenhouse gas emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0047] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0048] The present invention provides a method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand, comprising the following steps:

[0049] The area to be regulated is divided into different test areas according to soil type and planted crop type, and each test area has only one soil type and one crop; the amount of fertilizer applied when the soil carbon fixation rate of each test area is the maximum is calculated, and the calculation includes the following steps:

[0050] 1) Divide the area to be regulated into different test areas according to soil type and crop type, and each test area has only one soil type and one crop; each test area is processed in steps 2) to 7);

[0051] 2) Divide the area to be tested into 10 to 20 sub-areas, return manure to the fields at different proportions in each sub-area, and obtain sub-areas with different proportions of manure to fertilizer application;

[0052] 3) The soil carbon fixation rate after returning manure to the fields in different sub-regions was determined, and the soil carbon fixation rate and the proportion of manure to fertilizer in different sub-regions were subjected to polynomial approximation regression analysis to fit the response relationship between the soil carbon fixation rate and the proportion of manure to fertilizer, as shown in Formula I:

[0053] Formula I;

[0054] In formula I, V is the soil carbon fixation rate, in kg / hm 2 a; E is the proportion of manure to fertilizer, unit is %; a1, a2 and c are constants, n is an integer, and n≥1;

[0055] The proportion of manure to fertilizer is calculated according to formula II:

[0056] E=A / B×100% Formula II;

[0057] In formula II, E is the proportion of manure to fertilizer, in units of %; A is the total nitrogen content in manure applied to the soil, in units of kg; B is the total nitrogen content in fertilizer applied to the soil, in units of kg; the fertilizer includes manure and chemical fertilizer;

[0058] 4) Calculate the multiple determination coefficient and root mean square error for different values ​​of n in formula I, select formula I corresponding to the value of n when the multiple determination coefficient is close to 1 and the root mean square error is close to 0, and obtain the fitting formula for soil carbon fixation rate and the proportion of manure in fertilizer application;

[0059] 5) Using the fitting formula, the proportion of manure to fertilizer applied when the soil carbon fixation rate is the maximum is calculated to obtain a first proportion of manure to fertilizer applied;

[0060] 6) calculating the nitrogen demand of manure in the tested area using the first manure-fertilizer ratio;

[0061] 7) Determine the annual fertilizer application amount of the tested area using the nitrogen demand of the manure, the total nitrogen content in the manure, and the proportion of the first manure in the fertilizer application.

[0062] The present invention divides the area to be tested with the same soil type and the same crops into 10 to 20 sub-areas, preferably 15 sub-areas, and returns manure to the fields in different proportions in each sub-area to obtain sub-areas with different proportions of manure in fertilization; the area of ​​the sub-area is preferably greater than or equal to 100m 2 , more preferably 100m 2 The present invention can reduce the investment of measurement time and measurement cost on the basis of improving the accuracy of measurement results through appropriate sub-area division.

[0063] After returning manure to the field, the present invention measures the soil carbon sequestration rate after returning manure to the field in different sub-regions. In the present invention, the soil carbon sequestration rate is preferably the soil carbon sequestration rate in the year of returning manure to the field. In a specific embodiment, the present invention preferably calculates the soil carbon sequestration rate one year after returning manure to the field, and the method for determining the soil carbon sequestration rate preferably refers to the annual change in the organic carbon pool in farmland soil in the reference standard "Technical Specifications for Carbon Sequestration Accounting in Farmland Soils".

[0064] After obtaining the soil carbon fixation rate and the proportion of manure to fertilizer in different sub-regions after returning manure to the field, the present invention performs polynomial approximation regression analysis on the soil carbon fixation rate and the proportion of manure to fertilizer in different sub-regions, and fits to obtain the response relationship between the soil carbon fixation rate and the proportion of manure to fertilizer, which is specifically shown in Formula I:

[0065] Formula I;

[0066] In formula II, V is the soil carbon fixation rate, in kg / hm 2 a; E is the proportion of manure to fertilizer, unit is %; a1, a2 and c are constants, n is an integer;

[0067] The proportion of manure to fertilizer is calculated according to formula II:

[0068] E=A / B×100% Formula II;

[0069] In formula II, E is the proportion of manure to fertilizer applied, in units of %; A is the total nitrogen content in manure applied to the soil, in units of kg; B is the total nitrogen content in fertilizer applied to the soil, in units of kg; the fertilizer includes manure and chemical fertilizer.

