Method for reducing vegetable field soil non-point source pollution and nitrous oxide emission simultaneously

Abstract

The present application relates to the field of agricultural environmental protection method, particularly to a method for reducing the pollution of vegetable field soil non-point source and N2O.The method provided by the present application fully considers the carbon and nitrogen content, C / N and cellulose content of different exogenous carbon materials, reduces the application of chemical fertilizer nitrogen under the premise of ensuring the nitrogen supply of vegetables according to the nitrate nitrogen content of vegetable field soil, increases the amount of effective state carbon and the content of holocellulose by optimizing the combination and proportion of different exogenous carbon materials, improves the nitrate nitrogen assimilation of vegetable field soil, reduces the nitrogen leaching and soil N2O emission, and realizes the coordinated reduction and regulation of the pollution of vegetable field soil non-point source and N2O.The method is clear, simple, convenient, easy to implement.

Description

Technical Field

[0001] This invention belongs to the field of agricultural environmental protection methods, and in particular relates to a method for the synergistic reduction of non-point source pollution and nitrous oxide emissions from vegetable garden soil. Background Technology

[0002] Controlling the production and accumulation of nitrate nitrogen in vegetable garden soil is one of the key measures to reduce nitrogen loss. The process of reducing soil nitrate nitrogen concentration by increasing the nitrate nitrogen assimilation rate in vegetable garden soil has unique advantages. It converts nitrate nitrogen into microbial biomass nitrogen for short-term storage, which can then undergo remineralization, thus possessing nitrogen-retaining functions and being environmentally friendly.

[0003] Nitrate nitrogen assimilation is a crucial mechanism for reducing soil nitrate nitrogen concentration, mitigating nitrate nitrogen accumulation, and limiting its migration into water bodies via leaching or runoff. Enhanced nitrate nitrogen assimilation by soil microorganisms fosters competition for available carbon between heterotrophic and denitrifying microorganisms, ultimately reducing N2O emissions. However, current practices in vegetable cultivation often involve the application of organic fertilizers such as rapeseed cake and chicken manure, which have no significant impact on soil nitrate nitrogen assimilation rates. This hinders nitrate nitrogen assimilation in vegetable garden soils, as accumulated nitrate nitrogen is easily leached into groundwater and lost as N2O. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for the synergistic reduction of non-point source pollution and nitrous oxide emissions from vegetable garden soil. The method, based on the nitrate nitrogen content of the vegetable garden soil, optimizes the combination and ratio of different exogenous carbon materials to increase the amount of available carbon, reduce the application of nitrogen fertilizers, enhance the assimilation of nitrate nitrogen in the vegetable garden soil, and reduce soil N2O emissions, thereby achieving synergistic reduction and control of non-point source pollution and N2O emissions from vegetable garden soil. This method is technically clear, simple, convenient, and easy to implement.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for the synergistic reduction of non-point source pollution and nitrous oxide emissions from vegetable garden soil, comprising the following steps:

[0007] A mixture of base fertilizer and exogenous organic carbon is applied to the soil; the base fertilizer includes chemical fertilizer and animal manure; the exogenous organic carbon mixture includes agricultural waste and / or forestry waste; the mass ratio of the exogenous organic carbon mixture to animal manure is 0.8–1.25:1;

[0008] The carbon-to-nitrogen ratio of the exogenous organic carbon mixture is >25;

[0009] When the carbon-nitrogen ratio in the soil is <7, agricultural waste and / or forestry waste with a holocellulose mass percentage of 40%-50% and holocellulose mass percentage of >50% are selected and compounded to obtain the exogenous organic carbon mixture.

[0010] When the carbon-to-nitrogen ratio in the soil is ≥7, agricultural waste and / or forestry waste with a holocellulose mass percentage of <40% and 40%–50% are selected and compounded to obtain the exogenous organic carbon mixture.

[0011] Preferably, the mass ratio of nitrogen in the fertilizer to nitrogen in animal manure is 1:0.8-1.

[0012] Preferably, the animal excrement includes one or more of chicken manure, pig manure, and cow manure.

