A simplified method for recommending nitrogen fertilizer application rates for winter wheat based on nitrogen balance standards

Abstract

The present invention discloses a simplified method for recommending nitrogen fertilizer dosages for winter wheat based on a nitrogen balance standard, relating to the field of agricultural resources and environmental technology. This method, based on a nitrogen balance standard, recommends nitrogen fertilizer dosages for wheat. This method only requires understanding wheat yield and soil fertility level to make recommendations. While ensuring crop yield, it minimizes nitrogen surplus in the soil, thereby reducing the environmental loss of reactive nitrogen and promoting high-yield, efficient, and sustainable agricultural development.

Description

Technical Field

[0001] This invention relates to the field of agricultural resource and environmental technology, and in particular to a simplified method for recommending nitrogen fertilizer application rates for winter wheat based on nitrogen balance standards. Background Technology

[0002] Wheat is one of the major food crops, and its cultivation consumes a large amount of nitrogen fertilizer, while the problem of excessive nitrogen fertilizer application also exists. Wheat has a long growing season, and the soil texture, fertility, and climate conditions vary greatly in different planting areas, making scientific nitrogen fertilizer management quite difficult.

[0003] Currently, recommended methods for crop nitrogen fertilizer application are mainly developed based on one or more of the following: soil nutrient testing, fertilizer effect functions, and crop or soil models. However, most smallholder farming operations lack the conditions for soil testing and other scientific fertilization methods. Furthermore, due to the low economic returns of wheat cultivation, farmers invest little in scientific fertilization, and many smallholders still rely on experience for fertilization, resulting in widespread irrational fertilization practices. Developing scientifically sound, simple, and efficient recommended fertilization techniques is an urgent need to promote efficient nitrogen fertilizer application and fertilizer conservation and emission reduction in wheat. Summary of the Invention

[0004] The purpose of this invention is to provide a simplified method for recommending the amount of nitrogen fertilizer for wheat based on nitrogen balance standards, so as to solve the problems existing in the prior art.

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

[0006] This invention provides a method for recommending nitrogen fertilizer application rates for winter wheat based on nitrogen balance standards, comprising the following steps:

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

[0008] This invention provides four methods for determining soil nitrogen supply levels:

[0009] Method 1: Determining nitrogen uptake by wheat aboveground parts under nitrogen-free conditions in the target plot. This invention collects and summarizes field fertilization trial data from major wheat-producing areas in China and establishes a database. The top 25%, middle 25%-75%, and bottom 25% of the wheat aboveground nitrogen uptake dataset under nitrogen-free conditions in the database are used as the criteria for classifying high, medium, and low levels of nitrogen supply in paddy field soil (Table 1).

[0010] Method 2: Determining the yield based on wheat yield in the target plot without nitrogen fertilizer application. Based on the Method 1 database, the top 25%, middle 25%-75%, and bottom 25% of the wheat yield dataset under nitrogen-free conditions were used as the criteria for classifying paddy field soil nitrogen supply as high, medium, and low (Table 2).

[0011] Method 3: If soil test results are available for the target plot, classify it according to soil organic matter content (Table 3); specifically:

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

[0013] Method 4: Determine based on the apparent characteristics of the soil texture and color of the target plot (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 for the target plot. Based on the aforementioned database, this invention establishes the relationship between nitrogen application yield response (i.e., the increase in wheat yield in the nitrogen-fertilized treatment compared to the non-nitrogen-fertilized treatment) and soil apparent nitrogen balance (i.e., the difference between the amount of nitrogen applied and the amount absorbed and removed by wheat). While ensuring wheat yield and minimizing nitrogen surplus in the soil, a maximum economic benefit algorithm is used to propose nitrogen balance standards for high, medium, and low soil nitrogen supply levels in wheat fields. Simultaneously, this invention compares the differences in soil apparent nitrogen balance under various fertilization modes, including conventional nitrogen fertilizer application, controlled-release nitrogen fertilizer, deep mechanical application of nitrogen fertilizer, combined application of organic fertilizer, and straw return to the field, and then proposes reference standards for wheat field nitrogen balance under different fertilization modes (Table 5). Based on the soil nitrogen supply level identified in Step 1 and the actual nitrogen fertilizer application mode, refer to Table 5 to determine the nitrogen balance standard for the target plot.

