A method for dividing urea fertilizer domain

Abstract

The present invention relates to the technical field of fertilizer domain division, and in particular to a method for dividing urea fertilizer domains. The method first enlarges the fertilizer domain by forming urea granules into large particles. The method then divides the fertilizer domain into three parts, namely, the near fertilizer domain, the middle fertilizer domain, and the far fertilizer domain, based on the variation patterns of the ammonia-oxidizing bacteria copy number and diversity index in different regions during urea diffusion. This method provides a theoretical basis for developing new urea efficiency-enhancing products.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizer domain division, and in particular to a method for dividing a urea fertilizer domain. Background Art

[0002] Once applied to the soil, urea is easily broken down by urease and lost through ammonia volatilization, nitrification-denitrification, leaching, and runoff, resulting in reduced urea utilization and environmental pollution. The urea fertilizer domain is the area within which urea interacts with the soil after urea granules enter the soil. The size of this domain, as well as the dissolution, movement, and transformation processes of urea granules over time and space, and their nutrient concentrations, are influenced by soil properties, moisture, temperature, and soil microbial and enzyme activity. The urea concentration and biological characteristics of the soil solution within the fertilizer domain vary significantly at different distances from the urea granules, directly impacting the supply and effective utilization of soil nitrogen.

[0003] Generally speaking, the fertilizer nutrient concentration in the soil close to the fertilization point is several times or even dozens of times that of the entire soil, and the nitrogen conversion process therein is also significantly different from that in the general soil. + -N content is relatively high. At this time, NO2 - -N to NO3 - -N conversion is blocked, and the generated NO3 - -N is converted into NO2 under the action of denitrification - -N, leading to NO2 in fertilizer field - -N exists as the main nitrogen form; at the same time, the higher pH in this environment is not conducive to the survival of microorganisms, free ammonia and NO2 - The increase in -N content will also have a toxic effect on microorganisms, resulting in a decrease in the activity of microorganisms such as ammonia oxidizing bacteria. As urea gradually diffuses outward, the nutrient concentration gradually decreases and the activity of microorganisms gradually increases.

[0004] The interaction between different fertilizers and soils is related to the fertilizer's characteristics, resulting in significant differences in fertility domains. For phosphate fertilizers, phosphorus has poor mobility and is easily absorbed and fixed, resulting in a small fertility domain. Urea, on the other hand, is highly mobile in soil and has a large fertility domain. The urea conversion process and mechanisms vary significantly across regions, but currently there is a lack of methods and evidence for delineating different urea fertility domains. Summary of the Invention

[0005] To address these issues, the present invention provides a method for dividing urea fertilizer domains. This method divides the fertilizer domain into three parts: the near fertilizer domain, the middle fertilizer domain, and the far fertilizer domain, based on the variation in the copy number and diversity index of ammonia-oxidizing bacteria in different regions during urea diffusion. This method provides a theoretical basis for developing new urea efficiency-enhancing products.

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

[0007] The present invention provides a method for dividing a urea fertilizer domain, comprising the following steps:

[0008] Urea is made into urea granules with a radius of 1 cm and then pressed into the soil until the surface of the urea granules is flush with the upper surface of the soil, and then the exposed surface of the urea granules is covered with soil;

[0009] After 5 days of cultivation, circular sampling was performed with the center of the urea granule as the starting point and every 1 / 2 radius of the urea granule, and the copy number and diversity index of ammonia oxidizing bacteria in different circular samples were measured;

[0010] Taking the change in the copy number or diversity index of the ammonia oxidizing bacteria as the dependent variable and the distance between the microdomains as the independent variable, the equation can be obtained as shown in Formula I:

[0011] Y=aX 2 +bX+c Formula Ⅰ;

[0012] Y is the copy number or diversity index of ammonia-oxidizing bacteria;

[0013] X is the micro-domain distance, X>0, a<0;

