A method for predicting the half-life of pesticide degradation in soil with agricultural organic waste returned to field

Abstract

The application belongs to the field of pesticide environmental protection, and discloses a method for predicting pesticide degradation half-life in farmland organic waste returned soil. The method considers factors such as soil type, soil temperature, pesticide physicochemical properties, biomass carbon content and the like, and through indoor experiment simulation, a prediction model of pesticide degradation half-life in farmland organic waste returned soil is established by using a multiple linear regression method, so that the influence of farmland organic waste returned on the pesticide degradation half-life in soil can be evaluated, and the environmental risk of pesticide residue in farmland organic waste returned soil can be controlled more accurately.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of pesticide environmental protection, and particularly relates to a method for predicting the pesticide degradation half-life in soil to which agricultural organic waste is returned. BACKGROUND

[0002] Returning agricultural organic waste to the field has become the main way of its resource utilization, including crop straw, livestock and poultry manure, biogas residue, mushroom substrate, etc. These biomasses generally contain 15%-60% organic carbon components, which can supplement soil organic nutrients, improve soil microbial activity, accelerate soil nutrient turnover, promote the absorption and transformation of soil nutrients by crops, and increase crop yield after being input into the soil. However, it cannot be ignored that fresh livestock and poultry manure, straw and other biomasses carry part of pathogenic bacteria or insect eggs, which can easily lead to the outbreak of crop diseases and insect pests, thereby increasing the use of pesticides and bringing potential risks of pesticide pollution. At the same time, as an organic component, pesticide waste can adsorb the residual pesticides in the soil, affecting the biodegradation process of the pesticides, and further affecting the half-life and residual rate of the pesticides in the soil. Patent ZL201810838473.7 discloses a method for predicting the degradation rate of chloroamide pesticides in soil to which biogas residue is returned. The nutrients released by the biogas residue returned to the field can activate the metabolism and secretion of soil microbial enzymes, and to some extent, promote the degradation of chloroamide pesticides. However, due to the diversity of soil types, the complexity of microbial structure, and the difference in chemical structure of pesticides, the adsorption capacity of agricultural organic waste to pesticides shows chemical diversity. These factors together lead to the difference in the degradation of pesticides in the soil.

[0003] The half-life of pesticide degradation determines the speed of pesticide degradation in the soil, and its value has important reference value for evaluating the environmental pollution risk of pesticides. Therefore, in order to accurately evaluate the environmental impact of the addition of agricultural organic waste on pesticide residues in the soil, the present application considers factors such as soil type, soil temperature, physicochemical properties of pesticides, and carbon content of biomass, establishes a prediction model for the half-life of pesticide degradation in soil to which agricultural organic waste is returned through indoor experimental simulation and the method of multiple linear regression, which can be used to evaluate the influence of returning agricultural organic waste to the field on the half-life of pesticide degradation in the soil, and helps to more accurately control the environmental risk of pesticide residues in the soil to which agricultural organic waste is returned. SUMMARY

[0004] The present application is around the influencing factors of pesticide degradation process in the farmland soil of agricultural organic waste, considers multiple factors such as soil type, soil temperature, pesticide physicochemical properties, carbon content of agricultural organic waste, obtains the real value of pesticide degradation half-life under different conditions through experimental simulation, and through parameter screening and model optimization, a prediction method of pesticide degradation half-life in the farmland soil of agricultural organic waste is constructed. The method can be used for evaluating the influence of biomass such as livestock and poultry manure, biogas residue and straw returned to field on pesticide residue degradation half-life.

[0005] The technical scheme of the present application:

[0006] A prediction method of pesticide degradation half-life in the farmland soil of agricultural organic waste, the steps are as follows:

[0007] (1) Screening of pesticide degradation half-life influencing factors in the farmland soil of agricultural organic waste

