Simplified corn nitrogen fertilizer dosage recommendation method based on nitrogen balance standard

Abstract

The invention discloses a light and simplified corn nitrogen fertilizer dosage recommendation method based on a nitrogen balance standard, and relates to the technical field of agricultural resource environment. According to the corn nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard, the nitrogen fertilizer dosage can be recommended only by knowing the corn yield and the soil fertility grade, the surplus of nitrogen in soil can be reduced to the maximum extent on the basis of ensuring the crop yield, the environmental loss of active nitrogen is further reduced, and the crop yield is improved. Therefore, high-yield, high-efficiency, sustainable and healthy development of agriculture is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural resources and environment, and in particular to a lightly simplified method for recommending nitrogen fertilizer dosage for corn based on a nitrogen balance standard. Background Art

[0002] Corn has a very high planting area and total yield among food crops. A large amount of nitrogen fertilizer is consumed during corn planting. However, overall, nitrogen fertilizer is applied excessively during corn planting. Excessive application of nitrogen fertilizer leads to increased ammonia volatilization, leaching and runoff losses, exacerbating problems such as air and water pollution.

[0003] At present, the method for recommending the amount of nitrogen fertilizer for crops is mainly developed based on one or more of soil nutrient testing, fertilizer effect function, crop or soil model. However, most small farmers' business models do not have the conditions for soil testing and fertilization or other scientific fertilization. Especially in summer corn, the interval between the harvest of the previous crop and the sowing of summer corn is short, resulting in the failure to provide soil testing and analysis results in a timely manner, and it is impossible to carry out soil testing and formula fertilization. Therefore, a large number of farmers mainly fertilize according to experience, and unreasonable fertilization is relatively common. The development of a recommended fertilization technology that is both scientific and reasonable and simple and fast is an urgent need to promote scientific fertilization of corn. Summary of the invention

[0004] The purpose of the present invention is to provide a lightly simplified method for recommending nitrogen fertilizer dosage for corn based on nitrogen balance standard, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for recommending nitrogen fertilizer dosage for corn based on nitrogen balance standard, comprising the following steps:

[0007] Step 1): Identify the soil fertility level of cultivated land: In nitrogen fertilizer recommendations, soil fertility is mainly reflected in the soil's nitrogen supply capacity.

[0008] The present invention provides four methods for determining the soil nitrogen supply level:

[0009] Method 1: Determine based on the nitrogen absorption of the aboveground part of corn without nitrogen fertilizer application in the target plot. The present invention collects and summarizes the fertilization field test data conducted in the main corn producing areas in China and establishes a database. The first 25%, middle 25%-75%, and bottom 25% of the nitrogen absorption data set of the aboveground part of corn without nitrogen fertilizer application in the database (1315 samples) are used as the classification criteria for high, medium, and low levels of nitrogen supply in cultivated land soil (Table 1);

[0010] Method 2: Determine based on the corn yield of the target plot without nitrogen fertilizer. Based on the database of Method 1, the first 25%, middle 25%-75%, and bottom 25% of the corn yield data set without nitrogen fertilizer were used as the classification criteria for high, medium, and low levels of soil nitrogen supply in cultivated land (Table 2);

[0011] Method 3: If the target plot has soil test results, it is divided according to the soil organic matter content (Table 3); specifically:

[0012] The soil nitrogen supply level is based on the soil organic matter content level, and the soil hydrolyzable nitrogen is used as the adjustment factor: when the soil hydrolyzable nitrogen is ≥180 mg / kg, the low supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity; when the soil hydrolyzable nitrogen is ≤100 mg / kg, the high supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity;

[0013] Method 4: Determine based on the apparent properties of the target plot’s soil, such as texture and color (Table 4).