[0013] Preferably, the agricultural waste and / or forestry waste includes one or more of the following: crop straw, rice husks, rice bran, corn leaves, sawdust, pine needles, fallen leaves, and sugarcane bagasse.

[0014] Preferably, the crop straw includes one or more of corn straw, wheat straw, and rice straw.

[0015] Preferably, the soil includes soil used for growing vegetables.

[0016] Beneficial effects:

[0017] The method provided by this invention fully considers the carbon and nitrogen content, C / N ratio, and cellulose content of different exogenous carbon materials. Based on the nitrate nitrogen content of vegetable field soil, and while ensuring nitrogen supply to vegetables, it optimizes the combination and ratio of different exogenous carbon materials to increase the amount of available carbon and holocellulose content, reduce fertilizer nitrogen application, improve nitrate nitrogen assimilation in vegetable field soil, and reduce soil N2O emissions, thereby achieving synergistic emission reduction and control of non-point source pollution and N2O in vegetable field soil. This method is technically clear, simple, convenient, and easy to implement. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0019] Figure 1 Soil NO3 is generated from a mixture of traditional chemical fertilizers and chicken manure, and a mixture of chemical fertilizers, chicken manure, and organic materials. - -N curing rate results;

[0020] Figure 2 NO3 in vegetable garden soil - Results of the relationship between -N curing rate and holocellulose content in organic materials;

[0021] Figure 3 Soil NO3 after adding different organic materials to vegetable garden soil - -N content, NO3 - Results of N leaching and reduction in N2O emissions. Detailed Implementation

[0022] This invention provides a method for the synergistic reduction of non-point source pollution and nitrous oxide emissions from vegetable garden soil, comprising the following steps:

[0023] A mixture of base fertilizer and exogenous organic carbon is applied to the soil; the base fertilizer includes chemical fertilizer and animal manure; the exogenous organic carbon mixture includes agricultural waste and / or forestry waste; the mass ratio of the exogenous organic carbon mixture to animal manure is 0.8–1.25:1;

[0024] The carbon-to-nitrogen ratio of the exogenous organic carbon mixture is >25;

[0025] When the carbon-nitrogen ratio in the soil is <7, agricultural waste and / or forestry waste with a holocellulose mass percentage of 40%-50% and holocellulose mass percentage of >50% are selected and compounded to obtain the exogenous organic carbon mixture.

[0026] When the carbon-to-nitrogen ratio in the soil is ≥7, agricultural waste and / or forestry waste with a holocellulose mass percentage of <40% and 40%–50% are selected and compounded to obtain the exogenous organic carbon mixture.

[0027] In this invention, the mass ratio of nitrogen in the fertilizer to nitrogen in the animal manure is 1:0.8-1; the animal manure preferably includes one or more of chicken manure, pig manure, and cow manure; the agricultural waste and / or forestry waste preferably includes one or more of crop straw, rice husk, rice bran, corn leaves, sawdust, pine needles, fallen leaves, and sugarcane bagasse; the crop straw preferably includes one or more of corn straw, wheat straw, and rice straw; and the soil preferably includes soil used for growing vegetables.

[0028] The present invention preferably searches for keywords such as "organic fertilizer", "organic material", "exogenous carbon", "carbon", "nitrogen", "C / N" and "cellulose" in databases such as WebofScience and CNKI, and screens to obtain the C, N or C / N ratio and cellulose ratio of different exogenous carbon materials. The results are shown in Table 1.

[0029] Table 1. Carbon, nitrogen, and holocellulose content of commonly used exogenous carbon materials

[0030] rice husk 40.6 0.51 79.0 41.5 sawdust 52.7 0.13 403 52.4 rice bran 44.2 0.78 57.1 39.8 Corn leaves 44.6 1.32 33.9 46.0 corn stalks 48.9 1.10 44.0 49.6 wheat straw 45.0 0.30 150 43.7

[0031] Based on literature data or measured carbon and nitrogen content of organic materials, the C / N ratio of organic materials with various material proportions is calculated as follows:

[0032]

[0033] In Formula I, C / N is the C / N ratio of n types of exogenous carbon added to organic materials, W k Let P be the mass (g) of the k-th exogenous carbon material. C,k and P N,k , where are the C and N contents (%) of the k-th exogenous carbon material, and n is the number of types of exogenous carbon materials.