[0008] Different sources of agricultural waste are collected, and the soil mixed with pesticides in advance is added according to the set proportion, stirred uniformly, and then placed in a dark room for culture, the culture temperature is set to 10-40 DEG C, and the culture time is 30-90 days; according to the predetermined time, the soil sample is collected, the residual pesticide in the soil sample is extracted, and the pesticide residue concentration in the soil is determined; the measured pesticide residue concentration is brought into the pesticide residue formula C t =C0e -kt , in the formula, C0 is the concentration of pesticide in the soil before degradation experiment (mg / kg), C t is the concentration of pesticide residue in the soil at t time during the degradation experiment (mg / kg), k is the degradation rate of pesticide in the soil, and t is the pesticide degradation time; after the experimental data is arranged, the degradation rate k of pesticide in the soil is obtained through fitting optimization, the degradation rate k of pesticide in the soil is brought into the compound half-life calculation formula T=ln2 / k, and the real value of pesticide degradation half-life in the soil is obtained; according to the standard method provided by soil chemical analysis, the main physicochemical properties of the soil are determined, including soil organic carbon content, soil total nitrogen content, soil pH, soil cation exchange capacity and soil silt clay ratio; the elemental analysis instrument is used to determine the soil organic carbon content, soil total nitrogen content and pH value of the agricultural waste; the physicochemical property basic information of the pesticide is obtained by referring to the pesticide manual and the original data website of compound properties, including pesticide molecular mass, molecular volume, water solubility, logK ow , H donor, H acceptor, free rotation bond and polar surface area; combined with the real value of pesticide degradation half-life in the soil, significant correlation analysis (significance P value is less than 0.05) is carried out, and the key influencing factors of pesticide degradation half-life are screened, including pesticide molecular mass, logK ow , H donor, H acceptor, free rotation bond, soil pH, soil organic carbon content of agricultural organic waste, soil organic carbon content and soil temperature.

[0009] (2) Construction of pesticide degradation half-life model in farmland organic waste returned to soil

[0010] Taking the pesticide degradation half-life as the dependent variable and the key influencing factors screened in step (1) as the independent variable, a multivariate linear regression method is used to set up a collinearity diagnosis, optimize the model parameters, and establish a prediction model for the pesticide degradation half-life in farmland organic waste returned to soil:

[0011] logT 1 / 2 = -4.146 + 0.013MW - 0.303HA + 0.685pH - 0.113FRB - 0.058TP - 0.168HD

[0012] - 0.137logK ow + 0.128SOC - 0.012BOC(R 2 = 0.817) Formula (1)

[0013] wherein, T 1 / 2 is the pesticide degradation half-life in soil, d; MW is the molecular weight of the pesticide; HA is the H acceptor of the pesticide molecule; HD is the H donor of the pesticide molecule; FRB is the free rotation bond of the pesticide molecule; logK ow is the octanol-water partition coefficient of the pesticide; SOC is the soil organic carbon content; pH is the soil pH value; BOC is the organic carbon content of the farmland waste, %; TP is the soil temperature, ℃; R 2 is the determination coefficient of the model.

[0014] The farmland organic waste includes livestock and poultry manure, biogas residue, mushroom substrate, straw, etc.

[0015] The soil types include black soil, sandy loam, brown soil, saline-alkali soil, etc.

[0016] The pesticide types include atrazine, fluazifop, acetochlor, metolachlor, etc. herbicides, metalaxyl, tricyclazole, tebuconazole, chlorothalonil, myclobutanil, etc. fungicides, diazinphos, imidacloprid, acetamiprid, etc. insecticides.

[0017] The farmland waste addition amount is 0-15% of the soil mass.

[0018] The initial concentration of the pesticide is set to 0-5 mg / kg.

[0019] The application considers the influence of factors such as soil type, soil temperature, pesticide physicochemical properties, and agricultural organic waste addition amount, obtains the real value of the pesticide degradation half-life under different conditions through indoor controllable experiment simulation, and through parameter screening and model optimization, a prediction method of the pesticide degradation half-life in the farmland organic waste added soil is constructed. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a comparison diagram of the model prediction value and the experimentally measured value. DETAILED DESCRIPTION

[0021] The specific embodiments of the application are further described below in combination with the drawings and technical solutions.

[0022] Example 1: Screening of soil physicochemical properties affecting pesticide degradation half-life in soil

[0023] Soil samples at different sampling points are collected, including 7 soil samples of black soil, black calcareous soil, sandy loam, meadow soil, brown soil and saline-alkali soil, 5% mushroom substrate is added to the soil, the initial concentration of atrazine in the soil is set to 2 mg / kg, after uniform stirring, the soil is placed in a dark room, the culture temperature is set to 25 DEG C, and the soil samples are collected at 0d, 1d, 5d, 10d, 15d, 20d, 30d and 50d, respectively, the experimental period is controlled within 50d, the pesticide residues in the soil samples are extracted, and the concentration of the pesticide residues in the soil is determined. The measured pesticide residue data is brought into the pesticide residue formula C t =C0e -kt After fitting optimization, the pesticide degradation rate k in the soil is obtained, the pesticide degradation half-life in the soil is obtained by the compound half-life calculation formula T=ln2 / k. According to the method of soil agrochemical analysis standard, the main physicochemical properties of the soil are determined, and the main physicochemical properties of the soil are shown in Table 1; the obtained soil physicochemical property information and the soil degradation half-life are subjected to correlation analysis, and the main soil environmental factors affecting the pesticide degradation half-life are the soil organic carbon content and the soil pH.

