Agricultural non-point source pollution loss approach identification method

Abstract

The invention provides an agricultural non-point source pollution loss approach identification method, and belongs to the technical field of non-point source pollution source comprehensive control. The method comprises the following steps: S1, constructing a simulation area and collecting parameters of the simulation area; s2, relevant parameters of the initial state of the farmland system are collected in the simulation area; s3, measuring intermediate data in the rainfall process of the farmland ecosystem in the simulation area; s4, the nitrogen and phosphorus release concentration Ce (t) of the water-soil interface under the rainfall splash erosion effect is calculated; s5, calculating according to the parameters in S1, S2, S3 and S4 to obtain a total nitrogen and phosphorus runoff loss flux and a nutrient runoff loss flux generated by the horizontal mixed plug flow path; s6, identifying a nutritive salt loss path; according to the method, the important factors influencing the paddy field nitrogen and phosphorus runoff loss can be accurately identified, the accuracy of evaluating the farmland non-point source pollution emission reduction effect is improved, and an important scientific basis is provided for optimization of an agricultural non-point source pollution emission reduction technology.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive control of non-point source pollution, and in particular relates to a method for identifying loss pathways of agricultural non-point source pollution. Background Art

[0002] Accurately estimate the amount of nutrient loss from farmland and identify key driving factors. The loss of nitrogen and phosphorus in the soil belongs to agricultural non-point source pollution, and therefore has important practical significance for reducing agricultural non-point source pollution and formulating strategies for preventing and controlling water eutrophication.

[0003] CN111551683A discloses a method for quantitatively measuring the release and transfer flux of nutrients in a wetland system under the action of splash erosion caused by precipitation. This invention takes the release and transfer flux of soil solutes under the action of raindrop splash erosion as a factor for the first time, increasing the accuracy of the amount of nutrient surface runoff loss. At present, the runoff loss process caused by splash erosion caused by precipitation can be decomposed into a release process and a mixed plug flow process, wherein the release process involves total release, net release, release adsorption and analysis process, and release and transfer as the splash erosion caused by precipitation occurs; the mixed plug flow process is accompanied by mixed plug flow transfer and mixed plug flow adsorption and analysis process. However, this invention overestimates the mixed plug flow adsorption and analysis flux of soil nitrogen and phosphorus, that is, the mixed plug flow adsorption and analysis flux of soil nitrogen and phosphorus is processed into a total adsorption and analysis flux (mixed plug flow adsorption and analysis flux and release adsorption and analysis flux), resulting in an underestimated net release flux, thereby underestimating its contribution to the loss of nutrient runoff in wetland systems caused by quantitative splash erosion caused by precipitation. CN116431954A discloses a method for quantifying the contribution of precipitation splash erosion to nutrient runoff loss in farmland ecosystems. This invention takes the soil solute adsorption and desorption flux under the action of raindrop splash erosion as a consideration for the first time, and refines the process into soil nitrogen and phosphorus mixed push flow adsorption and desorption flux and release adsorption and desorption flux. By correcting the net release flux of nutrients in farmland ecosystems due to precipitation splash erosion, the accuracy of nutrient surface runoff transport is increased.

[0004] In actual production trials, soil conditioners are usually used to reduce soil loss due to their ability to improve the soil. However, the same soil conditioner has significant differences in reducing nitrogen and phosphorus loss in different regions because soil conditioners prevent soil nutrient loss in different ways. The ways in which soil nutrient is lost in different regions during precipitation are also quite different. Therefore, it is of great significance to identify the pathways of nutrient loss in farmland ecosystems and then use different soil conditioners or formulate improvement strategies in a targeted manner. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for identifying the loss pathways of agricultural non-point source pollution. This method, for the first time, explores the nitrogen and phosphorus release and transfer fluxes in the horizontal and vertical directions of rice fields under the action of raindrop splash erosion, and can accurately identify the important factors affecting the loss of nitrogen and phosphorus runoff from rice fields, thereby improving the accuracy of evaluating the emission reduction effect of farmland non-point source pollution, and providing an important scientific basis for the optimization of agricultural non-point source pollution emission reduction technology.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for identifying the loss path of agricultural non-point source pollution, comprising the following steps:

[0008] S1. Construct a simulation area and collect simulation area parameters;

[0009] S2. Collect relevant parameters of the initial state of the farmland system in the simulation area;

