Method for reducing plant pesticide through combination of percarbamide and nitrification inhibitor and application of method

Abstract

The invention relates to the technical field of soil treatment, in particular to a method for reducing plant pesticide through combination of percarbamide and a nitrification inhibitor and application of the method. Different nitrification inhibitors are taken as nitrogen management measures to influence soil non-biological characteristics and bacterial communities to drive degradation of carbendazim. Vegetables (carrots) are used as test crops, nitrification inhibitors including dicyandiamide (DCD), 3, 4-dimethyl pyrazole phosphate (DMPP) and nitrogenous fertilizer (percarbamide) are applied to different test soil (dry farming and rice soil), carbendazim is sprayed in the growth period (the application amount is 5 mg kg <-1 >, 7 days per time), and the nitrogen fertilizer (percarbamide) is applied to the test soil (dry farming and rice soil). Results show that by applying the nitrification inhibitors (DCD and DMPP) and percarbamide, not only can the yield of carrots and the diversity and network stability of bacterial communities be increased, but also carbendazim residues in soil and carrots can be reduced.

Description

Technical Field

[0001] This invention relates to the field of soil treatment technology, specifically to a method and its application of combining percarbamide and nitrification inhibitors to reduce pesticide use in plants. Background Technology

[0002] Carbendazim is a benzimidazole fungicide and a systemic fungicide, widely used in intensive agriculture to control fungal diseases. However, carbendazim degrades slowly and has low water solubility, with its primary source in crops being the soil. Improper use of carbendazim can lead to high residue levels in soil and crops, posing a toxic risk to mammals. Reports indicate that carbendazim is chemically stable, with a half-life in the soil typically ranging from 6 to 12 months. The recommended application frequency for carbendazim in greenhouse agriculture is once every 7-10 days, but excessively high dosages and frequent applications significantly increase its half-life in the soil, leading to residue accumulation and threatening the ecological safety of soil and water bodies. Residual carbendazim in the soil environment can be absorbed by crops and, through the food chain, accumulate, thus threatening human health. Currently, excessive carbendazim residues are found in environmental samples, vegetables, and fruits in my country. Carbendazim residues may lead to the deterioration of agricultural ecosystems and soil quality degradation. Carbendazim intake can also seriously threaten human health, including endocrine disorders and cancer.

[0003] Besides pesticide application, large amounts of nitrogen fertilizer are also required in facility agriculture management. Nitrogen is an essential nutrient for crop growth and metabolism, and nitrogen addition can also promote soil microbial activity and alter the metabolic processes of the soil microbial community. Although fertilization can increase soil nitrogen supply, soil nitrification converts ammonium nitrogen into nitrate nitrogen, leading to nitrogen loss through nitrous oxide emissions and providing a substrate for denitrification. Therefore, excessive application of chemical fertilizers can result in low fertilizer utilization efficiency and exceed the basic requirements for crop growth. Nitrification inhibitors are substances that can regulate the abundance of nitrogen cycle genes, reduce nitrification and ammonia volatilization. They are also an effective and feasible management measure that can reduce nitrate accumulation in crops and promote nitrogen fertilizer utilization efficiency. Commonly used commercial nitrification inhibitors include DCD and DMPP. The addition range of nitrification inhibitors supported by production standards is generally 1% to 2% of the nitrogen content in the fertilizer. Percarbonamide, also known as peroxide urea, is a safe and non-toxic nitrogen fertilizer that is easily soluble in water and combines the properties of hydrogen peroxide and urea. When applied to the soil environment, urea peroxide hydrolyzes and gradually releases free radicals, oxygen atoms, and oxygen. Urea peroxide can provide oxygen for the root respiration of plants, thereby improving the aeration of agricultural soils. It is a relatively ideal rhizosphere oxygen-providing chemical fertilizer.