[0070] Calculate the multiple determination coefficient and root mean square error for different values ​​of n, select formula I corresponding to the n value when the multiple determination coefficient is close to 1 and the root mean square error is close to 0, and obtain the fitting formula of soil carbon fixation rate and the proportion of manure to fertilizer. In the present invention, when the crop planted in the test area is rice, n in formula I is preferably 3.

[0071] After obtaining the fitting formula, the present invention uses the fitting formula to calculate the proportion of manure to fertilizer when the soil carbon fixation rate is maximum, and obtains the first proportion of manure to fertilizer. The soil carbon fixation rate of manure alone is lower than that of manure and chemical fertilizer. If the proportion of manure is too high, the growth rate of soil organic carbon (SOC) content will be reduced or even reach a balanced state. The fitting formula provided by the present invention has a good fitting effect, and can more accurately determine the relationship between the soil carbon fixation rate and the proportion of manure to fertilizer, so as to determine the proportion of manure to fertilizer when the soil carbon fixation rate is maximum.

[0072] After obtaining the first manure fertilizer ratio, the present invention uses the first manure fertilizer ratio to calculate the manure nitrogen demand of the measured area.

[0073] Nitrogen has a direct impact on plant growth, photosynthesis and carbon absorption. Appropriate nitrogen supply can increase plant biomass accumulation, thereby promoting soil carbon fixation. In contrast, although phosphorus is also important for plant growth, its direct relationship with soil carbon fixation is not as significant as nitrogen. In agricultural production, nitrogen is often the main limiting factor, especially in some low-nitrogen soils, where nitrogen deficiency can significantly reduce plant growth and carbon fixation capacity. Therefore, optimizing the nitrogen application ratio is more critical to improving soil carbon fixation efficiency.

[0074] In addition, phosphorus is easily fixed in the soil, especially in acidic or alkaline soils, and the effectiveness of phosphate fertilizers is often greatly affected by soil characteristics. Nitrogen is easier to lose, has a more direct regulatory effect on carbon fixation, and is easier to regulate and has a significant regulatory effect, so nitrogen is the main variable determined by the present invention. The present invention determines the optimal ratio of manure application by calculating nitrogen, which can not only meet the nutrient requirements of crops, but also maximize the soil carbon fixation rate.

[0075] In the present invention, the nitrogen demand of manure in the measured area is preferably calculated using Formula III:

[0076] Formula III;

[0077] In Formula III, Z Nis the nitrogen requirement of manure in the area to be tested, in kg;

[0078] N a The annual crop yield or total area of ​​the area to be tested, in kg or hm 2 ; Artificial forest land is calculated by total area, and other crops are calculated by annual output;

[0079] N b Form 100 kg or 1m for the crops in the area to be tested 3 The nitrogen requirement for production is in kg; for artificial forest land, in 1m 3 The yield of other crops is calculated based on 100 kg yield;

[0080] X N It is the proportion of fertilizer supply determined according to the total nitrogen content of the area to be tested, in %;

[0081] E1 is the proportion of the first manure in fertilizer application, unit is %;

[0082] W N It is the utilization rate of nitrogen in manure in the current season, in %.

[0083] In the present invention, different crops form 100 kg or 1m 3 The nitrogen requirement for production is preferably as shown in Table 1 below, specifically as follows:

[0084] Table 1 The formation of 100 kg or 1m of different crops 3 Recommended nitrogen absorption amount required for yield

[0085]

[0086] Artificial forest land is 1m 3 Yield: 3.3 kg of total nitrogen in eucalyptus in Table 1 is 1 m 3 The total nitrogen required for eucalyptus with a yield of 100 kg is 3.3 kg; the other crops are all calculated based on a yield of 100 kg.

