Simplified winter wheat nitrogen fertilizer dosage recommendation method based on nitrogen balance standard

Abstract

The invention discloses a simplified winter wheat nitrogen fertilizer dosage recommendation method based on a nitrogen balance standard, and relates to the technical field of agricultural resource environment. According to the wheat nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard, the nitrogen fertilizer dosage can be recommended only by knowing the wheat 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 winter wheat based on a nitrogen balance standard. Background Art

[0002] Wheat is one of the main food crops. The planting process consumes a lot of nitrogen fertilizer, and there is also the problem of excessive nitrogen fertilizer application. Wheat has a long growing period, and the soil texture, fertility, and climatic conditions vary greatly in different planting areas, making scientific nitrogen fertilizer management difficult.

[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 do not have the conditions for soil testing and fertilization or other scientific fertilization. At the same time, due to the low economic benefits of growing wheat, farmers invest less in scientific fertilization. A large number of small farmers still fertilize according to experience, and unreasonable fertilization is common. Developing a scientific, reasonable, simple and efficient recommended fertilization technology is an urgent need to promote the efficient application of wheat nitrogen fertilizer and fertilizer saving and emission reduction. Summary of the invention

[0004] The purpose of the present invention is to provide a lightly simplified method for recommending nitrogen fertilizer dosage for wheat 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 winter wheat based on nitrogen balance standard, comprising the following steps:

[0007] Step 1): Identify the soil fertility level of the wheat field: 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 wheat without nitrogen fertilizer application in the target plot. The present invention collects and summarizes the fertilization field test data conducted in the main wheat producing areas in China and establishes a database. The first 25%, middle 25%-75%, and last 25% of the nitrogen absorption data set of the aboveground part of wheat without nitrogen fertilizer application in the database are used as the classification criteria for high, medium, and low levels of nitrogen supply in paddy field soil (Table 1);

[0010] Method 2: Determine based on the wheat yield of the target plot without nitrogen fertilizer application. Based on the database of Method 1, the first 25%, middle 25%-75%, and last 25% of the wheat yield data set without nitrogen fertilizer application were used as the classification criteria for high, medium, and low levels of nitrogen supply in paddy field soil (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 wheat yield increment of the target plot treated with nitrogen fertilizer compared to that treated without nitrogen fertilizer) and the apparent nitrogen balance of the soil (i.e., the difference between the amount of nitrogen applied and the amount absorbed and removed by wheat). On the basis of ensuring wheat yield and minimizing nitrogen surplus in the soil, the maximum economic benefit algorithm is used to propose nitrogen balance standards for wheat fields 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 of wheat fields under different fertilization modes (Table 5). According to the soil nitrogen supply level and field nitrogen fertilizer application mode identified in step 1, refer to Table 5 to determine the nitrogen balance standard of the target plot.

[0024] Table 5

[0025]

[0026] Step 3) Determine the nitrogen uptake of wheat plants in the target plot:

[0027] The nitrogen absorption of wheat aboveground plants takes into account the nitrogen absorption of grains and the nitrogen absorption of straw, which can be calculated by formula (1):

[0028] N uptake = N grain + N straw = Y grain * X grain + Y straw * X straw (1)

[0029] Among them, N uptake 、N grain 、N straw represents the nitrogen absorption of the aboveground part of wheat, the nitrogen absorption of wheat grains and the nitrogen absorption of wheat straw in the target plot (kg N / ha); Y grain and Y straw represent wheat grain yield and wheat straw biomass (kg / ha), respectively; X grain and X straw They represent the nitrogen content of wheat grain and wheat straw (mg / kg), respectively.

[0030] Specifically, Y grain Determined based on the average wheat yield of the target plot in the past 3-5 years without biological stress.

[0031] Y straw If there is no measured data, the following formula (2) can be used to obtain:

[0032] Y straw =Y grain * a (2)

[0033] Where a represents the conversion coefficient between wheat grain yield and wheat straw biomass, and the reference value is shown in Table 6.

[0034] X grain If there is no measured data, then N grain By formula (3), we can obtain:

[0035] N grain = Y grain * b * 0.001 (3)

[0036] Wherein, b represents the conversion coefficient between wheat grain yield and wheat grain nitrogen absorption. The reference value is shown in Table 6.