[0004] Besides biostimulation, electron transfer during the nitrogen cycle can also couple with the degradation of organic pollutants. Therefore, to address pesticide pollution in greenhouse agricultural soils, a combined approach of biostimulation, nitrogen cycle regulation, and chemical oxidation can promote the remediation of pesticide-contaminated soils from multiple angles, comprehensively, and holistically. Nitrification inhibitors can regulate the coupling effect of electron transfer in the nitrogen cycle and the degradation of organic pollutants by inhibiting soil nitrification and reducing the content of nitrate nitrogen, a substrate for denitrification, thus further influencing fungicide degradation and plant uptake. Currently, most studies focus only on the impact of nitrification inhibitors on crop yield, with fewer studies considering pollutant degradation, nitrogen cycle, plant endophytes, crop quality, and pollutant residues. Therefore, research is needed to explore the effects of superoxide dismutase (SOD) alone or in combination with nitrification inhibitors on fungicide residues in soil and crops. Simultaneously, a systematic analysis of crop yield and fungicide residue data in soil and crops is necessary to ensure both crop yield and reduced fungicide residues, thus creating a virtuous cycle in greenhouse agricultural production. Summary of the Invention

[0005] In order to promote plant growth and reduce the residue of the pesticide carbendazim in soil and plants, the present invention provides the following technical solution.

[0006] A method for reducing phytochemical pesticide use by combining percarbonamide and a nitrification inhibitor, the method comprising treating soil with a composition containing percarbonamide and a nitrification inhibitor; wherein the nitrification inhibitor comprises one or more of dicyandiamide and 3,4-dimethylpyrazole phosphate; and wherein the phytochemical pesticide is carbendazim.

[0007] A composition that promotes plant growth and reduces the residues of the pesticide carbendazim in soil and plants, the composition comprising percarbamide and a nitrification inhibitor; the nitrification inhibitor comprising one or more of dicyandiamide and 3,4-dimethylpyrazole phosphate.

[0008] Preferably, the nitration inhibitor is dicyandiamide.

[0009] Preferably, the concentration ratio of the percarbonamide to the dicyandiamide is 100:1.

[0010] Preferably, the nitration inhibitor is 3,4-dimethylpyrazole phosphate.

[0011] Preferably, the concentration ratio of the percarbonamide to the 3,4-dimethylpyrazole phosphate is 100:1.

[0012] Preferably, the nitration inhibitor is dicyandiamide and 3,4-dimethylpyrazole phosphate.

[0013] Preferably, the concentration ratio of the nitration inhibitor dicyandiamide to the 3,4-dimethylpyrazole phosphate is 1:1.

[0014] Preferably, the concentration ratio of the percarbonamide to the nitration inhibitor is 100:1.

[0015] The application of a composition that promotes plant growth and reduces pesticide residues in soil and plants in promoting plant growth and influencing pesticide residues in soil and plants.

[0016] A planting method for promoting plant growth and reducing the residue of the pesticide carbendazim in soil and plants, comprising planting plants in soil treated with a composition comprising percarbamide and a nitrification inhibitor; wherein the nitrification inhibitor comprises one or more of dicyandiamide and 3,4-dimethylpyrazole phosphate.

[0017] The present invention has the following beneficial effects:

[0018] (1) Taking the remediation of pesticide (carbendazim) pollution in agricultural soils as a starting point, this study investigates how to promote pesticide degradation in agricultural soils from multiple angles, in a comprehensive and three-dimensional manner through the combined use of biostimulation, nitrogen cycle regulation, and chemical oxidation. Nitrification inhibitors (DMPP and DCD) can regulate soil nitrogen transformation processes, thereby promoting crop growth and affecting pesticide residues in soil and plants. This invention combines soil stoichiometry, microbiology, and molecular biology techniques to study the mechanisms regulating the degradation and translocation of carbendazim in soil and plants, reflecting the interdisciplinary nature of environmental science, microbiology, and plant nutrition, and demonstrating both technological advancement and interdisciplinary nature.