[0087] In the present invention, the fertilizer supply ratio determined according to the total nitrogen content of the area to be tested is preferably as shown in Table 2, specifically as follows:

[0088] Table 2 Recommended values ​​of nutrient ratio of fertilizer supply under different soil nitrogen nutrient levels

[0089]

[0090] The total nitrogen content of the area to be tested is preferably the total nitrogen content measured after returning manure to the field for more than three years, and more preferably: after the crop is harvested but before sowing (preferably within 15 days after harvest), the soil organic carbon storage in the 0-30 cm tillage layer is collected and measured, and the total nitrogen content of the soil is measured at the same time; the method for measuring the total nitrogen content in the area to be tested preferably includes: using a 5-point sampling method to measure the total nitrogen content of 5 sampling points, and taking the average value of the total nitrogen content of the 5 sampling points; more preferably includes: randomly selecting 5 square blocks of fixed area with uniform growth in each sub-area according to the 5-point sampling method for sampling; each sampling point is respectively collected at 0-10 cm, 10-20 cm, and 20-30 cm tillage layers with a circular knife, and after sufficient mixing, the soil is air-dried, ground, and passed through a 60-mesh sieve to determine the total nitrogen content of each measuring point, and the average value of the 5 sampling points is taken as the total nitrogen content of the soil in the sub-area.

[0091] In the present invention, the calculation method of the seasonal utilization rate of nitrogen in manure is preferably based on the reference "Comparison of Several Typical Calculation Methods for Nitrogen Utilization Rate of Organic Fertilizer", and the seasonal utilization rate of nitrogen in manure is preferably 25% to 30%.

[0092] After obtaining the nitrogen demand of manure in the area to be tested, the present invention uses the nitrogen demand of manure, the total nitrogen content in manure and the proportion of the first manure in fertilizer application to determine the annual fertilizer application amount of the area to be tested. In the present invention, the annual fertilizer application amount of the area to be tested preferably includes the annual application amount of manure and the annual application amount of chemical fertilizer, and the annual application amount of manure and the annual application amount of chemical fertilizer in the area to be tested are preferably determined using Formula IV and Formula V:

[0093] Y=Z N / X-Form IV;

[0094] In formula IV, Y is the annual amount of manure applied in the area to be tested, in kg; Z N is the nitrogen demand of manure in the tested area, in kg; X is the total nitrogen content in manure, in %;

[0095] Formula V;

[0096] In formula V, W is the annual fertilizer application amount in the tested area, in kg; Z N is the nitrogen demand of manure in the tested area, in kg; E1 is the proportion of the first manure in fertilizer application, in %; and D is the total nitrogen content in the fertilizer, in %.

[0097] The method provided by the present invention can optimize the amount and method of manure application according to the initial nutrient status of the soil, crop requirements and expected carbon fixation targets; while considering the soil nutrient requirements and carbon fixation effect, the amount of fertilizer applied can be minimized while maximizing the soil carbon fixation rate. The method provided by the present invention can promote the sustainability of agricultural production, improve resource utilization efficiency, and reduce greenhouse gas emissions.

[0098] In order to further illustrate the present invention, a method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0099] Example 1

[0100] The present invention selected farmland around a breeding farm in Longyan City, Fujian Province for experiment. After testing, the farmland was all paddy soil, and the crops planted were all rice. The farmland was divided into 15 plots with an area of ​​1 mu. After the crops were harvested and before sowing (preferably within 15 days after harvest), the five-point sampling method was used to sample 5 plots with an area of ​​1 m2 in each plot with uniform growth. 2 The initial organic carbon storage of the 0-30 cm tillage layer soil was measured by sampling squares. Fertilizers with different manure-to-fertilizer ratios (the total fertilizer application amount was the same) were applied to each sub-area. The following year, five 1 m2 squares with uniform growth in each plot were sampled using the five-point sampling method before sowing after the crop was harvested (preferably within 15 days after harvest). 2 The square blocks were sampled to determine the initial organic carbon storage and total nitrogen content of the 0-30cm tillage layer, and the yield after harvest was calculated. It can be seen that the total nitrogen content of the farmland soil is about 0.61g / kg, and the annual output is about 4217000kg / mu. Combining Table 1 and Table 2, it can be seen that the nitrogen nutrient requirement per unit output is 2.2kg, and the soil nitrogen fertilization supply accounts for about 55%; according to the recommended value, the seasonal utilization rate of nitrogen in manure is determined to be 25%. The soil carbon fixation rate of each sub-area is calculated by referring to the annual change of the organic carbon pool in farmland soil in the standard "Technical Specifications for Carbon Sequestration Accounting in Farmland Soils", and formula III is used to calculate the manure nitrogen demand of different sub-areas at different manure fertilizer ratios;