[0037] X straw If there is no measured data, then N straw By formula (4), we can obtain:

[0038] N straw = Y straw * c * 0.001 (4)

[0039] Wherein, c represents the conversion coefficient between wheat straw biomass and wheat straw nitrogen absorption, and the reference value is shown in Table 6.

[0040] Table 6

[0041] Conversion Factor Winter wheat-Northern planting area Winter wheat-Southern planting area a 1.20 1.18 b 19.8 18.9 c 5.6 5.5

[0042] Step 4) Calculate the nitrogen fertilizer dosage for wheat in the target plot: predict the recommended nitrogen fertilizer dosage based on the nitrogen absorption of the aboveground part of wheat in the target plot and the nitrogen balance standard of the wheat field, which can be obtained by formula (5):

[0043] N=N uptake +N balance (5)

[0044] Wherein, N represents the recommended amount of nitrogen fertilizer for the target plot (kg N / ha); uptake represents the aboveground nitrogen absorption of wheat 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).

[0045] The nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard of the present invention is a simplified recommendation method that can be used with or without soil test results. Ordinary farmers with a certain amount of scientific knowledge only need to understand the wheat 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 small farmers who do not have soil testing and formula fertilization or other fertilization technical conditions that require professional testing equipment and personnel.

[0046] The present invention not only provides standard parameters for nitrogen balance for conventional nitrogen fertilizer products and application methods, but also performs parameter correction for efficient fertilization scenarios such as slow-release fertilizers, deep mechanical nitrogen fertilizer application, organic fertilizer application, and straw return to the field. Therefore, compared with the prior art, the present invention is more suitable for the current diversified wheat nitrogen fertilizer application scenarios.

[0047] 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 is widely representative. The present invention uses wheat yield response as a response indicator of nitrogen balance changes, rather than directly using wheat yield, because the yield response is the increment of the yield of nitrogen treatment relative to the yield of no nitrogen treatment, and the yield of no nitrogen treatment represents the soil fertility level of the plot, thus eliminating the deviation of recommended fertilization parameters caused by differences in soil fertility levels at different test points to the greatest extent. Therefore, the nitrogen balance standard provided by the present invention is suitable for different wheat types, varieties and soil climate and environmental conditions.

[0048] A large amount of field verification test data from different wheat regions was used to carry out recommended fertilization practices. The results showed that the amount of nitrogen fertilizer produced by the recommended method of the present invention better matched the basic nitrogen supply of soils with different fertility and the nitrogen demand of wheat plants, achieving the goal of simple, efficient and scientific fertilization.

[0049] The present invention discloses the following technical effects:

[0050] The present invention proposes a method for recommending nitrogen fertilizer dosage for wheat based on the nitrogen balance standard. This method only requires understanding of wheat yield and soil fertility level to recommend nitrogen fertilizer dosage. It can minimize nitrogen surplus in the soil on the basis of ensuring crop yield, thereby reducing the environmental loss of active nitrogen, thereby promoting high-yield, efficient, sustainable and healthy development of agriculture. DETAILED DESCRIPTION

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0056] Example 1

[0057] In order to verify the feasibility of applying the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard to wheat, the present invention uses a large amount of field test data from China's main wheat producing areas 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.

[0058] The field experiment was conducted in the main wheat producing provinces of Henan, Shandong, Hebei, Shanxi, and Inner Mongolia from 2017 to 2020. A total of 44 test plots were used to verify the recommended method of nitrogen fertilizer application based on the nitrogen balance standard. The number and regions of the experiments verifying different fertilization methods are shown in Table 7. According to the nitrogen absorption of the aboveground part of wheat in each test plot without nitrogen fertilizer application, the standard provided in Table 1 was used to determine the nitrogen supply level of the soil in the plot (Table 7). According to the fertilization method and soil nitrogen supply level of each test plot, the nitrogen balance standard of the plot was determined using the standard provided in Table 5 (Table 8). The highest measured value of aboveground nitrogen absorption of wheat in all treatments was used as the target nitrogen absorption, and the recommended nitrogen fertilizer application rate (OPT) of the plot was predicted by formula (5), and compared with the local farmers' habitual nitrogen fertilizer application rate (FP), the local soil test formula fertilization recommended nitrogen fertilizer application rate (ST), and the nitrogen fertilizer application rate recommended by the nutrient expert method (NE) in the same plot (Table 8).