[0034] Based on literature data or measured organic cellulose content, the total cellulose content of organic materials in various material ratios is calculated as follows:

[0035]

[0036] In Formula II, H represents the holocellulose content (%) of n kinds of exogenous carbon-added organic materials, and W k Let H be the mass (g) of the k-th exogenous carbon material. k Let be the total cellulose content (%) of the k-th exogenous carbon material, and n be the number of types of exogenous carbon materials.

[0037] The nitrate nitrogen assimilation rate in dryland soils under exogenous carbon input increases with the amount of carbon source with a high C / N ratio and the content of holocellulose. Based on the nitrate content of vegetable garden soils, suitable exogenous carbon materials were selected, and the C / N ratio of mixtures with different gradations was determined. According to the principle that complex carbon sources such as straw can only improve nitrate nitrogen assimilation when their C / N ratio exceeds 25, exogenous carbon C / N ratios were divided into four levels: [25-50], [50-80], [80-110], and >110. When the C / N ratios of organic materials are similar, soils with higher holocellulose content have a higher nitrate nitrogen assimilation rate; holocellulose content was divided into three levels: <40%, 40%–50%, and >50%.

[0038] In this invention, the mass ratio of the exogenous organic carbon mixture to animal manure is 0.8–1.25:1. This ratio is beneficial for adjusting moisture content and carbon-nitrogen ratio, increasing organic matter content, and improving soil permeability; too low or too high a ratio is detrimental to microbial activity.

[0039] Currently, exogenous carbon additions to vegetable fields mostly involve the addition of single materials. Compared to other crops, nitrate nitrogen in vegetable field soils with high water and fertilizer content tends to accumulate easily, which exacerbates the risks of non-point source pollution and N2O emissions. This invention improves the soil's nitrate nitrogen assimilation capacity by combining different exogenous carbon materials in varying proportions. This transforms soil nitrate nitrogen into microbial biomass nitrogen for short-term storage, followed by remineralization, thus possessing nitrogen retention capabilities and reducing the risk of nitrogen loss into the environment. Based on the nitrate nitrogen content of vegetable field soil and the C / N ratio and cellulose content of the main exogenous carbon materials, this invention reduces fertilizer nitrogen application through the combination and proportioning of different exogenous carbon materials, thereby increasing soil nitrate nitrogen assimilation and reducing N2O emissions. This method not only achieves the goals of rational fertilization and reduced soil nitrate nitrogen accumulation in vegetable fields but also provides technical support for the prevention and control of non-point source pollution and the synergistic reduction of greenhouse gas emissions in vegetable field ecosystems.

[0040] This invention, while ensuring nitrogen supply to vegetables, increases the amount of available carbon and holocellulose content by optimizing the combination and ratio of different exogenous carbon materials, thereby reducing the amount of nitrogen applied by chemical fertilizers. Increasing the C / N ratio of organic materials will reduce the cumulative N2O emissions. For example, when straw with a relatively high C / N ratio is added, the soil microorganisms will assimilate the inorganic nitrogen in the soil, increasing the demand for nitrogen and thus reducing N2O emissions. On the other hand, straw with a relatively low C / N ratio decomposes faster, providing more substrate for nitrification and denitrification reactions, and thus generating more N2O emissions.