[0101] Formula III;

[0102] In Formula III, Z N is the nitrogen requirement of manure in the area to be tested, in kg;

[0103] N a The annual crop yield or total area of ​​the area to be tested, in kg or hm 2 ; Artificial forest land is calculated by total area, and other crops are calculated by annual output;

[0104] N b Form 100 kg or 1m for the crops in the area to be tested 3 The nitrogen requirement for production is in kg; for artificial forest land, in 1m 3 The yield of other crops is calculated based on 100 kg yield;

[0105] XN It is the proportion of fertilizer supply determined according to the total nitrogen content of the area to be tested, in %;

[0106] E1 is the proportion of the first manure in fertilizer application, unit is %;

[0107] W N is the utilization rate of manure nitrogen in the season, in %. The results are shown in Table 3.

[0108] Table 3 Experimental parameters

[0109]

[0110] The spsspro software (https: / / www.spsspro.com / ) was used to perform polynomial regression analysis on the soil carbon fixation rate and manure-to-fertilizer ratio in Table 3, and the comprehensive response relationship between different manure-to-fertilizer ratios and soil carbon fixation rate was fitted. 2 is the multiple determination coefficient, R 2 The values ​​are all close to 1, and the fitting effect is good. RMSE is the root mean square error. The closer the value is to 0, the smaller the error and the better the prediction. The evaluation results of the fitting times of 3 are shown in Table 4. It can be seen from the fitting results that the fitting effect of different manure ratios and soil carbon fixation rate is good.

[0111] Table 4 Fitting evaluation table

[0112]

[0113] When the number of times is 3, the standardized formula of the model fitted by the data is:

[0114] V=1615.676-49318.623E+491701.357E 2 -1462419.967E 3 Formula V;

[0115] Where: V is the soil carbon fixation rate, unit is kg / hm 2 a; E is the proportion of manure to fertilizer applied, in %.

[0116] According to the above formula, the soil carbon fixation rate is the highest when the manure accounts for about 14.84% of the fertilizer application ratio in this area, and the manure nitrogen demand in this area is 3019.9t, and the soil carbon fixation rate is about 345.91kg / hm 2 a. In this embodiment, the total nitrogen content in the manure accounts for about 2%. It is calculated that the annual application amount of manure is 150995.9 tons, the total nitrogen content in the fertilizer accounts for about 45%, and the annual application amount of the fertilizer is 38510.7 tons.

[0117] Comparative Example 1

[0118] The spsspro software (https: / / www.spsspro.com / ) was used to perform polynomial regression analysis on the soil carbon fixation rate and the ratio of manure to fertilizer in Table 3. The evaluation results with fitting times of 1, 2 and 4 are shown in Table 5.

[0119] Table 5 Evaluation table of different fitting times

[0120]

[0121] It can be seen from Tables 4 and 5 that the polynomial fitting effect when the fitting number is 3 is better than that when the fitting number is 1 and 2, and the fitting number is 4 and the fitting number is not much different from 3. However, it is not convenient to calculate the soil nutrient demand when the soil carbon fixation rate is the maximum, so the polynomial equation with a fitting number of 3 is selected.

[0122] Comparative Example 2

[0123] The spsspro software (https: / / www.spsspro.com / ) was used to perform power approximation fitting on the soil carbon fixation rate and the ratio of manure to fertilizer in Table 3. The formulas selected types 1 and 2 respectively. The fitting evaluation results are shown in Table 6.

[0124] Table 6 Evaluation table of different fitting times

[0125]

[0126] It can be seen from Tables 4 and 5 that the polynomial fitting effect is better than the power approximation fitting when the fitting number is 3.