[0014] The number of ammonia oxidizing bacteria copies on day 0 of culture is recorded as Y 11 The diversity index of culture day 0 is recorded as Y 12 The ammonia oxidizing bacteria copy number at the peak on the 5th day of culture is recorded as Y 21 The diversity index at the peak on the 5th day of culture is recorded as Y 22 , then the endpoint values ​​of the near, middle and far fertilizer ranges can be expressed as:

[0015] Near the fat area:

[0016] or

[0017] Zhongfei area:

[0018] or

[0019] Far Fertile Area:

[0020] or

[0021] When X 11 and X 12 If they are different, the smaller value shall prevail in the demarcation range of the near-fertile area;

[0022] When X 21 and X22 If they are different, the smaller value shall prevail in the demarcation of the medium-fat area;

[0023] When X 31 and X 32 If they are different, the smaller value shall prevail in the demarcation of the far fertilizer area.

[0024] Preferably, the culturing environment temperature is 20°C to 25°C.

[0025] Preferably, the thickness of the covering soil is 1 to 2 mm.

[0026] Preferably, the bulk density of the soil is 1.1 to 1.3 g·cm 3 , the soil moisture content is 15% to 25%.

[0027] Beneficial effects:

[0028] The present invention firstly makes urea granules into large particles, thereby amplifying the fertilizer area, and then divides the fertilizer area into three parts according to the change rules of the copy number and diversity index of ammonia oxidizing bacteria in different areas during the urea diffusion process, namely the near fertilizer area, the middle fertilizer area and the far fertilizer area ( Figure 2 ), providing a theoretical basis for the development of new urea efficiency-enhancing products. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below.

[0030] Figure 1 This is a schematic diagram of the urea fertilizer domain;

[0031] Figure 2 Schematic diagram of the near, middle and far fertile areas of urea; a: near fertile area; b: middle fertile area; c: far fertile area; d: non-fertile area;

[0032] Figure 3 This is a schematic diagram of the urea fertilizer domain division experiment;

[0033] Figure 4 It is the main attempt of the experiment on urea fertilizer domain division;

[0034] Figure 5 This is a schematic diagram of sampling different fertilizer areas of urea;

[0035] Figure 6 This is the relationship between the copy number of ammonia-oxidizing bacteria and the distance between the fertilizer microdomains on the 5th day of culture;

[0036] Figure 7 This is the relationship between the diversity index of ammonia-oxidizing bacteria (Chao1) and the distance between fertilizer microdomains on the 5th day of cultivation. DETAILED DESCRIPTION

[0037] The present invention provides a method for dividing a urea fertilizer domain, comprising the following steps:

[0038] Urea is made into urea granules with a radius of 1 cm and then pressed into the soil until the surface of the urea granules is flush with the upper surface of the soil, and then the exposed surface of the urea granules is covered with soil;

[0039] After 5 days of cultivation, circular sampling was performed with the center of the urea granule as the starting point and every 1 / 2 radius of the urea granule, and the copy number and diversity index of ammonia oxidizing bacteria in different circular samples were measured;

[0040] Taking the change in the copy number or diversity index of the ammonia oxidizing bacteria as the dependent variable and the distance between the microdomains as the independent variable, the equation can be obtained as shown in Formula I:

[0041] Y=aX 2 +bX+c Formula Ⅰ;

[0042] Y is the copy number or diversity index of ammonia-oxidizing bacteria;

[0043] X is the micro-domain distance, X>0, a<0;

[0044] The number of ammonia oxidizing bacteria copies on day 0 of culture is recorded as Y 11 The diversity index of culture day 0 is recorded as Y 12 The ammonia oxidizing bacteria copy number at the peak on the 5th day of culture is recorded as Y 21 The diversity index at the peak on the 5th day of culture is recorded as Y 22 , then the endpoint values ​​of the near, middle and far fertilizer ranges can be expressed as:

[0045] Near the fat area:

[0046] or

[0047] Zhongfei area:

[0048] or

[0049] Far Fertile Area:

[0050] or

[0051] When X 11 and X 12 If they are different, the smaller value shall prevail in the demarcation range of the near-fertile area;

[0052] When X 21 and X 22 If they are different, the smaller value shall prevail in the demarcation of the medium-fat area;

[0053] When X 31 and X 32 If they are different, the smaller value shall prevail in the demarcation of the far fertilizer area.