[0024] Table 1: Physicochemical property information of soil

[0025]

[0026]

[0027] Example 2: Screening of chemical and physical properties affecting pesticide degradation half-life in soil

[0028] The brown soil in Example 1 is used, 5% of the soil quality is added to the biogas residue, the initial concentration of the pesticide in the soil is set to 2 mg / kg, and the pesticide is divided into three groups of herbicides, insecticides and fungicides. The herbicides include atrazine, acetochlor, and isopropyl methylamine. The insecticides include imidacloprid and acetamiprid. The fungicides include triazole alcohol, azoxystrobin, and chlorothalonil. After stirring uniformly, it is placed in a dark room for culture, the culture temperature is set to 25℃, and the soil samples are collected at 0d, 1d, 5d, 10d, 15d, 20d, 30d and 50d respectively. The experimental period is controlled within 50d, the pesticide residues in the soil samples are extracted, and the concentration of the pesticide residues in the soil is determined. The measured pesticide residue data is brought into the pesticide residue formula C t =C0 e -kt After fitting optimization, the degradation rate k of the pesticide in the soil is obtained, and the degradation half-life of the pesticide in the soil is calculated by the compound half-life calculation formula T=ln2 / k. The main physicochemical properties of the compounds are summarized as shown in Table 2; the obtained pesticide physicochemical property information is correlated with the soil degradation half-life, and the main compound-related factors affecting the pesticide degradation half-life are the molecular weight, logK ow , H donor, H acceptor and free rotation bond of the compound.

[0029] Table 2 Main physicochemical properties of pesticides

[0030]

[0031]

[0032] Example 3 Screening of agricultural organic waste properties affecting the degradation half-life of pesticides in soil

[0033] Different sources of agricultural waste are collected, including fermented pig manure, sheep manure, chicken manure and unfermented pig manure, sheep manure, cow manure, mushroom substrate, biogas residue, corn straw and other 9 kinds of agricultural organic waste. The agricultural organic waste accounting for 5% of the soil quality is mixed with the soil, the initial concentration of triadimefon in the soil is set to 5 mg / kg, and after stirring uniformly, it is placed in a dark room for culture, the culture temperature is set to 25℃, and the soil samples are collected at 0d, 1d, 5d, 10d, 15d, 20d, 30d and 50d respectively. The experimental period is controlled within 50d, the pesticide residues in the soil samples are extracted, and the concentration of the pesticide residues in the soil is determined. The measured pesticide residue data is brought into the pesticide residue formula C t =C0 e -ktIn the formula, the degradation rate k of the pesticide in the soil is obtained after fitting and optimization, and the degradation half-life of the pesticide in the soil is calculated according to the compound half-life calculation formula T = ln2 / k. The organic carbon content, total nitrogen content and pH value of the agricultural organic waste are determined by the elemental analysis method, and the specific values are shown in Table 3. The obtained physical and chemical properties of the agricultural organic waste and the degradation half-life of the pesticide in the soil are subjected to correlation analysis, and the main factor affecting the degradation half-life of the pesticide in the soil is the organic carbon content of the agricultural waste.

[0034] Table 3 Main physical and chemical properties of agricultural organic waste

[0035]

[0036] Example 4 Construction of a prediction model for the degradation half-life of a pesticide in soil with different agricultural organic waste

[0037] Different sources of agricultural waste, including fermented pig manure, sheep manure, chicken manure and unfermented cow manure, mushroom substrate and straw, are collected. The agricultural waste is added to the soil at a mass ratio of 5%, and the initial concentration of the pesticide in the soil is set to 5 mg / kg. The pesticide includes imidacloprid and triadimefon. After stirring, the mixture is placed in a dark room at a temperature of 25°C. Soil samples are collected at 0 d, 1 d, 5 d, 10 d, 15 d, 20 d, 30 d and 50 d, and the experimental period is controlled within 50 d. The pesticide residues in the soil samples are extracted, and the concentration of the pesticide residues in the soil is determined. The measured pesticide residue data is brought into the pesticide residue formula C t = C0 e -kt In the formula, the degradation rate k of the pesticide in the soil is obtained after fitting and optimization, and the degradation half-life of the pesticide in the soil is calculated according to the compound half-life calculation formula T = ln2 / k. According to the main influencing factors screened in Examples 1, 2 and 3, the soil organic carbon content and soil pH are determined by referring to the standard method for soil agro-chemical analysis. The main physical and chemical properties of the pesticide, including molecular weight, logK ow , H donor, H acceptor, free rotation bond, and the organic carbon content of the agricultural organic waste are determined. A multivariate linear regression method is used to set up a collinearity diagnosis and optimize model parameters to establish a prediction model for the degradation half-life of the pesticide in soil with agricultural organic waste:

[0038] logT 1 / 2 = -3.004 + 0.019MW - 0.241HA + 0.607pH - 0.009FRB - 0.214logK ow + 0.513SOC

[0039] - 0.005BOC(R 2 = 0.713) Formula (2)

[0040] where T 1 / 2 is the half-life of the pesticide in soil, d; MW is the molecular mass of the pesticide; HA is the H-bond acceptors of the pesticide molecule; FRB is the free rotatable bonds of the pesticide molecule; logK ow is the octanol-water partition coefficient of the pesticide; SOC is the soil organic carbon content; pH is the soil pH; BOC is the organic carbon content of the biomass, %; R 2 is the determination coefficient of the model.

Claims

1. A method for predicting the half-life of a pesticide in soil to which an agricultural organic waste has been returned, characterized by, The steps are as follows: (1) Screening of factors affecting pesticide degradation half-life in soil with the addition of agricultural organic waste Collect agricultural waste from different sources, add to the soil mixed with pesticides in advance according to the set proportion, stir uniformly, put into dark room, set the culture temperature to 10-40 o C, culture for 30-90 days; according to the predetermined time, collect soil samples, extract the residual pesticides in the soil samples, and determine the concentration of pesticide residues in the soil; the measured pesticide residue concentration is brought into the pesticide residue formula C t = C0e -kt , in which C0 is the concentration of pesticides in the soil before degradation experiment, C t is the concentration of pesticide residues in the soil at t time during the degradation experiment, k is the degradation rate of pesticides in the soil, and t is the degradation time of pesticides; after the experimental data is sorted out and optimized by fitting, the degradation rate k of pesticides in the soil is obtained, and the real value of the degradation half-life of pesticides in the soil is obtained by bringing the degradation rate k of pesticides in the soil into the compound half-life calculation formula T = ln2 / k; according to the standard method provided by soil agrochemical analysis, the main physicochemical properties of soil are determined, including soil organic carbon content, soil total nitrogen content, soil pH, soil cation exchange capacity and soil silt clay ratio; the elemental analysis instrument is used to determine the soil organic carbon content, soil total nitrogen content and pH value of agricultural waste; refer to pesticide manual and compound property original data website to obtain the basic information of pesticide physicochemical properties, including pesticide molecular weight, molecular volume, water solubility, logK ow , H donor, H acceptor, free rotation bond and polar surface area; combined with the real value of the degradation half-life of pesticides in the soil, significant correlation analysis is carried out, and the significant P value is less than 0.05, the key influencing factors affecting the degradation half-life of pesticides are screened, including pesticide molecular weight, logK ow , H donor, H acceptor, free rotation bond, soil pH, soil organic carbon content of agricultural waste, soil organic carbon content and soil temperature; (2) Construction of pesticide degradation half-life model in soil with the addition of agricultural organic waste Taking the pesticide degradation half-life as the dependent variable and the key influencing factors screened in step (1) as the independent variable, a prediction model for the pesticide degradation half-life in soil with the addition of agricultural organic waste is established by using the multiple linear regression method, setting the collinearity diagnosis and optimizing the model parameters. logT 1 / 2 = -4.146 + 0.013MW - 0.303HA + 0.685pH - 0.113FRB - 0.058TP - 0.168HD -0.137 log K ow + 0.128 SOC - 0.012 BOC (R 2 = 0.817) Equation (1) where T 1 / 2 is the half-life of the pesticide in soil, d; MW is the molecular weight of the pesticide; HA is the H-acceptor of the pesticide molecule; HD is the H-donor of the pesticide molecule; FRB is the free rotating bond of the pesticide molecule; logK ow is the octanol-water partition coefficient of the pesticide; SOC is the soil organic carbon content; pH is the soil pH; BOC is the organic carbon content of the agricultural waste, %; TP is the soil temperature, o C; R 2 is the determination coefficient of the model.

2. The prediction method of claim 1, wherein, The agricultural organic waste is livestock and poultry manure, biogas residue, mushroom substrate or straw.

3. The prediction method of claim 1, wherein, The soil type is black soil, sandy loam, brown soil or saline-alkali soil.

4. The prediction method of claim 1, wherein, The pesticide type includes herbicides, fungicides and insecticides.

5. The prediction method of claim 1, wherein, The addition amount of the agricultural waste accounts for no more than 15% of the soil mass.

6. The prediction method of claim 1, wherein, The initial concentration of the pesticide is set to no more than 5 mg / kg.

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