[0010] S3. Intermediate data of precipitation process in the farmland ecosystem of the measurement simulation area;

[0011] S4. Calculate the nitrogen and phosphorus release concentration Ce(t) at the water-soil interface under the action of precipitation splash erosion;

[0012] S5 calculates the total nitrogen and phosphorus runoff loss flux and the nutrient runoff loss flux generated by the horizontal mixing flow pathway based on the parameters in S1, S2, S3, and S4;

[0013] S6. Identify nutrient loss pathways;

[0014] The identification method is:

[0015] The contribution rates of the nutrient runoff loss flux generated by the horizontal mixing push flow pathway and the nutrient runoff loss flux generated by nitrogen release at the water-soil interface to the total nitrogen and phosphorus runoff loss flux were calculated respectively, and the nutrient loss pathway was determined based on the contribution rates.

[0016] Preferably, the simulation area in S1 is a farmland ecosystem without gauze covering.

[0017] Preferably, the simulation area parameters in S1 include farmland area A and ridge height H0.

[0018] Preferably, the relevant parameters in S2 include the water level H(t) of the farmland ecosystem in the initial state and the initial nutrient concentration Cpaddy(t) of the paddy field water layer.

[0019] Preferably, the intermediate data in S3 includes the average nutrient concentration C in precipitation. pre (t); When runoff is generated, measure the continuous rainfall depth R after the runoff is generated (t+1) .

[0020] Preferably, the nitrogen and phosphorus release concentration Ce(t) at the water-soil interface in S4 is calculated according to the calculation formula of Ce(t) described in Chinese Patent No. 202310699523.9.

[0021] Preferably, the calculation formula for the total nitrogen and phosphorus runoff loss flux in S5 is:

[0022]

[0023] Where Qi is the total nitrogen and phosphorus runoff loss flux, A is the farmland area; C pre (t) is the average nutrient concentration in precipitation, R (t+1) is the continuous rainfall depth after runoff is generated, H (t) is the water level of the farmland ecosystem at time t, C paddy (t) is the initial nutrient concentration of the water layer in the paddy field at the beginning of rainfall, Ce(t) is the nitrogen and phosphorus release concentration at the water-soil interface under the splash erosion of rainfall, and H0 is the height of the ridge.

[0024] Preferably, the calculation formula for the nutrient runoff loss flux generated by the horizontal mixing plug flow pathway in S5 is:

[0025]

[0026] In the formula, Q Li is the nutrient runoff loss flux generated by the horizontal mixing and plugging pathway, A is the farmland area; C pre (t) is the average nutrient concentration in precipitation, R (t+1) is the continuous rainfall depth after runoff is generated, H (t) is the water level of the farmland ecosystem at time t, C paddy (t) is the initial nutrient concentration of the water layer in the paddy field at the beginning of rainfall, Ce(t) is the nitrogen and phosphorus release concentration at the water-soil interface under the splash erosion of rainfall, and H0 is the height of the ridge.

[0027] Preferably, the nutrient runoff loss flux generated by the release of nitrogen from the water-soil interface in S6 is in accordance with the E described in the Chinese patent No. 202310699523.9. N (t) is calculated using the calculation formula.

[0028] Preferably, the calculation methods of the contribution rate in S6 are:

[0029] The calculation formula for the contribution of nutrient runoff loss flux generated by nitrogen release at the water-soil interface to the total nitrogen and phosphorus runoff loss flux is:

[0030]

[0031] The calculation formula for the contribution rate of nutrient runoff loss flux generated by the horizontal mixing push flow pathway to the total nitrogen and phosphorus runoff loss flux is:

[0032]

[0033] Preferably, after the nutrient loss pathway is identified, the nutrient loss is targeted and controlled according to the loss pathway.

[0034] Contains at least the following beneficial technical effects:

[0035] The present invention found that the runoff loss mechanism mainly includes the mixing and pushing effect in the horizontal direction and the splashing and releasing effect in the vertical direction. By detecting and calculating the contribution rate of the two to the nutrient runoff loss of the agricultural ecosystem, the soil nutrient loss pathways in different regions can be accurately determined, and soil conditioners or improvement methods can be evaluated, thereby carrying out targeted soil improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The contribution rate of nitrogen runoff loss from different sources. DETAILED DESCRIPTION

[0037] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0038] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0039] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0040] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0041] The sources of nitrogen loss in rice field runoff mainly include rainfall, irrigation, nitrogen release at the water-soil interface and mixing flow.