[0019] (2) There are few studies on the process and mechanism by which different nitrification inhibitors and percarbamide promote pesticide degradation. In the remediation of organic pollution in agricultural soils, microbial communities and biostimulation are the core targets of in-situ bioremediation strategies, and the processes of nitrification and denitrification are also coupled with the degradation of organic pollutants. By combining technologies from different disciplines, we can explore the process and mechanism by which biostimulation and nitrogen cycling promote the degradation of carbendazim at a higher and more complex overall level, so as to provide technical support for ensuring the yield and quality of agricultural products, mitigating the environmental health risks of pesticides, and improving nutrient utilization.

[0020] (3) The present invention found that the application of different nitrification inhibitors and percarbonamide can not only increase carrot yield, but also reduce carbendazim residues in the soil-crop system. Therefore, nitrification inhibitors have broad application prospects in agricultural systems. Attached Figure Description

[0021] Figure 1 The technical solution route of the present invention.

[0022] Figure 2 Effects of percarbamide and nitrification inhibitor application on (a) soil versatility, (b) carbendazim residues in soil and (c) carrot yield by fresh weight and (e) dry weight in different soils. Lowercase letters indicate significant differences between five different treatments within the same soil type, and uppercase letters indicate significant differences between different soil types within the same treatment. CK, blank control; UA, percarbamide application; UDCA, percarbamide + DCD application; UDMA, percarbamide + DMPP application; UDDA, percarbamide + 1 / 2 (DCD + DMPP) application.

[0023] Figure 3 The effects of applying percarbamide and nitrification inhibitors to different soil types on (a) ACE and (b) Chao1 richness estimates, (c) Shannon and (d) Invsimpson diversity indices, and (e) ACE and (f) Chao1 richness and (g) Shannon and (h) Invsimpson diversity indices of soil bacterial communities. Lowercase letters indicate significant differences among the five different treatments of the same soil type, and uppercase letters indicate significant differences among different soil types of the same treatment.

[0024] Figure 4 Effects of percarbamide and nitrification inhibitor application on the phylum-level distribution of (a) soil bacteria and (b) endophytic bacteria in different soils, and principal coordinate analysis of bacterial communities in (c) soil, (d) plant and (e) soil-plant systems.

[0025] Figure 5 (a) Co-occurrence networks of soil bacterial communities in dryland soil and (b) paddy soil, and (c) topological features of soil bacterial community co-occurrence networks, and (d) co-occurrence networks of endophytic bacterial communities in carrots grown in dryland soil and (e) paddy soil, and (f) topological features of endophytic bacterial community co-occurrence networks.

[0026] Figure 6Relationships between bacterial communities, soil physicochemical properties, enzyme activity, and carbendazim residues: (a) Dryland soil, with random forest interpreting the relative importance of each analytical parameter for (b) carrot yield in dryland soil and (c) carbendazim residues. Relationships between bacterial communities, soil physicochemical properties, enzyme activity, and (d) carbendazim residues in paddy soil, and the relative importance of random forest interpreting analytical parameters for (e) carrot yield and (f) carbendazim residues in paddy soil; (g) Relationships between endophytic bacterial communities, carrot yield, and carbendazim residues in dryland soil, and the relative importance of random forest interpreting analytical parameters for (h) carrot yield in dryland soil and (i) carbendazim residues in carrot; (j) Relationships between endophytic bacterial communities, carrot yield, and carbendazim residues in paddy soil, and the relative importance of random forest interpreting analytical parameters for (k) carrot yield and (l) carbendazim residues in paddy soil.

[0027] Figure 7 Path analysis revealed quantitative associations between soil multifunctionality, enzyme activity, bacterial community, and carbendazim residue levels with the standardized total effect: (a) carbendazim residue levels in dryland soils, (b) the standardized total effect of each factor on carbendazim residue levels in dryland soils, (c) carbendazim residue levels in paddy soils, (d) the standardized total effect of each factor on carbendazim residue levels in paddy soils, (e) carbendazim residue levels in carrots grown in dryland soils, (f) the standardized total effect of each factor on carbendazim residue levels in carrots grown in dryland soils, (g) carbendazim residue levels in radishes grown in paddy soils, and (f) the standardized total effect of each factor on carbendazim residue levels in carrots grown in paddy soils. The data above the arrows represent the standardized direct effects. Red and blue arrows indicate significant positive and negative relationships, respectively, while solid and dashed arrows indicate obvious positive or negative relationships, respectively. Significant differences are represented by *P < 0.05, **P < 0.01, and ***P < 0.001. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] The technical solutions of the present invention are as follows:

[0030] 1. Test soil:

[0031] Two types of experimental soil (dryland soil and paddy soil) were taken from farmland at the Changsha Agricultural Environment Observation Station of the Chinese Academy of Sciences (E113°20'16",N28°33'25"). We collected the topsoil from the 0-20 cm depth, air-dried it, mixed it thoroughly, ground it, and sieved it (<2 mm).

[0032] 2. Chemical reagents:

[0033] Dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China), chemically pure, with a purity >98.0%; carbendazim standard (purity >99.0%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. (Shanghai, China). Carbendazim reagent is a 50% active ingredient wettable powder produced by Jiangsu Lanfeng Biochemical Co., Ltd. Percarbonamide: Shanghai Maclean Biochemical Technology Co., Ltd. (Shanghai, China). Carrot seeds (Qingxuan Kuroda Gosun).

[0034] 3. Test instruments:

[0035] High-performance liquid chromatograph (HPLC) (Agilent Technologies, Germany), continuous flow analytical system (Sealanalytical, UK), high-speed and low-speed centrifuges, incubators, oil baths, drying ovens, etc.

[0036] 4. The specific technical solution of the present invention is as follows: Figure 1 The following is stated:

[0037] 4.1 Experimental Design:

[0038] The experimental design included five different experimental treatment groups: (1) Blank control: no nitrification inhibitors and percarbonamide (CK) were added; (2) Percarbonamide (UA: 200 mg N kg) was applied. -1 (3) Percarbonamide + DCD (UDCA) (200mg N kg) -1 and DCD: 2mg kg -1 (4) Percarbonamide + DMPP (UDMA) (200mg N kg) -1 And DMPP: 2mg kg -1 (5) Percarbonamide + 1 / 2 (DCD + DMPP) (UDDA) (200 mg N kg) -1 DCD and DMPP: 1 mg / kg each -1 Each experimental treatment group had 4 replicates.

[0039] Different treatments involved weighing experimental soil samples, and adjusting the soil moisture content to a suitable level for crop growth (60% of maximum water holding capacity). The seeds of the experimental crop (carrot) were surface-sterilized with a 10% (v / v) H₂O₂ solution, rinsed with distilled water, and dried with filter paper. They were then placed in a constant temperature incubator at 25°C in the dark until germination. After germination, the seeds were inoculated into the aforementioned flowerpots and placed in an artificial greenhouse for growth. Temperature and other data were observed and recorded daily, and water was added periodically. After 24 days of growth, the seedlings were thinned to 4 plants per plant. On day 27, percarbamide and nitrification inhibitors were dissolved in distilled water and evenly applied to the soil. On day 28, carbendazim was evenly applied to the plants and soil (5 mg / kg). -1 The fungicide was applied seven times (at 7-day intervals) at the manufacturer's recommended dosage. After 130 days, the plants and soil were collected. Once the crop matured, it was harvested, and the crop biomass and carbendazim residue levels in the edible portions were measured. Simultaneously, the experimental soil in the pots was mixed, and soil samples were collected for analysis of soil physicochemical properties, crop yield, quality, carbendazim residues, and microbiological characteristics.

[0040] 4.2 Basic physicochemical properties of soil, soil enzyme activity and microbial biomass

[0041] Soil pH, soil organic matter, total nitrogen, ammonium nitrogen and nitrate nitrogen, available phosphorus and available potassium, etc. Soil β-glucosidase, chitinase, urease, phosphatase and arylsulfatase activities.