[0059] Table 7

[0060]

[0061] Table 8

[0062]

[0063] Table 8 summarizes the average nitrogen fertilizer application results of the four fertilization methods on the relevant plots with different soil fertility levels. The results show that in all test plots, the average nitrogen demand of wheat is 171kg N / ha, and the average nitrogen application of OPT is 199kg N / ha, which is between the recommended values ​​of the two scientific fertilization methods ST and NE, basically ensuring the rationality of their recommendations. Compared with farmers' habitual fertilization, FP is reduced by 22.6%, among which OPT nitrogen fertilizer application has the greatest potential for reduction compared with FP in high fertility plots, which is 30.5%. The average nitrogen application of OPT in low, medium and high soil fertility is 191, 221 and 185kg N / ha, respectively, with a difference of -3 to -41kg N / ha from the ST recommended method and a difference of 7 to 24kg N / ha from the NE recommended method.

[0064] In general, the application of the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard of 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 range is basically reasonable. Therefore, the field verification test results show that the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard proposed by the present invention can be used for nitrogen fertilizer dosage decision-making for wheat.

[0065] 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 nitrogen fertilizer dosage for winter wheat based on 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 wheat planting areas, the soil nitrogen supply level of the target plot is determined based on the nitrogen absorption of the aboveground part of wheat without nitrogen fertilizer: Method 2: According to different wheat planting areas, determine the soil nitrogen supply level of the target plot based on the wheat 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 , which is the wheat grain yield, and the nitrogen absorption of the aboveground part of wheat in the target plot is determined according to formula (a-1) or (a-2): N uptake =N grain +N straw (a-1) in: N uptake is the nitrogen uptake by the aboveground part of wheat, kg N / ha; N grain is the nitrogen uptake by wheat grain, kg N / ha; N straw is the nitrogen absorption of wheat straw, kg N / ha; N uptake =And grain *X grain +Y straw *X straw (a-2) in: N uptake is the nitrogen uptake by the aboveground part of wheat, kg N / ha; Y grain is wheat grain yield, kg / ha; Y straw is the biomass of wheat straw, kg / ha; X grain is the nitrogen content of wheat grain, mg / kg; X straw is the nitrogen content of wheat straw, mg / kg; (4) Calculate the recommended nitrogen fertilizer dosage for wheat in the target plot according to formula (b): N=N uptake +N balance (b); Where N represents the recommended amount of nitrogen fertilizer for wheat, kg N / ha; N uptake Indicates nitrogen absorption of wheat aboveground parts, kg N / ha; N balance Expresses nitrogen balance standard, kg N / ha.

2. The method according to claim 1, wherein if there is no measured value for the wheat straw biomass, the biomass can be calculated according to formula (c): AND straw = And grain * a (c) Y straw is the biomass of wheat straw, kg / ha; Y grain is the wheat grain yield, kg / ha; a is the conversion coefficient between wheat grain yield and wheat straw biomass, where: The conversion factors for different wheat varieties are shown in the table below; If there is no measured value for nitrogen absorption of wheat grains, it can be calculated according to formula (d): N grain =Y grain * b * 0.001 (d) N grain is the nitrogen absorption of wheat grain, kg N / ha; Y grain is the wheat grain yield, kg / ha; b is the conversion coefficient between wheat grain yield and wheat grain nitrogen absorption, where the conversion coefficients of different wheat varieties are shown in the table below; If there is no measured value for nitrogen absorption by wheat straw, it can be calculated according to formula (e): N straw = Y straw * c * 0.001 (e) N straw is the nitrogen absorption of wheat straw, kg N / ha; Y straw is the biomass of wheat straw, kg / ha; c is the conversion coefficient between the biomass of wheat straw and the nitrogen absorption of wheat straw. The conversion coefficients of different wheat varieties are shown in the following table: 。

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