[0014] Table 1

[0015]

[0016] Table 2

[0017]

[0018] Table 3

[0019]

[0020] Table 4

[0021]

[0022]

[0023] Step 2): Determine the nitrogen balance standard of the target plot. Based on the above database, the present invention establishes the relationship between the nitrogen yield response (i.e., the corn yield increment of the target plot treated with nitrogen fertilizer compared to that of the target plot treated with no nitrogen fertilizer) and the apparent nitrogen balance of the soil (i.e., the difference between the amount of nitrogen applied and the amount of corn absorbed and removed). On the basis of ensuring corn yield and minimizing nitrogen surplus in the soil, the maximum economic benefit algorithm is used to propose nitrogen balance standards under high, medium and low soil nitrogen supply levels. At the same time, the present invention compares the differences in soil apparent nitrogen balance between conventional nitrogen fertilizer application and fertilization modes such as slow-release nitrogen fertilizer, deep mechanical nitrogen fertilizer application, organic fertilizer application, and straw return to the field, and then proposes a reference standard for nitrogen balance in different fertilization modes (Table 5). According to the soil nitrogen supply level and nitrogen fertilizer application mode identified in step 1, refer to Table 5 to determine the nitrogen balance standard of the target plot.

[0024] According to the soil nitrogen supply level and nitrogen fertilizer application pattern identified in step 1), refer to Table 5 to determine the nitrogen balance standard of the target plot.

[0025] Table 5

[0026]

[0027] Step 3) Determine the nitrogen uptake of corn plants in the target plot:

[0028] The nitrogen absorption of the aboveground part of corn plants takes into account the nitrogen absorption of grains and the nitrogen absorption of straw, which can be calculated by formula (1):

[0029] N uptake = N grain + N straw = Y grain * X grain + Y straw * X straw (1)

[0030] Among them, N uptake 、N grain 、N straw represents the nitrogen absorption of the aboveground part, the nitrogen absorption of corn kernels and the nitrogen absorption of corn stalks of the target plot (kg N / ha); Y grain and Y straw represent corn grain yield and corn stover biomass (kg / ha), respectively; X grain and X straw They represent the nitrogen content of corn kernels and corn stover (mg / kg), respectively.

[0031] Specifically, Y grain Determined based on the average corn yield of the target plot in the past 3-5 years without biological stress.

[0032] Y straw If there is no measured data, the following formula (2) can be used to obtain:

[0033] Y straw =Y grain * a (2)

[0034] Where a represents the conversion coefficient between corn grain yield and corn stover biomass, and the reference value is shown in Table 6.

[0035] X grain If there is no measured data, then N grain By formula (3), we can obtain:

[0036] N grain= Y grain * b * 0.001 (3)

[0037] Wherein, b represents the conversion coefficient between corn grain yield and corn grain nitrogen absorption. The reference value is shown in Table 6.

[0038] X straw If there is no measured data, then N straw By formula (4), we can obtain:

[0039] N straw = Y straw * c * 0.001 (4)

[0040] Wherein, c represents the conversion coefficient between corn straw biomass and corn straw nitrogen absorption, and the reference value is shown in Table 6.

[0041] Table 6

[0042] Conversion Factor Spring corn Summer corn a 1.08 0.95 b 10.7 11.9 c 5.6 7.5

[0043] Step 4) Calculate the amount of nitrogen fertilizer for corn in the target plot: predict the recommended amount of nitrogen fertilizer based on the nitrogen absorption of the aboveground part of corn in the target plot and the nitrogen balance standard of cultivated land, which can be obtained by formula (5):

[0044] N=N uptake +N balance (5)

[0045] Wherein, N represents the recommended amount of nitrogen fertilizer for the target plot (kg N / ha); uptake represents the aboveground nitrogen absorption of corn in the target plot (kg N / ha), obtained in step 3); N balance represents the nitrogen balance standard (kg N / ha) of the target plot, obtained by steps 1) and 2).

[0046] The nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard of the present invention is a simplified recommendation method, which can be used with or without soil test results. Ordinary agricultural technicians at the grassroots level or farmers with certain scientific knowledge reserves only need to understand the corn yield level of the target plot, identify the soil fertility level, and then go through a simple calculation process to achieve scientific and reasonable nitrogen fertilizer recommendations. Compared with the prior art, it is more suitable for corn planting areas where soil testing is not timely, soil testing formula fertilization is not available, or other fertilization technical conditions that require professional testing equipment and personnel are not available.