[0042] 4.3 Determination of crop biomass, yield, and quality

[0043] After the experimental crops matured, the planted crops were harvested, washed, and drained. The fresh weight of the vegetables was measured and recorded as biomass. A portion was divided into portions and dried in an oven at 105℃ for 30 minutes to blanch the vegetables, followed by drying at 70℃ to constant weight. The moisture content was then calculated. Finally, the crop yield (yield based on both fresh and dry weight) was calculated. Additionally, the edible portions of the crops were weighed to determine their quality indicators: soluble sugar content was determined using the anthrone colorimetric method; soluble protein content was determined using the Coomassie brilliant blue method; and vitamin C content was determined using the 2,6-dichlorophenolindophenol colorimetric method.

[0044] 4.4 Determination of carbendazim content in soil and plant samples

[0045] Edible portions of the experimental crop were homogenized and, along with the experimental soil, freeze-dried. Acetonitrile was added for extraction, and the supernatant was rotary evaporated, diluted to volume with acetonitrile, and filtered through a 0.22 μm membrane. The concentration of carbendazim was then determined by HPLC-MS / MS. An external standard curve was plotted: the concentration of carbendazim was plotted on the x-axis, and the peak area on the y-axis. Separately, a portion of soil samples was freeze-dried for the determination of carbendazim content in the soil. The experimental crop and soil (freeze-dried) were extracted with distilled water and methanol, centrifuged, and the supernatant was rotary evaporated, diluted to volume with methanol (chromatographically), filtered through a 0.22 μm organic filter, and the concentration of carbendazim was determined by HPLC-MS / MS.

[0046] 4.5 Determination of soil microbial metagenomics and plant endophytic community

[0047] Soil microbial metagenomics and plant endophytic community assays were performed using methods described in relevant literature. Soil DNA was extracted and its concentration and quality were assessed. Qualified DNA samples were randomly fragmented into approximately 350 bp fragments using ultrasound. The entire library was prepared through end repair, sequencing adapter preparation, purification, and PCR amplification. After the library passed quality checks, high-throughput sequencing was performed.

[0048] After surface sterilization of plant samples, DNA was extracted and its concentration and quality were determined. Nested PCR was used to amplify the V5-V7 region of the 16 rRNA gene of endophytic bacteria: the first round of PCR used primers 779F and 1392R, producing a fragment of approximately 593 bp; the second round used primers 779F and 1193R, producing a fragment of approximately 394 bp. Primers ITS1F and ITS2R were used to amplify the ITS fragment, the internal transcribed spacer region of plant endophytic fungi. The PCR products were electrophoresed, gel-cleaved, and used to construct sequencing libraries for high-throughput sequencing. The sequencing data were filtered to obtain high-quality data.

[0049] 4.6 Data Analysis Methods

[0050] High-throughput sequencing data analysis: Soil metagenomic sequencing was followed by filtering to obtain clean data, which was then used for metagenome assembly, gene prediction, and redundancy removal to construct a gene catalogue. Starting from the gene catalogue, functional annotations were performed on metabolic pathways, homologous gene clusters, and carbohydrate enzymes; simultaneously, the abundance distribution of other functional genes was obtained. The SILVA and ITS databases were used as reference databases for bacteria and fungi, respectively, to reveal the relative abundance of plant endophytic bacteria and fungi at different taxonomic levels.

[0051] Statistical methods: Redundancy analysis or correlation analysis was used to reveal the comprehensive relationship between soil physicochemical properties, carbendazim degradation rate, microbial activity, and microbial community structure. Structural equation modeling was used to analyze the direct and indirect relationships between carbendazim degradation rate, nitrogen transformation rate, content of different nitrogen forms, and abundance of functional genes.

[0052] Results analysis:

[0053] 1. Figure 1 This is a roadmap of the technical solution of the present invention.

[0054] 2. Soil system pluripotency, carbendazim residue levels and yields in soil and carrot samples.