[0024] Table 5

[0025]

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

[0027] The nitrogen uptake of wheat aboveground plants, considering both grain nitrogen uptake and straw nitrogen uptake, can be calculated using formula (1):

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

[0029] Where, N uptake N grain N straw These represent the nitrogen uptake by the aboveground parts of wheat, the nitrogen uptake by wheat grains, and the nitrogen uptake by wheat straw in the target plot (kg N / ha), respectively; Y grain and Y straw X represents wheat grain yield and wheat straw biomass (kg / ha), respectively; grain and X straw These represent the nitrogen content of wheat grains and the nitrogen content of wheat straw (mg / kg), respectively.

[0030] Specifically, Y grain The yield was determined based on the average wheat yield of the target plot over the past 3-5 years when there were no biological stresses.

[0031] Y straw If no measured data is available, it can be obtained using formula (2):

[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 values ​​are shown in Table 6.

[0034] X grain If there is no measured data, then N grain Obtained through formula (3):

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

[0036] Where b represents the conversion coefficient between wheat grain yield and wheat grain nitrogen uptake, and the reference values ​​are shown in Table 6.

[0037] X straw If there is no measured data, then N straw Obtained through formula (4):

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

[0039] Where c represents the conversion coefficient between wheat straw biomass and wheat straw nitrogen uptake, and the reference values ​​are shown in Table 6.

[0040] Table 6

[0041] Conversion factor Winter wheat - Northern growing areas Winter wheat - Southern growing areas a 1.20 1.18 b 19.8 18.9 c 5.6 5.5

[0042] Step 4) Calculate the nitrogen fertilizer application rate for wheat in the target plot: Based on the aboveground nitrogen uptake of wheat in the target plot and the nitrogen balance standard of wheat field, predict the recommended nitrogen fertilizer application rate, which is obtained through formula (5):

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

[0044] Wherein, N represents the recommended nitrogen fertilizer application rate (kg N / ha) for the target plot; N uptake The aboveground nitrogen uptake (kg N / ha) of wheat in the target plot is obtained from step 3); N balance The nitrogen balance standard (kg N / ha) of the target plot is obtained from steps 1) and 2).

[0045] This invention presents a simplified method for recommending nitrogen fertilizer application based on nitrogen balance standards. It can be used with or without soil testing results. Ordinary farmers with some scientific knowledge only need to understand the wheat yield level of the target plot, identify the soil fertility level, and then perform a simple calculation to achieve a scientifically reasonable nitrogen fertilizer recommendation. Compared with existing technologies, it is more suitable for small farmers who lack soil testing and formula fertilization techniques or other fertilization techniques requiring specialized testing equipment and personnel.

[0046] This invention not only provides standard nitrogen balance parameters for conventional nitrogen fertilizer products and application methods, but also provides parameter calibration for high-efficiency fertilization scenarios such as controlled-release fertilizers, deep mechanical application of nitrogen fertilizers, combined application of organic fertilizers, and straw return to the field. Therefore, compared with existing technologies, this invention is more applicable to the diverse nitrogen fertilizer application scenarios for wheat.

[0047] This invention generates relevant nitrogen fertilizer recommendation parameters based on big data from field trials, rather than on the results of individual or a few trials, thus possessing broad representativeness. This invention uses wheat yield response as a response indicator to changes in nitrogen balance, rather than directly using wheat yield. This is because yield response is the increase in yield of the nitrogen-applied treatment relative to the non-nitrogen-applied treatment, and the yield of the non-nitrogen-applied treatment represents the soil fertility level of the plot. Therefore, this invention minimizes the bias in recommended fertilization parameters caused by differences in soil fertility levels at different test sites. Consequently, the nitrogen balance standard provided by this invention is suitable for different wheat types, varieties, and soil and climate conditions.