[0047] Compared with the prior art which only formulates application methods for conventional nitrogen fertilizer products, the present invention not only proposes standard parameters of nitrogen balance based on conventional nitrogen fertilizer products and fertilization technology, but also calibrates parameters for efficient fertilization scenarios such as slow-release fertilizers, mechanical deep application of nitrogen fertilizers, application of organic fertilizers, and returning straw to the field, which is more suitable for the current diversified corn nitrogen fertilizer application scenarios.

[0048] Compared with traditional technologies that mostly directly use corn yield and nitrogen fertilizer application amount to establish a fertilizer effect function and then propose relevant fertilization parameters, the present invention uses yield response and nitrogen balance as indicators to establish a function model. This is because these two indicators are indirect indicators. The yield response is the increase in yield of the nitrogen treatment relative to the non-nitrogen treatment, and the yield of the non-nitrogen treatment represents the soil fertility level of the plot. Therefore, the deviation of recommended fertilization parameters caused by differences in soil fertility levels at different test points is eliminated to the greatest extent; compared with traditional technologies, the nitrogen fertilizer application amount determined based on the fertilizer effect function is only applicable to the field scale, and the nitrogen balance is the difference between the nitrogen application amount and the nitrogen absorption amount of the crop. Therefore, the nitrogen balance standard proposed in the present invention can realize dynamic decision-making on nitrogen fertilizer application amount according to the difference in nitrogen absorption amount of the crop, and is more suitable for the regional scale.

[0049] The present invention generates relevant nitrogen fertilizer recommendation parameters based on field test big data rather than on individual or a few test results, and has broad representativeness.

[0050] The present invention discloses the following technical effects:

[0051] The present invention proposes a method for recommending nitrogen fertilizer dosage for corn based on the nitrogen balance standard. This method only requires understanding of corn yield and soil fertility level to recommend nitrogen fertilizer dosage. It can minimize nitrogen surplus in the soil to the greatest extent while ensuring crop yield, thereby reducing the environmental loss of active nitrogen, thereby promoting high-yield, efficient, sustainable and healthy development of agriculture. DETAILED DESCRIPTION

[0052] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0053] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0054] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0055] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0056] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0057] Example 1

[0058] In order to verify the feasibility of applying the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard to corn, the present invention uses a large amount of field test data from different corn planting season types to carry out recommended fertilization practices, and compares the recommended results with the local farmers' habitual fertilization and other widely recognized scientific fertilization methods to verify whether the recommended results are reasonable.

[0059] Field trials were conducted in 124 test plots from 2017 to 2020 in the main spring corn producing provinces of Heilongjiang, Jilin, Inner Mongolia, and the main summer corn producing provinces of Hebei and Shanxi. The recommended method for nitrogen fertilizer application based on the nitrogen balance standard was verified. The number of trials and regions for verifying different fertilization methods are shown in Table 7. According to the nitrogen absorption of the aboveground part of corn without nitrogen fertilizer in each test plot (Table 7), the standard provided in Table 1 was used to determine the soil nitrogen supply level of the plot (Table 7). According to the fertilization method and soil nitrogen supply level of each test plot, the standard provided in Table 5 was used to determine the nitrogen balance standard of the plot (Table 8). The measured value of the highest nitrogen uptake by the upper part of the jade in all treatments was used as the target nitrogen uptake. The recommended nitrogen fertilizer dosage (OPT) for the plot was predicted using formula (5) and compared with the local farmers' habitual nitrogen fertilizer dosage (FP), the nitrogen fertilizer dosage recommended by local soil testing formula fertilization (ST), and the nitrogen fertilizer dosage recommended by the nutrient expert method (NE) based on the same plot (Table 8).

[0060] Table 7

[0061]

[0062] Table 8

[0063]

[0064] Table 8 summarizes the nitrogen requirements of corn and the recommended dosage of the four fertilization methods for different corn planting season types and different soil fertility levels. The results show that: in all plots of spring corn, the average dosage of OPT nitrogen fertilizer is 220kg N / ha, which is 6.4% lower than the average dosage of FP nitrogen fertilizer, and 8.6% to 13.1% higher than the recommended results of ST and NE. This is because in low-fertility soil, due to the low soil background nitrogen supply capacity, this method requires a higher amount of exogenous nitrogen fertilizer to ensure the yield level; in all plots of summer corn, the average dosage of OPT nitrogen fertilizer is 185kg N / ha, and its recommended value is basically the median recommended value of ST and NE methods, and it is 20.8% lower than the average dosage of FP nitrogen fertilizer.