[0054] In the present invention, the cultivation environment temperature is preferably 20°C to 25°C, more preferably 25°C; the thickness of the covering soil is preferably 1 to 2 mm; the bulk density of the soil is preferably 1.1 to 1.3 g·cm 3 , more preferably 1.2 g·cm 3 , the soil moisture content is preferably 15% to 25%, more preferably 20%.

[0055] The number of ammonia oxidizing bacteria copies cultured on day 0 of the present invention is recorded as Y 11 The diversity index of culture day 0 is recorded as Y 12 The number of ammonia oxidizing bacteria copies at the peak (maximum value) on the 5th day of culture is recorded as Y 21 The diversity index at the peak on the 5th day of culture is recorded as Y 22 , that is, the ammonia oxidizing bacteria copy number or diversity index of the soil without urea granules is recorded as Y 11 and Y 12 .

[0056] In the preliminary experiments of the present invention, it was found that urea was completely decomposed after the 5th day of culture, mainly in the form of ammonium nitrogen and nitrate nitrogen. The process of urea hydrolysis and conversion into ammonium nitrogen has ended, and the ammonium nitrogen content in the near-fertilizer domain no longer increases, and the inhibitory effect on the copy number and diversity index of ammonia oxidizing bacteria no longer increases. Therefore, the present invention takes the data of the last day of culture (the 5th day) as an example, and finds that the range of different fertilizer micro-domains can be accurately divided according to the ammonia oxidizing bacteria copy number and diversity index indicators. The fertilizer domain division method for other time periods can also be divided according to the ammonia oxidizing bacteria copy number and diversity index.

[0057] Studies have shown that in high-efficiency urea products containing synergistic substances, the migration speed of different synergistic substances is inconsistent with the movement of urea, resulting in different performance of synergistic substances at different distances from the fertilization point, which in turn affects the nutrient conversion within different urea fertilizer domains. The present invention first makes urea granules into large particles, thereby amplifying the fertilizer domain. Based on the changes in the copy number and diversity index of ammonia-oxidizing bacteria in different regions during the urea diffusion process, the fertilizer domain is divided into three parts: the near fertilizer domain, the middle fertilizer domain, and the far fertilizer domain, respectively. This provides a theoretical basis for the development of new urea synergistic products.

[0058] Among them, the fertilizer area: the fertilizer nutrient concentration in this area is several times or even dozens of times that of the entire soil, and the nitrogen conversion process in it is also significantly different from that in general soil. The soil pH and NH4 +-N content is high, which is not conducive to the survival of ammonia oxidizing bacteria, resulting in a low copy number and diversity index of ammonia oxidizing bacteria.

[0059] Middle fertile area: Compared with the near fertile area, the urea concentration in this area decreased, but the copy number and diversity index of ammonia oxidizing bacteria gradually increased to a peak value (Y 21 or Y 22 ) begins to decrease slowly, and when the number of ammonia oxidizing bacteria copies decreases to 1 / 2 (Y 11 +Y 21 ) or the diversity index dropped to 1 / 2 (Y 12 +Y 22 ), the present invention defines the diffusion distance corresponding to this value as the boundary of the middle fat region.

[0060] Far-fertile area: Compared with the medium-fertile area, the soil nutrient concentration, pH, ammonia-oxidizing bacteria copy number and diversity index in this area gradually decreased, which was consistent with the entire soil body.

[0061] To further illustrate the present invention, a method for dividing a urea fertilizer domain provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0062] Example 1

[0063] Experimental design: Urea was squeezed into granules (1 cm radius) and placed at the center of a disk (10 cm radius) filled with soil. Specifically, the urea granules were placed on soil at a height of 4 cm. The urea granules were gently pressed into the soil until the surface of the urea granules was flush with the upper surface of the soil. The surface of the urea granules was covered with soil with a thickness of 1 to 2 mm ( Figure 3 and Figure 4 ); the bulk density of the soil is 1.2g·cm 3 , soil moisture content 20%, ambient temperature 25℃.