[0048] Using extensive field validation data from different wheat-growing regions, recommended fertilization practices were conducted. The results showed that the nitrogen fertilizer application rate generated by the method recommended in this invention was well matched with the basic nitrogen supply of soils with different fertility levels and the nitrogen requirements of wheat plants, achieving the goal of simple, efficient, and scientific fertilization.

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

[0050] This invention proposes a method for recommending nitrogen fertilizer application rates for wheat based on nitrogen balance standards. This method only requires knowledge of wheat yield and soil fertility level to recommend nitrogen fertilizer application rates. It can minimize nitrogen surplus in the soil while ensuring crop yield, thereby reducing environmental loss of reactive nitrogen and promoting high-yield, high-efficiency, and sustainable agricultural development. Detailed Implementation

[0051] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0052] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0053] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0054] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

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

[0056] Example 1

[0057] To verify the feasibility of applying the nitrogen fertilizer application recommendation method based on the nitrogen balance standard to wheat, this invention utilizes extensive field trial data from major wheat-producing areas in China to conduct recommended fertilization practices and compares the results with those of local farmers' habitual fertilization and other widely accepted scientific fertilization methods to verify the rationality of the recommendations.

[0058] Field trials were conducted from 2017 to 2020 in major wheat-producing provinces such as Henan, Shandong, Hebei, Shanxi, and Inner Mongolia. The recommended nitrogen fertilizer application method based on nitrogen balance standards was validated in a total of 44 experimental plots. The number of trials and regions validating different fertilization methods are shown in Table 7. Based on the nitrogen uptake of wheat aboveground parts in the no-nitrogen-fertilizer treatment of each experimental plot, the soil nitrogen supply level of that plot was determined using the standards provided in Table 1 (Table 7). Based on the fertilization method and soil nitrogen supply level of each experimental plot, the nitrogen balance standard of that plot was determined using the standards provided in Table 5 (Table 8). The measured value of the highest aboveground nitrogen uptake of wheat among all treatments was used as the target nitrogen uptake. The recommended nitrogen fertilizer application rate (OPT) for that plot was predicted using formula (5), and compared with the local farmer's habitual nitrogen fertilizer application rate (FP), the local soil testing and formula fertilization recommended nitrogen fertilizer application rate (ST), and the nutrient expert method recommended nitrogen fertilizer application rate (NE) based on the same plot (Table 8).

[0059] Table 7

[0060]

[0061] Table 8

[0062]

[0063] Table 8 summarizes the average nitrogen fertilizer application results for four fertilization methods on relevant plots with different soil fertility levels. The results show that in all experimental plots, the average nitrogen requirement for wheat was 171 kg N / ha, and the average application of OPT nitrogen fertilizer was 199 kg N / ha. This application rate falls between the recommended values ​​of the two scientific fertilization methods, ST and NE, thus ensuring the rationality of the recommendations. Compared to farmers' conventional fertilization practices, FP (nitrogen fertilizer) was reduced by 22.6%. In high-fertility plots, OPT nitrogen fertilizer application showed the greatest potential for reduction compared to FP, at 30.5%. Under low, medium, and high soil fertility levels, the average application of OPT nitrogen fertilizer was 191, 221, and 185 kg N / ha, respectively. The difference from the ST recommendation ranged from -3 to -41 kg N / ha, and the difference from the NE recommendation ranged from 7 to 24 kg N / ha.

[0064] In summary, the nitrogen fertilizer application recommendation method based on nitrogen balance standards proposed in this invention can significantly reduce the nitrogen fertilizer application habits of current farmers, achieving the goal of reducing nitrogen fertilizer use while increasing efficiency. The recommended results deviate slightly from the two scientific fertilization methods, ST and NE, mainly due to differences in their recommendation principles, but they generally fall within the upper and lower ranges of the recommended values ​​of the two methods, indicating that the recommended range is basically reasonable. Therefore, the field verification test results show that the nitrogen fertilizer application recommendation method based on nitrogen balance standards proposed in this invention can be used for nitrogen fertilizer application decisions in wheat.