[0042] Patent CN116431954A discloses a method for quantifying the contribution of precipitation splash erosion to nutrient runoff loss in farmland ecosystems. The method discloses the net release flux E of precipitation splash erosion to the nutrient runoff loss in farmland ecosystems. N The correction formula for (t) is: N (t) = Q N (t)-SE N (t). The release of nitrogen from the water-soil interface is based on the effect of precipitation splash erosion on rice fields. The contribution rate of nitrogen release from the water-soil interface is equal to the ratio of the net release flux of precipitation splash erosion to the runoff. It can be calculated according to the calculation formula for the contribution of precipitation splash erosion to the nutrient runoff loss of farmland ecosystems recorded in patent CN116431954A. The calculation formula is:

[0043]

[0044] Furthermore, the present invention found that the main influencing factors of nitrogen runoff loss in rice fields are nutrient runoff loss caused by horizontal mixing and push flow pathways and nitrogen release at the water-soil interface. By exploring the contribution rate of the two to nitrogen runoff loss in rice fields, the nutrient loss pathway of the plot can be determined and targeted control can be carried out.

[0045] Specifically, the method for identifying the loss pathway of agricultural non-point source pollution includes the following steps:

[0046] S1. Construct a simulation area and collect simulation area parameters;

[0047] S2. Collect relevant parameters of the initial state of the farmland system in the simulation area;

[0048] S3. Intermediate data of precipitation process in the farmland ecosystem of the measurement simulation area;

[0049] S4. Calculate the nitrogen and phosphorus release concentration Ce(t) at the water-soil interface under the action of precipitation splash erosion;

[0050] S5 calculates the total nitrogen and phosphorus runoff loss flux and the nutrient runoff loss flux generated by the horizontal mixing flow pathway based on the parameters in S1, S2, S3, and S4;

[0051] S6. Identify nutrient loss pathways;

[0052] The identification method is:

[0053] The contribution rates of the nutrient runoff loss flux generated by the horizontal mixing push flow pathway and the nutrient runoff loss flux generated by nitrogen release at the water-soil interface to the total nitrogen and phosphorus runoff loss flux were calculated respectively, and the nutrient loss pathway was determined based on the contribution rates.

[0054] The simulation area described in S1 is a farmland ecosystem without gauze covering.

[0055] The simulation area parameters in S1 include the farmland area A and the ridge height H0.

[0056] The relevant parameters in S2 include the water level height H(t) of the farmland ecosystem in the initial state and the initial nutrient concentration Cpaddy(t) of the paddy field water layer.

[0057] The intermediate data in S3 include the average nutrient concentration C in precipitation. pre (t); When runoff is generated, measure the continuous rainfall depth R after the runoff is generated (t+1) .

[0058] The nitrogen and phosphorus release concentration Ce(t) at the water-soil interface in S4 is calculated according to the calculation formula of Ce(t) described in the Chinese patent No. 202310699523.9; specifically:

[0059] C e (t) = k1C Paddy (t)

[0060] The calculation formula for the total nitrogen and phosphorus runoff loss flux in S5 is:

[0061]

[0062] Where Qi is the total nitrogen and phosphorus runoff loss flux, A is the farmland area; C pre (t) is the average nutrient concentration in precipitation, R (t+1) is the continuous rainfall depth after runoff is generated, H (t) is the water level of the farmland ecosystem at time t, C paddy (t) is the initial nutrient concentration of the water layer in the paddy field at the beginning of rainfall, Ce(t) is the nitrogen and phosphorus release concentration at the water-soil interface under the splash erosion of rainfall, and H0 is the height of the ridge.

[0063] Preferably, the calculation formula for the nutrient runoff loss flux generated by the horizontal mixing plug flow pathway in S5 is:

[0064]

[0065] In the formula, Q Li is the nutrient runoff loss flux generated by the horizontal mixing and plugging pathway, A is the farmland area; C pre(t) is the average nutrient concentration in precipitation, R (t+1) is the continuous rainfall depth after runoff is generated, H (t) is the water level of the farmland ecosystem at time t, C paddy (t) is the initial nutrient concentration of the water layer in the paddy field at the beginning of rainfall, Ce(t) is the nitrogen and phosphorus release concentration at the water-soil interface under the splash erosion of rainfall, and H0 is the height of the ridge.