[0065] In general, the method for recommending nitrogen fertilizer dosage based on the nitrogen balance standard proposed in the present invention can significantly reduce the current nitrogen fertilizer dosage that farmers are accustomed to, and achieve the purpose of reducing nitrogen fertilizer and increasing efficiency. The recommended results deviate from the two scientific fertilization methods ST and NE, mainly due to the difference in the recommendation principles, but are basically within the upper and lower ranges of the recommended values ​​of the two methods, indicating that the recommended amount is basically reasonable. Therefore, the field verification test results show that the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard proposed in the present invention can be used for nitrogen fertilizer dosage decision-making for corn.

[0066] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A simplified method for recommending the amount of nitrogen fertilizer for corn based on the nitrogen balance standard, characterized in that: The following steps are involved: (1) Use any of the methods 1 to 4 to determine the soil nitrogen supply level of the target plot: Method 1: According to different corn varieties, the soil nitrogen supply level of the target plot is determined based on the nitrogen absorption of the aboveground part of the corn without nitrogen fertilizer: Method 2: According to different corn varieties, determine the soil nitrogen supply level of the target plot based on the corn yield without nitrogen fertilizer: Method 3: Classify the soil nitrogen supply level of the target plot according to the soil organic matter content: The soil nitrogen supply level is based on the soil organic matter content level, and the soil hydrolyzable nitrogen is used as the adjustment factor: when the soil hydrolyzable nitrogen is ≥180 mg / kg, the low supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity; when the soil hydrolyzable nitrogen is ≤100 mg / kg, the high supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity; Method 4: Determine the soil nitrogen supply level of the target plot based on soil texture and surface properties: (2) Based on the soil nitrogen supply level of the target plot determined in step (1), combined with the fertilization method, the nitrogen balance standard of the target plot is determined according to the following table: (3) Obtain Y based on target output grain For corn grain yield, determine the nitrogen absorption of the aboveground part of corn in the target plot according to formula (a-1) or (a-2): N uptake =N grain +N straw (a-1) in: N uptake is the nitrogen uptake by aboveground parts of maize, kg N / ha; N grain is the nitrogen uptake by maize kernels, kg N / ha; N straw is the nitrogen absorption of corn straw, kg N / ha; N uptake =And grain *X grain +Y straw *X straw (a-2) in: N uptake is the nitrogen uptake by aboveground parts of maize, kg N / ha; Y grain is maize grain yield, kg / ha; Y straw is the corn stover biomass, kg / ha; X grain is the nitrogen content of corn kernels, mg / kg; X straw is the nitrogen content of corn straw, mg / kg; (4) Calculate the recommended amount of nitrogen fertilizer for corn in the target plot according to formula (b): N=N uptake +N balance (b); Where N represents the recommended amount of nitrogen fertilizer for corn, kg N / ha; N uptake Indicates the nitrogen absorption of corn aboveground parts, kg N / ha; N balance Expresses nitrogen balance standard, kg N / ha.

2. The method according to claim 1, wherein the corn stalk biomass is calculated according to formula (c): AND straw = And grain * a (c) Y straw is the biomass of corn stover, kg / ha; Y grain is the corn grain yield, kg / ha; a is the conversion coefficient between corn grain yield and corn stalk biomass, where: The conversion factors for different corn varieties are shown in the table below: The nitrogen absorption of corn kernels was calculated according to formula (d): N grain =Y grain * b * 0.001 (d) N grain is the nitrogen absorption of corn kernels, kg N / ha; Y grain is the corn grain yield, kg / ha; b is the conversion coefficient between corn grain yield and corn grain nitrogen absorption, among which the conversion coefficients of different corn varieties are shown in the following table: The nitrogen absorption of corn straw is calculated according to formula (e): N straw = Y straw * c * 0.001 (e) N straw is the nitrogen absorption of corn straw, kg N / ha; Y straw is the biomass of corn straw, kg / ha; c is the conversion coefficient between the biomass of corn straw and the nitrogen absorption of corn straw. The conversion coefficients of different corn varieties are shown in the following table: 。

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