[0055] The soil system multifunctionality of dryland soils ranged from 0.57 to 0.76, and that of paddy soils ranged from 0.51 to 0.74. Under different soil conditions, the CK treatment showed the lowest soil system multifunctionality, while the UDDA treatment showed the highest. Compared with the control treatment, the UDDA treatment increased the system multifunctionality by 24.7% and 23.2% in dryland soils and paddy soils, respectively. Figure 2 a). Compared with the UA treatment in dryland soil, the soil carbendazim residues in the UDCA and UDDA treatments decreased by 25.8% and 63.9%, respectively. Compared with the UA treatment in paddy soil, the soil carbendazim residues in the UDCA, UDMA, and UDDA treatments decreased significantly by 70.2%, 74.6%, and 77.2%, respectively. Figure 2 (b) Compared with the UA treatment, the carbendazim residue in carrots was significantly reduced in the UDCA treatment. The carbendazim residue in carrots in the CK treatment in paddy soil was 48.49 ± 12.32 mg / kg. -1 Carrot carbendazim residues were significantly reduced in UDCA, UDMA, and UDDA treatments compared to UA treatment (38.59 ± 6.34 mg / kg). -1 Compared to the UDMA and UDDA treatments, the carbendazim residues in carrots decreased significantly, by 46.9% and 51.4%, respectively. Figure 2 c). In dryland soil, the carrot yield (fresh weight) of UDCA, UDMA, and UDDA was 2.45 times, 2.76 times, and 3.03 times that of the UA treatment, respectively. In paddy soil, the carrot yield (fresh weight) of the UDCA treatment was 131.7% of that of the UA treatment. Figure 2 d). In dryland soil, the carrot yield (dry weight) of the UDCA treatment was UA (214 kg hm²). -2 In paddy soil, the carrot yield (dry weight) of the UDCA treatment was 233.2% of that of the UA treatment (1091 kg hm²). -2 , Figure 2 e).

[0056] 3. Soil and endophytic bacterial community diversity

[0057] Compared with the CK treatment in dryland soil, the soil bacterial community diversity indices (ACE, Chao1, Shannon, and Invsimpson) were significantly reduced in the UA treatment. Figure 3 Compared with the UA treatment in dryland soil, the soil bacterial community α diversity (ACE, Chao1, Shannon, and Invsimpson) was increased in the UDCA, UDMA, and UDDA treatments (a-3d). Figure 3 a-3d). For carrots planted in dryland soil, the estimated richness values ​​of the endophytic bacterial community ACE and Chao1 were significantly lower in the UA treatment compared to the CK treatment. Figure 3 e and 3f), but there were no significant differences in the Shannon and Invsimpson diversity indices of endophytic bacteria between dryland soil and paddy soil. Figure 3 g and 3h).

[0058] 4. Soil and endophytic bacterial community structure

[0059] In dryland soils, compared with the CK treatment (0.30±0.02), the relative abundance of soil Proteobacteria in the UA treatment increased by 38.6%, but compared with the UA treatment, the relative abundance of Proteobacteria in the soils treated with UDCA, UDMA, and UDDA further decreased. Figure 4 a). Compared with the CK treatment (0.29±0.02) in paddy soil, the relative abundance of soil proteobacteria in the UA treatment decreased by 14.4%. Compared with the CK treatment, the relative abundance of actinobacteria in the UDCA, UDMA, and UDDA treatments significantly increased. The relative abundance of soil acidobacteria in the UA treatment significantly decreased. Figure 4 a). In paddy soil, the relative abundance of Chloroflexi in the UDCA treatment was 74.1% (0.06 ± 0.01) of that in the UA treatment. The UA treatment significantly reduced the relative abundance of soil Myxococcota, and compared with the UA treatment, the relative abundance of soil Myxococcota in the UDCA, UDMA, and UDDA treatments was further increased. Furthermore, the five treatments had no significant effect on the endophytic bacteria phylum, and soil type had no significant effect on the relative abundance of different endophytic bacteria. Figure 4 b).

[0060] UA treatment significantly altered the soil bacterial community structure. Compared with UA treatment, nitrification inhibitors also significantly altered the soil bacterial community structure. Figure 4 c). The structure of the endophytic bacterial community changed with the addition of percarbonamide; compared with UA treatment, the addition of nitrification inhibitors also altered the structure of the endophytic bacterial community. Figure 4 d). When all 80 samples were selected together, significant differences were found in the soil and endophytic bacterial community structure. Figure 4 e).