[0066] The nutrient runoff loss flux generated by the release of nitrogen at the water-soil interface in S6 is as described in the Chinese patent No. 202310699523.9. N (t) is calculated using the calculation formula.

[0067] The calculation methods of the contribution rates in S6 are:

[0068] The calculation formula for the contribution of nutrient runoff loss flux generated by nitrogen release at the water-soil interface to the total nitrogen and phosphorus runoff loss flux is:

[0069]

[0070] The calculation formula for the contribution rate of nutrient runoff loss flux generated by the horizontal mixing push flow pathway to the total nitrogen and phosphorus runoff loss flux is:

[0071]

[0072] The denominators in the two calculation formulas are the same, but they are expressed differently.

[0073] After identifying the nutrient loss pathways, targeted nutrient loss control is performed based on the loss pathways.

[0074] Example

[0075] (1) An artificial precipitation control experiment was conducted, with CK group (no gauze covering, no PAM addition, normal fertilization), NE group (gauze covering, no PAM addition, normal fertilization), and P1 group (no gauze covering, 2 g / m 2 PAM, normal fertilization) and P2 (no gauze covering, 4 g / m 2 PAM, normal fertilization) 4 treatments, each with 2 parallel plots, a total of 8 plots, each with an area of ​​6m 2 (2m×3m)

[0076] (2) Before, during, and after the start of precipitation, the saturated surface soil (0-20 cm) of the paddy fields in the plots was collected and placed in fresh-keeping boxes to prevent disturbance. The same precipitation intensity (60 mm / h), precipitation time (1 h), and precipitation splash force were controlled by an artificial precipitation control system. Surface water, runoff water, precipitation, and nitrogen and phosphorus release liquid at the water-soil interface of the paddy fields in the two plots were collected at 20 min, 40 min, and 60 min after the start of precipitation, and stored in a refrigerator for testing.

[0077] (3) Perform data collection and calculation according to the method described above.

[0078] Experimental results:

[0079] In the CK group, the contribution rate of nitrogen release from the water-soil interface to runoff loss was 20.6% after 20 minutes of rainfall, and the contribution rate of mixed push flow to runoff loss was 68.7%. In the P1 group, the contribution rate of nitrogen release from the water-soil interface to runoff loss was 22.3%, and the contribution rate of mixed push flow to runoff loss was 66.5%. In the P2 group, the contribution rate of nitrogen release from the water-soil interface to runoff loss was 23.0%, and the contribution rate of mixed push flow to runoff loss was 65.5%. The contribution rate of nitrogen release from the water-soil interface to runoff loss in the P1 and P2 groups was higher than that in the CK group, but not significantly (p>0.05).

[0080] After 40 minutes of rainfall, the contribution rate of nitrogen release from the water-soil interface to runoff loss in the CK group was 16.6%, and the contribution rate of mixed plug flow to runoff loss was 73.8%; the contribution rate of nitrogen release from the water-soil interface to runoff loss in the P1 group was 15.2%, and the contribution rate of mixed plug flow to runoff loss was 75.9%; the contribution rate of nitrogen release from the water-soil interface to runoff loss in the P2 group was 15.5%, and the contribution rate of mixed plug flow to runoff loss was 75.4%. In contrast to the 20 minutes of rainfall, the contribution rate of nitrogen release from the water-soil interface to runoff loss in the P1 and P2 groups was lower than that in the CK group; the contribution rate of nitrogen release from the water-soil interface to runoff loss in different treatments was significantly decreased compared with the 20 minutes of rainfall (p<0.05).

[0081] At 60 minutes after rainfall, the contribution rate of nitrogen release from the water-soil interface to runoff loss in group CK was 14.0%, and the contribution rate of mixed plug flow to runoff loss was 77.6%; the contribution rate of nitrogen release from the water-soil interface to runoff loss in group P1 was 13.4%, and the contribution rate of mixed plug flow to runoff loss was 78.5%; the contribution rate of nitrogen release from the water-soil interface to runoff loss in group P2 was 14.6%, and the contribution rate of mixed plug flow to runoff loss was 77.0%. There was no significant difference in the contribution rate of nitrogen release from the water-soil interface to runoff loss among different treatments (p>0.05).

[0082] Contribution rate of nitrogen runoff loss from different sources, see Figure 1It can be seen that the main factors affecting the nitrogen runoff loss in paddy fields are the nutrient runoff loss caused by the horizontal mixing flow pathway and the nitrogen release at the water-soil interface.