[0127] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for regulating fertilization based on soil carbon fixation rate and land manure nutrient demand, characterized in that: The following steps are involved: 1) Divide the area to be regulated into different test areas according to soil type and crop type, and each test area has only one soil type and one crop; each test area is processed in steps 2) to 7); 2) Divide the area to be tested into 10 to 20 sub-areas, return manure to the fields at different proportions in each sub-area, and obtain sub-areas with different proportions of manure to fertilizer application; 3) The soil carbon fixation rate after returning manure to the fields in different sub-regions was determined, and the soil carbon fixation rate and the proportion of manure to fertilizer in different sub-regions were subjected to polynomial approximation regression analysis to fit the response relationship between the soil carbon fixation rate and the proportion of manure to fertilizer, as shown in Formula I: Formula I; In formula I, V is the soil carbon fixation rate, in kg / hm 2 a; E is the proportion of manure to fertilizer, unit is %; a1, a2 and c are constants, n is an integer, and n≥1; The proportion of manure to fertilizer is calculated according to formula II: E=A / B×100% Formula II; In formula II, E is the proportion of manure to fertilizer, in units of %; A is the total nitrogen content in manure applied to the soil, in units of kg; B is the total nitrogen content in fertilizer applied to the soil, in units of kg; the fertilizer includes manure and chemical fertilizer; 4) Calculate the multiple determination coefficient and root mean square error for different values ​​of n in formula I, select formula I corresponding to the value of n when the multiple determination coefficient is close to 1 and the root mean square error is close to 0, and obtain the fitting formula for soil carbon fixation rate and the proportion of manure in fertilizer application; 5) Using the fitting formula, the proportion of manure to fertilizer applied when the soil carbon fixation rate is the maximum is calculated to obtain a first proportion of manure to fertilizer applied; 6) calculating the nitrogen demand of manure in the tested area using the first manure-fertilizer ratio; The nitrogen demand of manure in the tested area is calculated using Formula III: Formula III; In Formula III, Z N is the nitrogen requirement of manure in the area to be tested, in kg; N a The annual crop yield or total area of ​​the area to be tested, in kg or hm 2 ; Artificial forest land is calculated by total area, and other crops are calculated by annual output; N b Form 100 kg or 1m for the crops in the area to be tested 3 The nitrogen requirement for production is in kg; for artificial forest land, in 1m 3 The yield of other crops is calculated based on 100 kg yield; X N It is the proportion of fertilizer supply determined according to the total nitrogen content of the area to be tested, in %; E1 is the proportion of the first manure in fertilizer application, unit is %; W N is the utilization rate of nitrogen in manure in the current season, unit is %; 7) Determine the annual fertilizer application amount of the tested area using the nitrogen demand of the manure, the total nitrogen content in the manure, and the proportion of the first manure in fertilizer application; the annual fertilizer application amount of the tested area includes the annual application amount of manure and the annual application amount of chemical fertilizer, and the annual application amount of manure and the annual application amount of chemical fertilizer in the tested area are determined using Formula IV and Formula V respectively: Y = Z N Type IV / X; In formula IV, Y is the annual amount of manure applied in the area to be tested, in kg; Z N is the nitrogen demand of manure in the tested area, in kg; X is the total nitrogen content in manure, in %; Formula V; In formula V, W is the annual fertilizer application amount in the tested area, in kg; Z N is the nitrogen demand of manure in the tested area, in kg; E1 is the proportion of the first manure in fertilizer application, in %; and D is the total nitrogen content in the fertilizer, in %.

2. The method according to claim 1, characterized in that The soil carbon fixation rate is the soil carbon fixation rate one year after manure is returned to the field.

3. The method according to claim 1, characterized in that When the crop planted in the tested area is rice, n in Formula I=3.

4. The method according to claim 1, characterized in that: Different crops form 100 kg or 1m 3 The nitrogen requirements for production are as follows: Artificial forest land is 1m 3 The yield of other crops is calculated based on 100 kg.

5. The method according to claim 1, characterized in that The fertilizer supply ratio determined based on the total nitrogen content of the area to be tested includes: The crops grown in the dry land are field crops; The total nitrogen content of the area to be tested is the total nitrogen content measured in farmland where manure has been continuously returned to the fields for 3 years or more.

6. The method according to claim 1 or 5, characterized in that: The method for determining the total nitrogen content of the area to be measured includes: adopting a 5-point sampling method, determining the total nitrogen content of 5 sampling points, and taking the average value of the total nitrogen content of the 5 sampling points.

7. The method according to claim 6, characterized in that Soil from three tillage layers (0~10cm, 10~20cm and 20~30cm) was taken from each sampling point, and the total nitrogen content was determined after the soil from the three tillage layers was mixed.

8. The method according to claim 1, characterized in that The nitrogen utilization rate of the manure in this season is 25% to 30%.

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