[0061] 5. Co-occurrence network of soil and endophytic bacteria communities

[0062] Topological diagrams of soil bacterial community structures in dryland and rice paddies are shown below. Figure 5 As shown in a and 5b. In the UA treatment, the edges and nodes of the bacterial community co-occurrence network in dryland soil were significantly reduced by 16.7% and 11.4%, respectively. Figure 5 c). However, compared with the UA treatment, the UDCA, UDMA, and UDDA treatments showed further improvements, and there were no significant differences among the CK, UDCA, UDMA, or UDDA treatments in dryland soils. Figure 5 c). Application of carbamate also significantly reduced the edges and nodes of the co-occurrence network of paddy soil bacteria communities, decreasing by 6.97% and 3.25%, respectively. However, compared to the UA treatment, the edges and nodes of the co-occurrence network in the UDCA, UDMA, and UDDA treatments were increased to the CK level. Figure 5 c). The network topology diagram of endophytic bacterial communities planted in dryland and paddy soils is shown below. Figure 5 As shown in d and 5e. In dryland soils, the application of percarbamide significantly reduced the number of nodes in the endophytic community co-occurrence network by 22.9%, but compared with the UA treatment (119±10), the number of nodes in the endophytic community co-occurrence network of the UDCA, UDMA, and UDDA treatments further increased by 24.6%, 17.9%, and 17.9%, respectively. Figure 5 f). For plants growing in paddy soil, the UDCA treatment significantly altered the nodes of the endophytic community co-occurrence network compared to the UA treatment; however, none of the five treatments had a significant effect on the edges and modularity of the endophytic community co-occurrence network. Figure 5 f).

[0063] 6. Factors affecting crop yield and carbendazim residues

[0064] In dryland soils, carbendazim content was negatively correlated with the relative abundance of actinomycetes (r = -0.10), while carrot yield was significantly positively correlated with Shannon (r = 0.52), Invsimpson (r = 0.59) diversity indices, and the relative abundance of actinomycetes (0.36). Figure 6a). Random forest models show that the cluster of bacterial community co-occurrence networks in dryland soils is a major predictor of carrot yield. Figure 6 b). Soil urease activity is a major predictor of carbendazim residues in both dryland and paddy soils. Figure 6 c and 6f). The content of carbendazim in carrots was negatively correlated with the relative abundance of *Actinomyces oryzae* (r = -0.13) and *Acidobacterium* (r = -0.10) in rice soil, as well as bacterial community diversity. Figure 6 d). Random forest models show that Chloroflexi is a major predictor of carrot yield in dryland soils. Figure 6 e). The content of carbendazim in carrots grown in dryland soils was negatively correlated with the relative abundance of endophytic actinomycetes. Figure 6 g). The random forest model showed that the endophytic bacterial community was the main predictor of carrot yield in dryland soils (6h). Soil carbendazim residue was the main predictor of carbendazim residue in carrots, at 6.75% in dryland soils and 12.99% in paddy soils. Figure 6 i and 6l). The content of carbendazim in carrots grown in paddy soil was negatively correlated with the relative abundance of endophytic actinomycetes (i and 6l). Figure 6 g). Random forest models show that the cluster of bacterial community co-occurrence networks in rice soil is a major predictor of carrot yield. Figure 6 k).