[0083] In this experiment, by comparing the nitrogen runoff loss, nitrogen release and nitrogen release transfer of different treatments during rainfall, it was found that the application of PAM could significantly reduce the nitrogen runoff loss (p<0.05), and increase the nitrogen release and release transfer but not significantly (p>0.05). Therefore, the reduction in runoff loss by adding polyacrylamide (PAM) mainly comes from the mixing and plugging process.

[0084] This proves that the method of the present invention can determine the loss path of nutrients in a plot of land, as well as the improvement path of soil conditioners or improvement methods.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for identifying the loss pathway of agricultural non-point source pollution, characterized in that: The following steps are involved: S1. Construct a simulation area and collect simulation area parameters; S2. Collect relevant parameters of the initial state of the farmland system in the simulation area; S3. Intermediate data of precipitation process in the farmland ecosystem of the measurement simulation area; S4. Calculate the nitrogen and phosphorus release concentration Ce(t) at the water-soil interface under the action of precipitation splash erosion; S5 calculates the total nitrogen and phosphorus runoff loss flux and the nutrient runoff loss flux generated by the horizontal mixing flow pathway based on the parameters in S1, S2, S3, and S4; S6. Identify nutrient loss pathways; The identification method is: The contribution rates of the nutrient runoff loss flux generated by the horizontal mixing push flow pathway and the nutrient runoff loss flux generated by nitrogen release at the water-soil interface to the total nitrogen and phosphorus runoff loss flux were calculated respectively, and the nutrient loss pathway was determined based on the contribution rates.

2. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The simulation area described in S1 is a farmland ecosystem without gauze covering.

3. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The simulation area parameters in S1 include the farmland area A and the ridge height H0; The relevant parameters in S2 include the water level height H(t) of the farmland ecosystem in the initial state and the initial nutrient concentration Cpaddy(t) of the paddy field water layer.

4. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The intermediate data in S3 include the average nutrient concentration C in precipitation. pre (t); When runoff is generated, measure the continuous rainfall depth R after the runoff is generated (t+1) .

5. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The nitrogen and phosphorus release concentration Ce(t) at the water-soil interface in S4 is calculated according to the calculation formula of Ce(t) described in the Chinese patent No. 202310699523.

9.

6. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The calculation formula for the total nitrogen and phosphorus runoff loss flux in S5 is: Where Qi is the total nitrogen and phosphorus runoff loss flux, A is the farmland area; C pre (t) is the average nutrient concentration in precipitation, R (t+1) is the continuous rainfall depth after runoff is generated, H (t) is the water level of the farmland ecosystem at time t, C paddy (t) is the initial nutrient concentration of the water layer in the paddy field at the beginning of rainfall, Ce(t) is the nitrogen and phosphorus release concentration at the water-soil interface under the action of precipitation splash erosion, and H0 is the height of the ridge.

7. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The calculation formula for the nutrient runoff loss flux generated by the horizontal mixing plug flow pathway in S5 is: In the formula, Q Li is the nutrient runoff loss flux generated by the horizontal mixing and plugging pathway, A is the farmland area; C pre (t) is the average nutrient concentration in precipitation, R (t+1) is the continuous rainfall depth after runoff is generated, H (t) is the water level of the farmland ecosystem at time t, C paddy (t) is the initial nutrient concentration of the water layer in the paddy field at the beginning of rainfall, Ce(t) is the nitrogen and phosphorus release concentration at the water-soil interface under the action of precipitation splash erosion, and H0 is the height of the ridge.

8. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The nutrient runoff loss flux generated by the release of nitrogen at the water-soil interface in S6 is as described in the Chinese patent No. 202310699523.

9. N (t) is calculated using the calculation formula.

9. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: The calculation methods of the contribution rates in S6 are: The calculation formula for the contribution of nutrient runoff loss flux generated by nitrogen release at the water-soil interface to the total nitrogen and phosphorus runoff loss flux is: The calculation formula for the contribution rate of nutrient runoff loss flux generated by the horizontal mixing push flow pathway to the total nitrogen and phosphorus runoff loss flux is:

10. The method for identifying the loss pathway of agricultural non-point source pollution according to claim 1, characterized in that: After identifying the nutrient loss pathways, targeted nutrient loss control is performed based on the loss pathways.

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