[0064] Sample collection: Circular sampling is carried out every 0.5 mm (1 / 2 of the radius of urea particles) from the fertilizer point. Figure 5 ), samples were taken at 10 minutes, 30 minutes, 1 hour, 2 hours, 6 hours, 12 hours, 1 day, 3 days and 5 days after culture, and each treatment was repeated 3 times, that is, 27 culture dishes, 3 samples were taken in each time period, and all rings were sampled.

[0065] Measurement indicators: ammonia oxidizing bacteria copy number and ammonia oxidizing bacteria diversity index. The measurement method can be found in the literature [Liang Cheng, Xiaoqin Chen, Dianjun Lu, Huoyan Wang. Long-acting mechanisms of concentrated urea application-High urea concentrations are biological inhibitors[J]. Applied Soil Ecology, 2023, 182: 104723.].

[0066] Calculation method of near, middle and far fat region boundaries

[0067] Based on the boundary division of the near, middle, and far fertility domains, the changes in the copy number and diversity index of ammonia-oxidizing bacteria within the three fertility domains show a trend of first increasing and then decreasing, with activity reaching its highest level in the middle fertility domain. With the distance to the near and far fertility domains as the left and right boundaries of the function, the changes in the copy number and diversity index of ammonia-oxidizing bacteria and the change in the interfertility distance satisfy a quadratic equation. With the change in the copy number or diversity index of ammonia-oxidizing bacteria as the dependent variable and the distance to the interfertility microdomain as the independent variable, the equation is shown in Equation I:

[0068] Y=aX 2 +bX+c Formula Ⅰ;

[0069] Y is the copy number of ammonia-oxidizing bacteria or the diversity index of ammonia-oxidizing bacteria;

[0070] X is the micro-domain distance, X>0, a<0;

[0071] If the number of ammonia oxidizing bacteria copies on day 0 of culture is denoted as Y 11 The diversity index of culture day 0 is recorded as Y 12 The ammonia oxidizing bacteria copy number at the peak on the 5th day of culture is recorded as Y 21 The diversity index at the peak on the 5th day of culture is recorded as Y 22 , then the endpoint values ​​of the near, middle and far fertilizer ranges can be expressed as:

[0072] Near the fat area:

[0073] or

[0074] Zhongfei area:

[0075] or

[0076] Far Fertile Area:

[0077] or

[0078] When X 11 and X 12 If they are different, the smaller value shall prevail in the demarcation range of the near-fertile area;

[0079] When X 21 and X 22 If they are different, the smaller value shall prevail in the demarcation of the medium-fat area;

[0080] When X 31 and X 32 If they are different, the smaller value shall prevail in the demarcation of the far fertilizer area.

[0081] Measurement results

[0082] Relationship between the copy number of ammonia-oxidizing bacteria and the distance between manure microdomains

[0083] Taking the copy number of ammonia oxidizing bacteria and the distance between fertilizer microdomains on the 5th day of culture as an example, the relationship between the changes is as follows: Figure 6 As shown, within the range of 0 to 1.5 cm from the fertilizer point, the copy number of ammonia-oxidizing bacteria is low, and this distance is the near-fertilization range (0 to 1.5 cm); within the range of 1.5 to 5.3 cm from the fertilizer point, the copy number of ammonia-oxidizing bacteria first gradually increases and then gradually decreases to the peak value and the average of the copy number of ammonia-oxidizing bacteria in the non-fertilization range, and this distance is the medium-fertilization range (1.5 to 5.3 cm); at a distance of 5.3 to 6.5 cm from the fertilizer point, the copy number of ammonia-oxidizing bacteria gradually decreases. At a distance of 6.5 cm from the fertilizer point, the copy number of ammonia-oxidizing bacteria is consistent with that of the entire soil, indicating that the distance of 6.5 cm from the fertilizer point is the boundary of the fertilizer microdomain. A binomial equation fitting of the change in the copy number of ammonia-oxidizing bacteria and the distance from the fertilizer microdomain found that the copy number of ammonia-oxidizing bacteria and the distance from the fertilizer microdomain satisfy the following equation:

[0084] y=-2.06x 2 +16.34x-18.22, where x is the microdomain distance and y is the copy number of ammonia-oxidizing bacteria.