[0041] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, provides a method for the synergistic reduction of non-point source pollution and nitrous oxide emissions in vegetable garden soil, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] In greenhouse tomato cultivation on the North China Plain, the initial topsoil layer (0-30cm) had a C / N ratio of 6.5. Conventional treatment included using air-dried chicken manure as base fertilizer at the farmer's standard application rate of 200 kg N / hm² per season. 2 The fertilizer application rate is 230 kg N / hm² per season. 2 This is the standard usage for farmers. Nitrogen fertilizer is applied in the form of urea, at a rate of 230 kg N / hm² per season. 2 The phosphate fertilizer is superphosphate, and the application rate is 90 kg P2O5 / hm² per season. 2 The potassium fertilizer is potassium sulfate, and the application rate is 650 kg K₂O / hm. 2The organic materials included wheat straw, corn straw, rice husks, and corn leaves. Rice husks contained 38.5% C and 0.50% N, corn leaves 45.0% C and 1.15% N, corn straw 37.4% C and 1.05% N, and wheat straw 45% C and 0.4% N. The mixture was added at 1.1 times the weight of chicken manure. Materials with a C / N ratio of 30-40 consisted of a mixture of 10% corn leaves and 90% corn straw (total cellulose content 49.2%), materials with a C / N ratio of 70-80 consisted of 95% rice husks and 5% wheat straw (total cellulose content 41.6%), and materials with a C / N ratio >110 consisted of 95% wheat straw and 5% rice husks (total cellulose content 43.6%). Soil N2O emission flux was determined throughout the growing season using a static chamber-gas chromatography method. Measurements were taken every 1-2 days for the first week after fertilization, and then weekly thereafter. Soil samples were collected after crop harvest to determine soil NO3 levels. - -N content. Soil NO3 was calculated using indoor culture, isotope labeling, and mathematical modeling methods. - -N curing rate. NO3 was determined using the leaching pool method. - -N leaching amount.

[0044] from Figure 1 It can be seen that after implementing this method, compared with the traditional treatment of chemical fertilizer + chicken manure, the soil NO3 decreased by 30-40 after adding organic materials C / N. - The N-solidification rate is 1 mgN / gC. After adding organic materials, the C / N ratio of soil NO3 is 70-80. - The nitrogen solidification rate was 0.4 mgN / gC. After adding organic materials with a C / N ratio > 100, soil NO3 levels decreased. - The curing rate of -N is 1.36 mgN / gC.

[0045] from Figure 2 It can be seen that with the increase of cellulose content in organic materials, soil NO3... - -N curing rate increases.

[0046] from Figure 3 It can be seen that, compared with conventional treatment, adding organic materials with a C / N ratio of 30-40 can reduce soil NO3. - -N content, soil NO3 - -N content decreased by 3.51 g / kgC, and the added organic material C / N ratio was 70-80, resulting in soil NO3. - -N content decreased by 16.5 g / kgC. Adding organic materials resulted in a C / N ratio of 30-40, which reduced NO3 in the vegetable garden. - -N leaching can reduce NO3 in vegetable fields by 0.69 g / kgC. Adding organic materials with a C / N ratio of 70-80 can reduce NO3 in vegetable fields. --N leaching can be reduced by 1.15 g / kgC. Adding organic materials with a C / N ratio of 30-40 can reduce N2O emissions by 0.27 g / kgC, and adding organic materials with a C / N ratio of 78-80 can reduce N2O emissions by 2.02 g / kgC.

[0047] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for synergistic reduction of non-point source pollution and nitrous oxide emissions from vegetable garden soil, characterized in that, Includes the following steps: A mixture of base fertilizer and exogenous organic carbon is applied to the soil for vegetable cultivation. The base fertilizer includes chemical fertilizer and animal manure. The mass ratio of nitrogen in the chemical fertilizer to nitrogen in the animal manure is 1:0.8-1. The animal manure includes one or more of chicken manure, pig manure, and cow manure. The exogenous organic carbon mixture includes agricultural waste and / or forestry waste. The carbon-nitrogen ratio of the exogenous organic carbon mixture is >25. The mass ratio of the exogenous organic carbon mixture to animal manure is 0.8-1.25:

1. The agricultural waste and / or forestry waste includes one or more of crop straw, rice husks, rice bran, corn leaves, sawdust, pine needles, fallen leaves, and sugarcane bagasse. The crop straw includes one or more of corn straw, wheat straw, and rice straw. When the carbon-nitrogen ratio in the soil is <7, agricultural waste and / or forestry waste with a holocellulose mass percentage of 40%~50% and holocellulose mass percentage >50% are selected and compounded to obtain the exogenous organic carbon mixture. When the carbon-to-nitrogen ratio in the soil is ≥7, agricultural waste and / or forestry waste with a holocellulose mass percentage of <40% and 40%~50% are selected and compounded to obtain the exogenous organic carbon mixture.

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