[0065] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A simplified method for recommending nitrogen fertilizer application rates for winter wheat based on nitrogen balance standards, characterized in that, Includes the following steps: (1) Determine the soil nitrogen supply level of the target plot using any one of methods 1-4: Method 1: Determine the soil nitrogen supply level of the target plot based on the nitrogen uptake of the aboveground parts of wheat without nitrogen fertilizer, according to different wheat planting areas: Method 2: Determine the soil nitrogen supply level of the target plot based on the wheat yield without nitrogen fertilizer, according to different wheat-growing areas. Method 3: Classify the soil nitrogen supply level of the target plot based on soil organic matter content: Soil nitrogen supply level is based on soil organic matter content as the basis for nitrogen supply level assessment, and soil hydrolyzable nitrogen is used as the adjustment factor: when soil hydrolyzable nitrogen is ≥180mg / kg, the low supply capacity of soil nitrogen supply level is adjusted to medium supply capacity; when soil hydrolyzable nitrogen is ≤100mg / kg, the high supply capacity of soil nitrogen supply level is adjusted to medium supply capacity. Method 4: Determine the soil nitrogen supply level of the target plot based on soil texture and apparent properties: (2) Based on the soil nitrogen supply level of the target plot determined in step (1), and in conjunction with the fertilization method, determine the nitrogen balance standard of the target plot according to the following table: (3) Obtain Y based on target output grain This refers to wheat grain yield. The nitrogen uptake of the aboveground wheat plants 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 Nitrogen uptake by wheat aboveground parts, kg N / ha; N grain Nitrogen uptake by wheat grains, kg N / ha; N straw Nitrogen uptake by wheat straw, kg N / ha; N uptake =Y grain *X grain +And straw *X straw (a-2) in: N uptake Nitrogen uptake by wheat aboveground parts, kg N / ha; Y grain Wheat grain yield, kg / ha; Y straw Wheat straw biomass, kg / ha; X grain Nitrogen content of wheat grains, mg / kg; X straw Nitrogen content of wheat straw, mg / kg; (4) Calculate the recommended amount of nitrogen fertilizer for wheat in the target plot according to formula (b): N=N uptake +N balance (b); Where N represents the recommended application rate of nitrogen fertilizer for wheat, kg N / ha; N uptake This indicates the amount of nitrogen absorbed by the aboveground parts of wheat, expressed in kg N / ha; N balance Nitrogen balance standard, kg N / ha; If no actual measurement value is available for the wheat straw biomass, it can be calculated according to formula (c): AND straw =Y grain *a (c) Y straw Wheat straw biomass, kg / ha; Y grain denoted as wheat grain yield, kg / ha; a represents the conversion coefficient between wheat grain yield and wheat straw biomass, with the conversion coefficients for different wheat varieties shown in the table below; If no actual measurement data is available for nitrogen uptake in wheat grains, it can be calculated using formula (d): N grain =Y grain *b*0.001 (d) N grain Nitrogen uptake by wheat grains, kg N / ha; Y grain denoted as wheat grain yield, kg / ha; b represents the conversion coefficient between wheat grain yield and wheat grain nitrogen uptake. The conversion coefficients for different wheat varieties are shown in the table below. If no actual measurement data is available for the nitrogen uptake of wheat straw, it can be calculated using equation (e): N straw = Y straw * c * 0.001 (e) N straw Nitrogen uptake by wheat straw, kg N / ha; Y straw denoted as wheat straw biomass, kg / ha; c represents the conversion coefficient between wheat straw biomass and wheat straw nitrogen uptake. The conversion coefficients for different wheat varieties are shown in the table below:

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