[0085] Relationship between the diversity index of ammonia-oxidizing bacteria (Chao1) and the distance between fertilizer microdomains

[0086] Taking the ammonia oxidizing bacteria diversity index (Chao1) and the distance between fertilizer microdomains on the 5th day of cultivation as an example, the relationship between the changes is as follows: Figure 7As shown, within the range of 0 to 1.5 cm from the fertilizer point, the ammonia oxidizing bacteria diversity index (Chao1) is low, and this distance is the near-fertilization range (0-1.5 cm). Within the range of 1.5 to 5.6 cm from the fertilizer point, the ammonia oxidizing bacteria diversity index (Chao1) first gradually increases and then gradually decreases to a peak value and the average of the ammonia oxidizing bacteria diversity index in the non-fertilization range, and this distance is the mid-fertilization range (1.5-5.6 cm). The ammonia oxidizing bacteria diversity index (Chao1) gradually decreases at a distance of 5.6 to 6.5 cm from the fertilizer point. At a distance of 6.5 cm from the fertilizer point, the ammonia oxidizing bacteria diversity index (Chao1) is consistent with the entire soil, indicating that the distance of 6.5 cm from the fertilizer point is the boundary of the fertilizer microdomain. A binomial equation fitting of the ammonia oxidizing bacteria diversity index (Chao1) and the distance from the fertilizer microdomain found that the ammonia oxidizing bacteria diversity index (Chao1) and the distance from the fertilizer microdomain satisfy the following equation:

[0087] y=-310x 2 +2473x+104, where x is the microdomain distance and y is the ammonia-oxidizing bacteria diversity index (Chao1).

[0088] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for dividing a urea fertilizer domain, characterized in that: The following steps are involved: Urea is made into urea granules with a radius of 1 cm and then pressed into the soil until the surface of the urea granules is flush with the upper surface of the soil, and then the exposed surface of the urea granules is covered with soil; After 5 days of culture, circular sampling was performed with the center of the urea granule as the starting point and every 1 / 2 radius of the urea granule, and the copy number and diversity index of ammonia oxidizing bacteria in different circular samples were measured; Taking the change in the copy number or diversity index of the ammonia oxidizing bacteria as the dependent variable and the distance between the microdomains as the independent variable, the equation is as shown in Formula I: Y=aX 2 +bX+c Formula Ⅰ; Y is the copy number or diversity index of ammonia-oxidizing bacteria; X is the micro-domain distance, X>0, a<0; The number of ammonia oxidizing bacteria copies on day 0 of culture is recorded as Y 11 The diversity index of culture day 0 is recorded as Y 12 The ammonia oxidizing bacteria copy number at the peak on the 5th day of culture is recorded as Y 21 The diversity index at the peak on the 5th day of culture is recorded as Y 22 , then the endpoint values ​​of the near, middle and far fertilizer ranges can be expressed as: Near the fat area: Formula II, or Formula III; Zhongfei area: Formula IV, or Formula V; Far Fertile Area: Formula VI, or Formula VII; When X 11 and X 12 If they are different, the smaller value shall prevail in the demarcation range of the near-fertile area; When X 21 and X 22 If they are different, the smaller value shall prevail in the demarcation of the medium-fat area; When X 31 and X 32 If they are different, the smaller value shall be used as the basis for the demarcation of the far-field area.

2. The division method according to claim 1, characterized in that: The culturing environment temperature is 20°C to 25°C.

3. The division method according to claim 1, characterized in that: The thickness of the covering soil is 1-2 mm.

4. The division method according to claim 1, characterized in that: The bulk density of the soil is 1.1-1.3 g·cm 3 , the soil moisture content is 15%~25%.

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