[0065] Path analysis results indicate that increased versatility in dryland soils reduces soil carbendazim residues. Figure 7 a). In dryland soils, the standardized total effect of carbendazim residues in carrots on soil carbendazim residues is positive ( Figure 7 b). Soil system multifunctionality, carbendazim residues in carrots, soil bacterial community co-occurrence network and structure, and soil enzyme activity were negatively correlated with carbendazim residues in paddy soils. Figure 7 c). The standardized total effect of the bacterial community structure of paddy soil on the soil carbendazim residue level is positive. Figure 7 d). Path analysis results showed that in dryland soils, carbendazim residues in carrots were positively correlated with soil multifunctionality, but negatively correlated with yield and endophytic bacterial community structure. Figure 7 e). The standardized total effect of carrot yield and endophytic bacterial community structure on the carbendazim residue level in carrots is negative. Figure 7 f). The multifunctionality and endophytic bacterial community structure of paddy soil were negatively correlated with the residue levels of carbendazim on carrots. Figure 7 g), but soil carbendazim residues have a positive standardized total effect on carbendazim residues in carrots (g), Figure 7 h).

[0066] The present invention has the following beneficial technical effects:

[0067] (1) Taking the remediation of pesticide (carbendazim) pollution in agricultural soils as a starting point, this study investigates how to promote pesticide degradation in agricultural soils from multiple angles, in a comprehensive and three-dimensional manner through the combined use of biostimulation, nitrogen cycle regulation, and chemical oxidation. Nitrification inhibitors (DMPP and DCD) can regulate soil nitrogen transformation processes, thereby promoting crop growth and affecting pesticide residues in soil and plants. This invention combines soil stoichiometry, microbiology, and molecular biology techniques to study the mechanisms regulating the degradation and translocation of carbendazim in soil and plants, reflecting the interdisciplinary nature of environmental science, microbiology, and plant nutrition, and demonstrating both technological advancement and interdisciplinary nature.

[0068] (2) There are few studies on the process and mechanism by which different nitrification inhibitors and percarbamide promote pesticide degradation. In the remediation of organic pollution in agricultural soils, microbial communities and biostimulation are the core targets of in-situ bioremediation strategies, and the processes of nitrification and denitrification are also coupled with the degradation of organic pollutants. By combining technologies from different disciplines, we can explore the process and mechanism by which biostimulation and nitrogen cycling promote the degradation of carbendazim at a higher and more complex overall level, so as to provide technical support for ensuring the yield and quality of agricultural products, mitigating the environmental health risks of pesticides, and improving nutrient utilization.

[0069] (3) The present invention found that the application of different nitrification inhibitors and percarbonamide can not only increase carrot yield, but also reduce carbendazim residues in the soil-crop system. Therefore, nitrification inhibitors have broad application prospects in agricultural systems.

Claims

1. A method for reducing plant pesticides by combining percarbonate and a nitrification inhibitor, characterized in that: The method comprises treating soil with a composition containing percarbamide and a nitrification inhibitor; the nitrification inhibitor comprises at least one of dicyandiamide and 3,4-dimethylpyrazole phosphate; and the plant pesticide is carbendazim.

2. A composition for promoting plant growth and reducing the residual amount of the pesticide carbendazim in soil and plants, characterized in that: The composition comprises percarbonate and a nitrification inhibitor; the nitrification inhibitor comprises at least one of dicyandiamide and 3,4-dimethylpyrazole phosphate.

3. The composition according to claim 2, characterized in that The nitrification inhibitor is dicyandiamide.

4. The composition according to claim 3, characterized in that The application ratio of the percarbonate amide to the dicyandiamide is 100:

1.

5. The composition according to claim 2, characterized in that The nitrification inhibitor is 3,4-dimethylpyrazole phosphate.

6. The composition according to claim 5, characterized in that The application ratio of the percarbamide and the 3,4-dimethylpyrazole phosphate is 100:

1.

7. The composition according to claim 2, characterized in that The nitrification inhibitors are dicyandiamide and 3,4-dimethylpyrazole phosphate.

8. The composition according to claim 7, characterized in that The application ratio of the nitrification inhibitor dicyandiamide and the 3,4-dimethylpyrazole phosphate is 1:

1.

9. The composition according to claim 8, characterized in that The application ratio of the percarbamide and the nitrification inhibitor is 100:

1.

10. Use of the method according to claim 1 or the composition according to any one of claims 2 to 9 for promoting plant growth and affecting the pesticide residues in soil and plants.

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